1
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Li C, Song Y, Wang X, Lei M, Chen X, Xu H, Peng R, Feng D. Interface-Suppressed Nematicity and Enhanced Superconducting Pairing Strength of FeSe/NdFeO 3 in the Low-Doping Regime. NANO LETTERS 2024; 24:8303-8310. [PMID: 38934420 DOI: 10.1021/acs.nanolett.4c01493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/28/2024]
Abstract
The discovery of interfacial superconductivity in monolayer FeSe/oxides has spurred intensive research interest. Here we not only extend the FeSe/FeOx superconducting interface to FeSe/NdFeO3 but also establish robust interface-enhanced superconductivity at a very low doping level. Specifically, well-annealed FeSe/NdFeO3 exhibits a low doping level of 0.038-0.046 e-/Fe with a larger superconducting pairing gap without a nematic gap, indicating an enhancement of the enhanced superconducting pairing strength and suppression of nematicity by the FeSe/FeOx interface compared with those of thick FeSe films. These results improve our understanding of the roles of the oxide interface in the low-electron-doped regime.
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Affiliation(s)
- Chihao Li
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
| | - Yuanhe Song
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
| | - Xiaoxiao Wang
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
| | - Minyinan Lei
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
| | - Xiaoyang Chen
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
| | - Haichao Xu
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Rui Peng
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Donglai Feng
- Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200438, China
- National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China
- New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei 230026, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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2
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Liu R, Zhang W, Wei Y, Tao Z, Asmara TC, Li Y, Strocov VN, Yu R, Si Q, Schmitt T, Lu X. Nematic Spin Correlations Pervading the Phase Diagram of FeSe_{1-x}S_{x}. PHYSICAL REVIEW LETTERS 2024; 132:016501. [PMID: 38242670 DOI: 10.1103/physrevlett.132.016501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Accepted: 12/08/2023] [Indexed: 01/21/2024]
Abstract
We use resonant inelastic x-ray scattering (RIXS) at the Fe-L_{3} edge to study the spin excitations of uniaxial-strained and unstrained FeSe_{1-x}S_{x} (0≤x≤0.21) samples. The measurements on unstrained samples reveal dispersive spin excitations in all doping levels, which show only minor doping dependence in energy dispersion, lifetime, and intensity, indicating that high-energy spin excitations are only marginally affected by sulfur doping. RIXS measurements on uniaxial-strained samples reveal that the high-energy spin-excitation anisotropy observed previously in FeSe is also present in the doping range 0200 K in x=0.18 and reaches a maximum around the nematic quantum critical doping (x_{c}≈0.17). Since the spin-excitation anisotropy directly reflects the existence of nematic spin correlations, our results indicate that high-energy nematic spin correlations pervade the regime of nematicity in the phase diagram and are enhanced by the nematic quantum criticality. These results emphasize the essential role of spin fluctuations in driving electronic nematicity and highlight the capability of uniaxial strain in tuning spin excitations in quantum materials hosting strong magnetoelastic coupling and electronic nematicity.
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Affiliation(s)
- Ruixian Liu
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Wenliang Zhang
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Yuan Wei
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Zhen Tao
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Teguh C Asmara
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- European X-Ray Free-Electron Laser Facility GmbH, 22869 Schenefeld, Germany
| | - Yi Li
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Vladimir N Strocov
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Rong Yu
- Department of Physics, Renmin University of China, Beijing 100872, China
| | - Qimiao Si
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Thorsten Schmitt
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Xingye Lu
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
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3
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Aouelela M, Taha M, El-dek SI, Hassan A, Vasiliev AN, Abdel-Hafiez M. Synthesis and Characterization of Molybdenum- and Sulfur-Doped FeSe. ACS OMEGA 2023; 8:36553-36561. [PMID: 37810706 PMCID: PMC10552506 DOI: 10.1021/acsomega.3c05684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 08/22/2023] [Indexed: 10/10/2023]
Abstract
During the past decade, two-dimensional (2D) layered materials opened novel opportunities for the exploration of exciting new physics and devices owing to their physical and electronic properties. Among 2D materials, iron selenide has attracted much attention from several physicists as they provide a fruitful stage for developing new superconductors. Chemical doping offers a powerful approach to manipulate and optimize the electronic structure and physical properties of materials. Here, to reveal how doping affects the physical properties in FeSe, we report on complementary measurements of molybdenum- and sulfur-doped FeSe with theoretical calculations. Mo0.1Fe0.9Se0.9S0.1 was synthesized by a one-step solid-state reaction method. Crystal structure and morphology were studied using powder X-ray diffraction and scanning electron microscopy. Thermal stability and decomposition behavior in doped samples were studied by thermogravimetric analysis, and to understand the microscopic influence of doping, we performed Raman spectroscopy. First-principles calculations of the electronic structure illustrate distinct changes of electronic structures of the substituted FeSe systems, which can be responsible for their superconducting properties.
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Affiliation(s)
- Marwa
H.A. Aouelela
- Materials
Science and Nanotechnology Department, Faculty of Postgraduate Studies
for Advanced Sciences, Beni-Suef University, 62511 Beni-Suef, Egypt
| | - Mohamed Taha
- Materials
Science and Nanotechnology Department, Faculty of Postgraduate Studies
for Advanced Sciences, Beni-Suef University, 62511 Beni-Suef, Egypt
| | - Samaa I. El-dek
- Materials
Science and Nanotechnology Department, Faculty of Postgraduate Studies
for Advanced Sciences, Beni-Suef University, 62511 Beni-Suef, Egypt
| | - Abdelwahab Hassan
- Department
of Physics, Faculty of Science, Fayoum University, 63514 Fayoum, Egypt
| | - Alexander N. Vasiliev
- National
University of Science and Technology MISiS, 119049 Moscow, Russia
- Lomonosov
Moscow State University, 119991 Moscow, Russia
| | - Mahmoud Abdel-Hafiez
- Department
of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala, Sweden
- Department
of Applied Physics and Astronomy, University
of Sharjah, P. O. Box 27272 Sharjah, United Arab Emirates
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4
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Occhialini CA, Sanchez JJ, Song Q, Fabbris G, Choi Y, Kim JW, Ryan PJ, Comin R. Spontaneous orbital polarization in the nematic phase of FeSe. NATURE MATERIALS 2023; 22:985-991. [PMID: 37349393 DOI: 10.1038/s41563-023-01585-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 05/19/2023] [Indexed: 06/24/2023]
Abstract
The origin of nematicity in FeSe remains a critical outstanding question towards understanding unconventional superconductivity in proximity to nematic order. To understand what drives the nematicity, it is essential to determine which electronic degree of freedom admits a spontaneous order parameter independent from the structural distortion. Here we use X-ray linear dichroism at the Fe K pre-edge to measure the anisotropy of the 3d orbital occupation as a function of in situ applied stress and temperature across the nematic transition. Along with using X-ray diffraction to precisely quantify the strain state, we reveal a lattice-independent, spontaneously ordered orbital polarization within the nematic phase, as well as an orbital polarizability that diverges as the transition is approached from above. These results provide strong evidence that spontaneous orbital polarization serves as the primary order parameter of the nematic phase.
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Affiliation(s)
- Connor A Occhialini
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Joshua J Sanchez
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Qian Song
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Gilberto Fabbris
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA
| | - Yongseong Choi
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA
| | - Jong-Woo Kim
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA
| | - Philip J Ryan
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, USA
| | - Riccardo Comin
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
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5
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Čulo M, Licciardello S, Ishida K, Mukasa K, Ayres J, Buhot J, Hsu YT, Imajo S, Qiu MW, Saito M, Uezono Y, Otsuka T, Watanabe T, Kindo K, Shibauchi T, Kasahara S, Matsuda Y, Hussey NE. Expanded quantum vortex liquid regimes in the electron nematic superconductors FeSe 1-xS x and FeSe 1-xTe x. Nat Commun 2023; 14:4150. [PMID: 37438333 DOI: 10.1038/s41467-023-39730-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/21/2023] [Indexed: 07/14/2023] Open
Abstract
The quantum vortex liquid (QVL) is an intriguing state of type-II superconductors in which intense quantum fluctuations of the superconducting (SC) order parameter destroy the Abrikosov lattice even at very low temperatures. Such a state has only rarely been observed, however, and remains poorly understood. One of the key questions is the precise origin of such intense quantum fluctuations and the role of nearby non-SC phases or quantum critical points in amplifying these effects. Here we report a high-field magnetotransport study of FeSe1-xSx and FeSe1-xTex which show a broad QVL regime both within and beyond their respective electron nematic phases. A clear correlation is found between the extent of the QVL and the strength of the superconductivity. This comparative study enables us to identify the essential elements that promote the QVL regime in unconventional superconductors and to demonstrate that the QVL regime itself is most extended wherever superconductivity is weakest.
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Affiliation(s)
- M Čulo
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands.
- Institut za fiziku, Bijenička cesta 46, HR-10000, Zagreb, Croatia.
| | - S Licciardello
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands
| | - K Ishida
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - K Mukasa
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - J Ayres
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK
| | - J Buhot
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK
| | - Y-T Hsu
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands
- Center for Theory and Computation, National Tsing Hua University, No. 101, Section. 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan
| | - S Imajo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - M W Qiu
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - M Saito
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - Y Uezono
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, 036-8561, Japan
| | - T Otsuka
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, 036-8561, Japan
| | - T Watanabe
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori, 036-8561, Japan
| | - K Kindo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - T Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan
| | - S Kasahara
- Research Institute for Interdisciplinary Science, Okayama University, 3-1-1 Tsushimanaka, Kita-Ku, Okayama, 700-8530, Japan
| | - Y Matsuda
- Department of Physics, Kyoto University, Sakyo-Ku, Kyoto, 606-8502, Japan
| | - N E Hussey
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, Netherlands.
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK.
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6
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Chen Z, Li D, Lu Z, Liu Y, Zhang J, Li Y, Yin R, Li M, Zhang T, Dong X, Yan YJ, Feng DL. Charge order driven by multiple-Q spin fluctuations in heavily electron-doped iron selenide superconductors. Nat Commun 2023; 14:2023. [PMID: 37041177 PMCID: PMC10090174 DOI: 10.1038/s41467-023-37792-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 03/28/2023] [Indexed: 04/13/2023] Open
Abstract
Intertwined spin and charge orders have been widely studied in high-temperature superconductors, since their fluctuations may facilitate electron pairing; however, they are rarely identified in heavily electron-doped iron selenides. Here, using scanning tunneling microscopy, we show that when the superconductivity of (Li0.84Fe0.16OH)Fe1-xSe is suppressed by introducing Fe-site defects, a short-ranged checkerboard charge order emerges, propagating along the Fe-Fe directions with an approximately 2aFe period. It persists throughout the whole phase space tuned by Fe-site defect density, from a defect-pinned local pattern in optimally doped samples to an extended order in samples with lower Tc or non-superconducting. Intriguingly, our simulations indicate that the charge order is likely driven by multiple-Q spin density waves originating from the spin fluctuations observed by inelastic neutron scattering. Our study proves the presence of a competing order in heavily electron-doped iron selenides, and demonstrates the potential of charge order as a tool to detect spin fluctuations.
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Affiliation(s)
- Ziyuan Chen
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Dong Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zouyouwei Lu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yue Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jiakang Zhang
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Yuanji Li
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Ruotong Yin
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Mingzhe Li
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Tong Zhang
- Department of Physics, State Key Laboratory of Surface Physics and Advanced Material Laboratory, Fudan University, Shanghai, 200438, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, 210093, China
- Shanghai Research Center for Quantum Sciences, Shanghai, 201315, China
| | - Xiaoli Dong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Ya-Jun Yan
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China.
| | - Dong-Lai Feng
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, 230026, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, 210093, China.
- Shanghai Research Center for Quantum Sciences, Shanghai, 201315, China.
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7
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Hall Effect Anisotropy in the Paramagnetic Phase of Ho 0.8Lu 0.2B 12 Induced by Dynamic Charge Stripes. Molecules 2023; 28:molecules28020676. [PMID: 36677734 PMCID: PMC9863903 DOI: 10.3390/molecules28020676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/22/2022] [Accepted: 12/31/2022] [Indexed: 01/11/2023] Open
Abstract
A detailed study of charge transport in the paramagnetic phase of the cage-cluster dodecaboride Ho0.8Lu0.2B12 with an instability both of the fcc lattice (cooperative Jahn−Teller effect) and the electronic structure (dynamic charge stripes) was carried out at temperatures 1.9−300 K in magnetic fields up to 80 kOe. Four mono-domain single crystals of Ho0.8Lu0.2B12 samples with different crystal axis orientation were investigated in order to establish the singularities of Hall effect, which develop due to (i) the electronic phase separation (stripes) and (ii) formation of the disordered cage-glass state below T*~60 K. It was demonstrated that a considerable intrinsic anisotropic positive component ρanxy appears at low temperatures in addition to the ordinary negative Hall resistivity contribution in magnetic fields above 40 kOe applied along the [001] and [110] axes. A relation between anomalous components of the resistivity tensor ρanxy~ρanxx1.7 was found for H||[001] below T*~60 K, and a power law ρanxy~ρanxx0.83 for the orientation H||[110] at temperatures T < TS~15 K. It is argued that below characteristic temperature TS~15 K the anomalous odd ρanxy(T) and even ρanxx(T) parts of the resistivity tensor may be interpreted in terms of formation of long chains in the filamentary structure of fluctuating charges (stripes). We assume that these ρanxy(H||[001]) and ρanxy(H||[110]) components represent the intrinsic (Berry phase contribution) and extrinsic (skew scattering) mechanism, respectively. Apart from them, an additional ferromagnetic contribution to both isotropic and anisotropic components in the Hall signal was registered and attributed to the effect of magnetic polarization of 5d states (ferromagnetic nano-domains) in the conduction band of Ho0.8Lu0.2B12.
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8
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Unconventional localization of electrons inside of a nematic electronic phase. Proc Natl Acad Sci U S A 2022; 119:e2200405119. [PMID: 36256805 PMCID: PMC9618067 DOI: 10.1073/pnas.2200405119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Among iron-based superconductors, FeSe displays an anomalous electronic nematic state, strong electronic correlations, and orbitally dependent band shifts that can influence its superconducting pairing. Here, we report detailed magnetotransport studies of thin flakes of FeSe that reveal unconventional transport, in which the hole carriers remain highly mobile, whereas the mobility of the electron carriers is low, and weakly temperature dependent, inside the nematic phase. This suggests an unusual localization of negative charge carriers that may be caused by orbital-dependent enhanced correlations, scattering of spin fluctuations, and/or a topological electronic transition. As the superconductivity is suppressed by reducing the flake thickness, it suggests that the electron pockets participate actively in pairing. By doping, electron pockets expand, enabling high-Tc superconductivity. The magnetotransport behavior inside the nematic phase of bulk FeSe reveals unusual multiband effects that cannot be reconciled with a simple two-band approximation proposed by surface-sensitive spectroscopic probes. In order to understand the role played by the multiband electronic structure and the degree of two-dimensionality, we have investigated the electronic properties of exfoliated flakes of FeSe by reducing their thickness. Based on magnetotransport and Hall resistivity measurements, we assess the mobility spectrum that suggests an unusual asymmetry between the mobilities of the electrons and holes, with the electron carriers becoming localized inside the nematic phase. Quantum oscillations in magnetic fields up to 38 T indicate the presence of a hole-like quasiparticle with a lighter effective mass and a quantum scattering time three times shorter, as compared with bulk FeSe. The observed localization of negative charge carriers by reducing dimensionality can be driven by orbitally dependent correlation effects, enhanced interband spin fluctuations, or a Lifshitz-like transition, which affect mainly the electron bands. The electronic localization leads to a fragile two-dimensional superconductivity in thin flakes of FeSe, in contrast to the two-dimensional high-Tc induced with electron doping via dosing or using a suitable interface.
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Xie T, Liu C, Kajimoto R, Ikeuchi K, Li S, Luo H. Spin fluctuations in the 112-type iron-based superconductor Ca 0.82La 0.18Fe 0.96Ni 0.04As 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:474001. [PMID: 36137515 DOI: 10.1088/1361-648x/ac9441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 09/22/2022] [Indexed: 06/16/2023]
Abstract
We report time-of-flight inelastic neutron scattering (INS) investigations on the spin fluctuation spectrum in the 112-type iron-based superconductor (FeSC) Ca0.82La0.18Fe0.96Ni0.04As2(CaLa-112). In comparison to the 122-type FeSCs with a centrosymmetric tetragonal lattice structure (space groupI4/mmm) at room temperature and an in-plane stripe-type antiferromagnetic (AF) order at low temperature, the 112 system has a noncentrosymmetric structure (space groupP21) with additional zigzag arsenic chains between Ca/La layers and a magnetic ground state with similar wavevectorQAFbut different orientations of ordered moments in the parent compounds. Our INS study clearly reveals that the in-plane dispersions and the bandwidth of spin excitations in the superconducting CaLa-112 closely resemble to those in 122 systems. While the total fluctuating moments⟨m2⟩≈4.6±0.2μB2/Fe are larger than 122 system, the dynamic correlation lengths are similar (ξ ≈ 10 Å). These results suggest that superconductivity in iron arsenides may have a common magnetic origin under similar magnetic exchange couplings with a dual nature from local moments and itinerant electrons, despite their different magnetic patterns and lattice symmetries.
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Affiliation(s)
- Tao Xie
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America
| | - Chang Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Ryoichi Kajimoto
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Kazuhiko Ikeuchi
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, Tokai, Ibaraki 319-1106, Japan
| | - Shiliang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Huiqian Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
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10
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Wang A, Milosavljevic A, Abeykoon AMM, Ivanovski V, Du Q, Baum A, Stavitski E, Liu Y, Lazarevic N, Attenkofer K, Hackl R, Popovic Z, Petrovic C. Suppression of Superconductivity and Nematic Order in Fe 1-ySe 1-xS x (0 ≤ x ≤ 1; y ≤ 0.1) Crystals by Anion Height Disorder. Inorg Chem 2022; 61:11036-11045. [PMID: 35830279 DOI: 10.1021/acs.inorgchem.2c00568] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Connections between crystal chemistry and critical temperature Tc have been in the focus of superconductivity, one of the most widely studied phenomena in physics, chemistry, and materials science alike. In most Fe-based superconductors, materials chemistry and physics conspire so that Tc correlates with the average anion height above the Fe plane, i.e., with the geometry of the FeAs4 or FeCh4 (Ch = Te, Se, or S) tetrahedron. By synthesizing Fe1-ySe1-xSx (0 ≤ x ≤ 1; y ≤ 0.1), we find that in alloyed crystals Tc is not correlated with the anion height like it is for most other Fe superconductors. Instead, changes in Tc(x) and tetragonal-to-orthorhombic (nematic) transition Ts(x) upon cooling are correlated with disorder in Fe vibrations in the direction orthogonal to Fe planes, along the crystallographic c-axis. The disorder stems from the random nature of S substitution, causing deformed Fe(Se,S)4 tetrahedra with different Fe-Se and Fe-S bond distances. Our results provide evidence of Tc and Ts suppression by disorder in anion height. The connection to local crystal chemistry may be exploited in computational prediction of new superconducting materials with FeSe/S building blocks.
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Affiliation(s)
- Aifeng Wang
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Ana Milosavljevic
- Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - A M Milinda Abeykoon
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Valentin Ivanovski
- Vinca Institute of Nuclear Sciences, University of Belgrade, Belgrade 11001, Serbia
| | - Qianheng Du
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States.,Materials Science and Chemical Engineering Department, Stony Brook University, Stony Brook, New York 11790, United States
| | - Andreas Baum
- Walther Meissner Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.,Fakultät für Physik E23, Technische Universität München, 85748 Garching, Germany
| | - Eli Stavitski
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Yu Liu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Nenad Lazarevic
- Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
| | - Klaus Attenkofer
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Rudi Hackl
- Walther Meissner Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.,Fakultät für Physik E23, Technische Universität München, 85748 Garching, Germany
| | - Zoran Popovic
- Center for Solid State Physics and New Materials, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia.,Serbian Academy of Sciences and Arts, Kneza Mihaila 35, Belgrade 11000, Serbia
| | - Cedomir Petrovic
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States.,Materials Science and Chemical Engineering Department, Stony Brook University, Stony Brook, New York 11790, United States
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11
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Wu Y, Guo J, Li N, Li Y, Chen Y, Liang W, Zhao Y. Quasiparticle dynamics and phonon softening in FeSe 0.9S 0.1 superconductors. Phys Chem Chem Phys 2022; 24:3799-3803. [PMID: 35083986 DOI: 10.1039/d1cp04814g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The quasiparticle and longitudinal acoustic (LA) coherent phonon dynamics of the FeSe0.9S0.1 single crystal were investigated by femtosecond transient optical spectroscopy. The FeSe0.9S0.1 single crystal undergoes metal-superconductor transition at Tc = 9.5 K and structural phase transition at Ts = 72 K. To investigate the correlation between the quasiparticle/LA coherent phonon dynamics and the antiferromagnetic spin/nematic fluctuation, we measured the transient differential reflectivity ΔR(t)/R0 in time series (R is the reflectivity) between 4-130 K. The ΔR(t)/R0 time series showed a negative sign below Ts = 72 K, while its sign reversed from negative to positive above Ts. The ΔR(t)/R0 time series was contributed by a combination of two exponential decays and an oscillation term. The slow decay attributed to electron-phonon and phonon-phonon coupling showed a negative amplitude below Ts and a positive amplitude above Ts. A fast decay with positive amplitude appeared at T ≥ 55 K was induced by the electron-phonon coupling of the high-temperature orthorhombic phase FeSe0.9S0.1. The oscillation contributed by the LA coherent phonon emerged below Ts but was not observed above Ts, indicating that it was impacted by the nematic fluctuation of FeSe0.9S0.1.
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Affiliation(s)
- Yuxian Wu
- School of Physical Science and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031, China. .,Superconductivity and New Energy R&D Center, and Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, China
| | - Jia Guo
- The Peac Institute of Multiscale Sciences, Chengdu, Sichuan, China
| | - Ning Li
- The Peac Institute of Multiscale Sciences, Chengdu, Sichuan, China
| | - Yong Li
- School of Physical Science and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031, China. .,Superconductivity and New Energy R&D Center, and Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, China
| | - Yongliang Chen
- Superconductivity and New Energy R&D Center, and Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, China
| | - Weizheng Liang
- School of Physical Science and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031, China. .,The Peac Institute of Multiscale Sciences, Chengdu, Sichuan, China
| | - Yong Zhao
- School of Physical Science and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031, China. .,Superconductivity and New Energy R&D Center, and Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, China.,Fujian Provincial Collaborative Innovation Center for Advanced High-Field Superconducting Materials and Engineering, Fuzhou, Fujian 350117, China.,College of Physics and Energy, Fujian Normal University, Fuzhou, Fujian 350117, China
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12
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Krzton-Maziopa A. Intercalated Iron Chalcogenides: Phase Separation Phenomena and Superconducting Properties. Front Chem 2021; 9:640361. [PMID: 34239856 PMCID: PMC8259132 DOI: 10.3389/fchem.2021.640361] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 04/07/2021] [Indexed: 11/15/2022] Open
Abstract
Organic molecule-intercalated layered iron-based monochalcogenides are presently the subject of intense research studies due to the linkage of their fascinating magnetic and superconducting properties to the chemical nature of guests present in the structure. Iron chalcogenides have the ability to host various organic species (i.e., solvates of alkali metals and the selected Lewis bases or long-chain alkylammonium cations) between the weakly bound inorganic layers, which opens up the possibility for fine tuning the magnetic and electrical properties of the intercalated phases by controlling both the doping level and the type/shape and orientation of the organic molecules. In recent years, significant progress has been made in the field of intercalation chemistry, expanding the gallery of intercalated superconductors with new hybrid inorganic–organic phases characterized by transition temperatures to a superconducting state as high as 46 K. A typical synthetic approach involves the low-temperature intercalation of layered precursors in the presence of liquid amines, and other methods, such as electrochemical intercalation, intercalant or ion exchange, and direct solvothermal growths from anhydrous amine-based media, are also being developed. Large organic guests, while entering a layered structure on intercalation, push off the inorganic slabs and modify the geometry of their internal building blocks (edge-sharing iron chalcogenide tetrahedrons) through chemical pressure. The chemical nature and orientation of organic molecules between the inorganic layers play an important role in structural modification and may serve as a tool for the alteration of the superconducting properties. A variety of donor species well-matched with the selected alkali metals enables the adjustment of electron doping in a host structure offering a broad range of new materials with tunable electric and magnetic properties. In this review, the main aspects of intercalation chemistry are discussed, involving the influence of the chemical and electrochemical nature of intercalating species on the crystal structure and critical issues related to the superconducting properties of the hybrid inorganic–organic phases. Mutual relations between the host and organic guests lead to a specific ordering of molecular species between the host layers, and their effect on the electronic structure of the host will be also argued. A brief description of a critical assessment of the association of the most effective chemical and electrochemical methods, which lead to the preparation of nanosized/microsized powders and single crystals of molecularly intercalated phases, with the ease of preparation of phase pure materials, crystal sizes, and the morphology of final products is given together with a discussion of the stability of the intercalated materials connected with the volatility of organic solvents and a possible degradation of host materials.
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13
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Li Y, Xue J, Hu S, Pang H. Mössbauer spectroscopy study of nematicity in Ba(Fe 0.962Cu 0.038) 2As 2single crystal: enhanced orbital effect. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:205602. [PMID: 33684902 DOI: 10.1088/1361-648x/abeca7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 03/08/2021] [Indexed: 06/12/2023]
Abstract
The origin of the nematic order remains unclear due to the strong coupling between orbital, spin and lattice degrees of freedom in iron-based superconductors. Although the driving force of hole-doped BeFe2As2is still controversial, the nematic fluctuation of electron-doped compounds is generally believed to be spin fluctuation driven. Here, we present a comprehensive study of the nematic phase transition in Ba(Fe0.962Cu0.038)2As2single crystal by using Mössbauer spectroscopy. The electric field gradient and its in-plane asymmetry on Fe nucleus, which are directly determined by the occupation of individualt2gorbital, are sensitive to the local nematicity of Fe ions. The nematic phase transition happens atTnem≈ 73.8 K in the compound while the band splitting betweendxz/dyzorbitals begins far aboveTnemand reaches 18.8 meV at 30 K. The temperature evolution of the hyperfine parameters proves the existence of electron-phonon interaction and non-Fermi-liquid behaviour nearTnem. However, the spin-lattice relaxation signal is only evident belowTnem. These observations show that the role of orbital degrees of freedom is more active in driving nematicity than in Co- or Ni-doped BaFe2As2compounds, and can be attributed to enhanced electronic localization caused by Cu doping.
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Affiliation(s)
- Yang Li
- Institute of Applied Magnetics, Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000, People's Republic of China
| | - Jijun Xue
- Institute of Applied Magnetics, Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000, People's Republic of China
| | - Shixin Hu
- Institute of Applied Magnetics, Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000, People's Republic of China
| | - Hua Pang
- Institute of Applied Magnetics, Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000, People's Republic of China
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14
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Bu K, Zhang W, Fei Y, Zheng Y, Ai F, Wu Z, Wang Q, Wo H, Zhao J, Yin Y. Observation of an electronic order along [110] direction in FeSe. Nat Commun 2021; 12:1385. [PMID: 33654059 PMCID: PMC7925548 DOI: 10.1038/s41467-021-21318-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 01/17/2021] [Indexed: 11/30/2022] Open
Abstract
Multiple ordered states have been observed in unconventional superconductors. Here, we apply scanning tunneling microscopy to probe the intrinsic ordered states in FeSe, the structurally simplest iron-based superconductor. Besides the well-known nematic order along [100] direction, we observe a checkerboard charge order in the iron lattice, which we name a [110] electronic order in FeSe. The [110] electronic order is robust at 77 K, accompanied with the rather weak [100] nematic order. At 4.5 K, The [100] nematic order is enhanced, while the [110] electronic order forms domains with reduced correlation length. In addition, the collective [110] order is gaped around [−40, 40] meV at 4.5 K. The observation of this exotic electronic order may shed new light on the origin of the ordered states in FeSe. Understanding the relation of different electronic orders in high temperature superconductors is of fundamental interest. Here, the authors observe a checkerboard charge order along [110] direction of FeSe.
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Affiliation(s)
- Kunliang Bu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, China
| | - Wenhao Zhang
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, China
| | - Ying Fei
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, China
| | - Yuan Zheng
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, China
| | - Fangzhou Ai
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, China
| | - Zongxiu Wu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, China
| | - Qisi Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China
| | - Hongliang Wo
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China
| | - Jun Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Yi Yin
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, China. .,Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.
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15
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Abstract
Emergent electronic phenomena in iron-based superconductors have been at the forefront of condensed matter physics for more than a decade. Much has been learned about the origins and intertwined roles of ordered phases, including nematicity, magnetism, and superconductivity, in this fascinating class of materials. In recent years, focus has been centered on the peculiar and highly unusual properties of FeSe and its close cousins. This family of materials has attracted considerable attention due to the discovery of unexpected superconducting gap structures, a wide range of superconducting critical temperatures, and evidence for nontrivial band topology, including associated spin-helical surface states and vortex-induced Majorana bound states. Here, we review superconductivity in iron chalcogenide superconductors, including bulk FeSe, doped bulk FeSe, FeTe1−xSex, intercalated FeSe materials, and monolayer FeSe and FeTe1−xSex on SrTiO3. We focus on the superconducting properties, including a survey of the relevant experimental studies, and a discussion of the different proposed theoretical pairing scenarios. In the last part of the paper, we review the growing recent evidence for nontrivial topological effects in FeSe-related materials, focusing again on interesting implications for superconductivity.
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16
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Hong X, Caglieris F, Kappenberger R, Wurmehl S, Aswartham S, Scaravaggi F, Lepucki P, Wolter AUB, Grafe HJ, Büchner B, Hess C. Evolution of the Nematic Susceptibility in LaFe_{1-x}Co_{x}AsO. PHYSICAL REVIEW LETTERS 2020; 125:067001. [PMID: 32845654 DOI: 10.1103/physrevlett.125.067001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 06/26/2020] [Accepted: 07/07/2020] [Indexed: 06/11/2023]
Abstract
We report a systematic elastoresistivity study on LaFe_{1-x}Co_{x}AsO single crystals, which have well separated structural and magnetic transition lines. All crystals show a Curie-Weiss-like nematic susceptibility in the tetragonal phase. The extracted nematic temperature is monotonically suppressed upon cobalt doping, and changes sign around the optimal doping level, indicating a possible nematic quantum critical point beneath the superconducting dome. The amplitude of the nematic susceptibility shows a peculiar double-peak feature. This could be explained by a combined effect of different contributions to the nematic susceptibility, which are amplified at separated doping levels of LaFe_{1-x}Co_{x}AsO.
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Affiliation(s)
- Xiaochen Hong
- Leibniz-Institute for Solid State and Materials Research (IFW Dresden), 01069 Dresden, Germany
| | - Federico Caglieris
- Leibniz-Institute for Solid State and Materials Research (IFW Dresden), 01069 Dresden, Germany
| | - Rhea Kappenberger
- Leibniz-Institute for Solid State and Materials Research (IFW Dresden), 01069 Dresden, Germany
| | - Sabine Wurmehl
- Leibniz-Institute for Solid State and Materials Research (IFW Dresden), 01069 Dresden, Germany
| | - Saicharan Aswartham
- Leibniz-Institute for Solid State and Materials Research (IFW Dresden), 01069 Dresden, Germany
| | - Francesco Scaravaggi
- Leibniz-Institute for Solid State and Materials Research (IFW Dresden), 01069 Dresden, Germany
- Institute of Solid State and Materials Physics, Technische Universität Dresden, 01069 Dresden, Germany
| | - Piotr Lepucki
- Leibniz-Institute for Solid State and Materials Research (IFW Dresden), 01069 Dresden, Germany
| | - Anja U B Wolter
- Leibniz-Institute for Solid State and Materials Research (IFW Dresden), 01069 Dresden, Germany
| | - Hans-Joachim Grafe
- Leibniz-Institute for Solid State and Materials Research (IFW Dresden), 01069 Dresden, Germany
| | - Bernd Büchner
- Leibniz-Institute for Solid State and Materials Research (IFW Dresden), 01069 Dresden, Germany
- Institute of Solid State and Materials Physics, Technische Universität Dresden, 01069 Dresden, Germany
- Center for Transport and Devices, Technische Universität Dresden, 01069 Dresden, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
| | - Christian Hess
- Leibniz-Institute for Solid State and Materials Research (IFW Dresden), 01069 Dresden, Germany
- Center for Transport and Devices, Technische Universität Dresden, 01069 Dresden, Germany
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17
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Tranquada JM, Xu G, Zaliznyak IA. Magnetism and superconductivity in Fe 1+y Te 1-xSe x. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:374003. [PMID: 31412327 DOI: 10.1088/1361-648x/ab3b3b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 08/14/2019] [Indexed: 06/10/2023]
Abstract
Neutron scattering has played a significant role in characterizing magnetic and structural correlations in Fe1+y Te1-xSexand their connections with superconductivity. Here we review several key aspects of the physics of iron chalcogenide superconductors where neutron studies played a key role. These topics include the phase diagram of Fe1+y Te1-xSex, where the doping-dependence of structural transitions can be understood from a mapping to the anisotropic random field Ising model. We then discuss orbital-selective Mott physics in the Fe chalcogenide series, where temperature-dependent magnetism in the parent material provided one of the earliest cases for orbital-selective correlation effects in a Hund's metal. Finally, we elaborate on the character of local magnetic correlations revealed by neutron scattering, its dependence on temperature and composition, and the connections to nematicity and superconductivity.
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Affiliation(s)
- J M Tranquada
- Brookhaven National Laboratory, Condensed Matter & Materials Science Division, Upton, NY 11973-5000, United States of America
| | - Guangyong Xu
- NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, United States of America
| | - I A Zaliznyak
- Brookhaven National Laboratory, Condensed Matter & Materials Science Division, Upton, NY 11973-5000, United States of America
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18
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Xu X, Zhang S, Zhu X, Guo J. Superconductivity enhancement in FeSe/SrTiO 3: a review from the perspective of electron-phonon coupling. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:343003. [PMID: 32241002 DOI: 10.1088/1361-648x/ab85f0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 04/02/2020] [Indexed: 06/11/2023]
Abstract
Single-layer FeSe films grown on SrTiO3, with the highest superconducting transition temperature (TC) among all the iron-based superconductors, serves as an ideal platform for studying the microscopic mechanisms of high-TCsuperconductivity. The significant role of interfacial coupling has been widely recognized, while the precise nature of theTCenhancement remains open. In this review, we focus on the investigations of the interfacial coupling in FeSe/SrTiO3from the perspective of electron-phonon coupling (EPC). The main content will include an overview of the experimental measurements associated with different theoretical models and arguments about the EPC. Especially, besides the discussions of EPC based on the measurements of electronic states, we will emphasize the analyses based on phonon measurements. A uniform picture about the nature of the EPC and its relation to theTCenhancement in FeSe/SrTiO3has still not achieved, which should be the key for further studies aiming to the in-depth understanding of high-TCsuperconductivity and the discovery of new superconductors with even enhancedTC.
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Affiliation(s)
- Xiaofeng Xu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Shuyuan Zhang
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York 14853, United States of America
| | - Xuetao Zhu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Jiandong Guo
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China
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19
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Song SY, Martiny JHJ, Kreisel A, Andersen BM, Seo J. Visualization of Local Magnetic Moments Emerging from Impurities in Hund's Metal States of FeSe. PHYSICAL REVIEW LETTERS 2020; 124:117001. [PMID: 32242691 DOI: 10.1103/physrevlett.124.117001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 09/30/2019] [Accepted: 02/21/2020] [Indexed: 06/11/2023]
Abstract
Understanding the origin of the magnetism of high temperature superconductors is crucial for establishing their unconventional pairing mechanism. Recently, theory predicts that FeSe is close to a magnetic quantum critical point, and thus weak perturbations such as impurities could induce local magnetic moments. To elucidate such quantum instability, we have employed scanning tunneling microscopy and spectroscopy. In particular, we have grown FeSe film on superconducting Pb(111) using molecular beam epitaxy and investigated magnetic excitation caused by impurities in the proximity-induced superconducting gap of FeSe. Our study provides deep insight into the origin of the magnetic ordering of FeSe by showing the way local magnetic moments develop in response to impurities near the magnetic quantum critical point.
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Affiliation(s)
- Sang Yong Song
- Department of Emerging Materials Science, DGIST, 333 Techno-Jungang-daero, Hyeonpung-Eup, Dalseong-Gun, Daegu 42988, Korea
| | - J H J Martiny
- Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - A Kreisel
- Institut für Theoretische Physik, Universität Leipzig, D-04103 Leipzig, Germany
| | - B M Andersen
- Niels Bohr Institute, University of Copenhagen, Lyngbyvej 2, DK-2100 Copenhagen, Denmark
| | - Jungpil Seo
- Department of Emerging Materials Science, DGIST, 333 Techno-Jungang-daero, Hyeonpung-Eup, Dalseong-Gun, Daegu 42988, Korea
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20
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Wilfong B, Zhou X, Zheng H, Babra N, Brown CM, Lynn JW, Taddei KM, Paglione J, Rodriguez EE. Long-range magnetic order in hydroxide-layer-doped (Li 1-x-y Fe x Mn y OD)FeSe. PHYSICAL REVIEW MATERIALS 2020; 4:10.1103/PhysRevMaterials.4.034803. [PMID: 34142003 PMCID: PMC8207456 DOI: 10.1103/physrevmaterials.4.034803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The (Li1-x Fe x OH)FeSe superconductor has been suspected of exhibiting long-range magnetic ordering due to Fe substitution in the LiOH layer. However, no direct observation such as magnetic reflection from neutron diffraction has been reported. Here, we use a chemical design strategy to manipulate the doping level of transition metals in the LiOH layer to tune the magnetic properties of the (Li1-x-y Fe x Mn y OD)FeSe system. We find Mn doping exclusively replaces Li in the hydroxide layer resulting in enhanced magnetization in the (Li0.876Fe0.062Mn0.062OD)FeSe superconductor without significantly altering the superconducting behavior as resolved by magnetic susceptibility and electrical/thermal transport measurements. As a result, long-range magnetic ordering was observed below 12 K with neutron diffraction measurements. This work has implications for the design of magnetic superconductors for the fundamental understanding of superconductivity and magnetism in the iron chalcogenide system as well as exploitation as functional materials for next-generation devices.
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Affiliation(s)
- Brandon Wilfong
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
- Maryland Quantum Materials Center, University of Maryland, College Park, Maryland 20742, USA
| | - Xiuquan Zhou
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Huafei Zheng
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | - Navneeth Babra
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | - Craig M. Brown
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Jeffrey W. Lynn
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Keith M. Taddei
- Diffraction Group, Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Johnpierre Paglione
- Maryland Quantum Materials Center, University of Maryland, College Park, Maryland 20742, USA
- Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - Efrain E. Rodriguez
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
- Maryland Quantum Materials Center, University of Maryland, College Park, Maryland 20742, USA
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21
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Chen T, Chen Y, Tam DW, Gao B, Qiu Y, Schneidewind A, Radelytskyi I, Prokes K, Chi S, Matsuda M, Broholm C, Dai P. Anisotropic effect of a magnetic field on the neutron spin resonance in FeSe. PHYSICAL REVIEW. B 2020; 101:10.1103/physrevb.101.140504. [PMID: 33655092 PMCID: PMC7918269 DOI: 10.1103/physrevb.101.140504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We use inelastic neutron scattering to study the effect of a magnetic field on the neutron spin resonance (E r = 3.6 meV) of superconducting FeSe (T c = 9 K). While a field aligned along the in-plane direction broadens and suppresses the resonance, a c-axis aligned field does so much more efficiently, consistent with the anisotropic field-induced suppression of the superfluid density from the heat capacity measurements. These results suggest that the resonance in FeSe is associated with the superconducting electrons arising from orbital selective quasiparticle excitations between the hole and electron Fermi surfaces.
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Affiliation(s)
- Tong Chen
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Youzhe Chen
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - David W. Tam
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Bin Gao
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Yiming Qiu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Astrid Schneidewind
- Jülich Center for Neutron Sciences, Forschungszentrum Jülich GmbH, Outstation at MLZ, D-85747 Garching, Germany
| | - Igor Radelytskyi
- Jülich Center for Neutron Sciences, Forschungszentrum Jülich GmbH, Outstation at MLZ, D-85747 Garching, Germany
| | - Karel Prokes
- Helmholtz Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany
| | - Songxue Chi
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Masaaki Matsuda
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Collin Broholm
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
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22
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Wang X, Yuan Y, Xue QK, Li W. Charge ordering in high-temperature superconductors visualized by scanning tunneling microscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:013002. [PMID: 31487703 DOI: 10.1088/1361-648x/ab41c5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Since the discovery of stripe order in La1.6-x Nd0.4Sr x CuO4 superconductors in 1995, charge ordering in cuprate superconductors has been intensively studied by various experimental techniques. Among these studies, scanning tunneling microscope (STM) plays an irreplaceable role in determining the real space structures of charge ordering. STM imaging of different families of cuprates over a wide range of doping levels reveal similar checkerboard-like patterns, indicating that such a charge ordered state is likely a ubiquitous and intrinsic characteristic of cuprate superconductors, which may shed light on understanding the mechanism of high-temperature superconductivity. In another class of high-temperature superconductors, iron-based superconductors, STM studies reveal several charge ordered states as well, but their real-space patterns and the interplay with superconductivity are markedly different among different materials. In this paper, we present a brief review on STM studies of charge ordering in these two classes of high-temperature superconductors. Possible origins of charge ordering and its interplay with superconductivity will be discussed.
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Affiliation(s)
- Xintong Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China. Collaborative Innovation Center of Quantum Matter, Beijing 100084, People's Republic of China
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23
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Huang Y, Hu Y, Hu F, Yang R, Li C, Armstrong JN, Ren S. Correlation at two-dimensional charge-transfer FeSe interface. Chem Commun (Camb) 2019; 55:12643-12646. [PMID: 31580340 DOI: 10.1039/c9cc06163k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The charge transfer and spin coupling effects are explored at the interface of two-dimensional (2D) superconducting FeSe nanosheets and molecular photochromic potassium-7,7,8,8-tetracyanoquinodimethane (KTCNQ). Light-induced conductivity in 2D FeSe nanosheets is enhanced by the electron doping from KTCNQ by the destabilized spin-Peierls phase through their interface. Furthermore, the spin coupling at the interface of FeSe and KTCNQ shifts the dimerization transition temperature of KTCNQ. Our results suggest 2D exfoliated FeSe nanosheets as a versatile strongly correlated platform for the study of interfacial electron doping and spin coupling.
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Affiliation(s)
- Yulong Huang
- Department of Mechanical and Aerospace Engineering, Research and Education in Energy Environment & Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
| | - Yong Hu
- Department of Mechanical and Aerospace Engineering, Research and Education in Energy Environment & Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
| | - Feng Hu
- Department of Mechanical and Aerospace Engineering, Research and Education in Energy Environment & Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
| | - Ruizhe Yang
- Department of Mechanical and Aerospace Engineering, Research and Education in Energy Environment & Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
| | - Changning Li
- Department of Mechanical and Aerospace Engineering, Research and Education in Energy Environment & Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
| | - Jason N Armstrong
- Department of Mechanical and Aerospace Engineering, Research and Education in Energy Environment & Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
| | - Shenqiang Ren
- Department of Mechanical and Aerospace Engineering, Research and Education in Energy Environment & Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA.
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24
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Chen T, Chen Y, Kreisel A, Lu X, Schneidewind A, Qiu Y, Park JT, Perring TG, Stewart JR, Cao H, Zhang R, Li Y, Rong Y, Wei Y, Andersen BM, Hirschfeld PJ, Broholm C, Dai P. Anisotropic spin fluctuations in detwinned FeSe. NATURE MATERIALS 2019; 18:709-716. [PMID: 31110345 PMCID: PMC7895486 DOI: 10.1038/s41563-019-0369-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 04/10/2019] [Indexed: 05/05/2023]
Abstract
Superconductivity in FeSe emerges from a nematic phase that breaks four-fold rotational symmetry in the iron plane. This phase may arise from orbital ordering, spin fluctuations or hidden magnetic quadrupolar order. Here we use inelastic neutron scattering on a mosaic of single crystals of FeSe, detwinned by mounting on a BaFe2As2 substrate to demonstrate that spin excitations are most intense at the antiferromagnetic wave vectors QAF = (±1, 0) at low energies E = 6-11 meV in the normal state. This two-fold (C2) anisotropy is reduced at lower energies, 3-5 meV, indicating a gapped four-fold (C4) mode. In the superconducting state, however, the strong nematic anisotropy is again reflected in the spin resonance (E = 3.6 meV) at QAF with incommensurate scattering around 5-6 meV. Our results highlight the extreme electronic anisotropy of the nematic phase of FeSe and are consistent with a highly anisotropic superconducting gap driven by spin fluctuations.
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Affiliation(s)
- Tong Chen
- Department of Physics and Astronomy, Rice University, Houston, TX, USA
| | - Youzhe Chen
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA
| | - Andreas Kreisel
- Institut für Theoretische Physik, Universität Leipzig, Leipzig, Germany
| | - Xingye Lu
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing, China.
| | - Astrid Schneidewind
- Forschungszentrum Jülich GmbH, Jülich Center for Neutron Sciences at MLZ, Garching, Germany
| | - Yiming Qiu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - J T Park
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Garching, Germany
| | - Toby G Perring
- ISIS Facility, STFC Rutherford-Appleton Laboratory, Didcot, UK
| | - J Ross Stewart
- ISIS Facility, STFC Rutherford-Appleton Laboratory, Didcot, UK
| | - Huibo Cao
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Rui Zhang
- Department of Physics and Astronomy, Rice University, Houston, TX, USA
| | - Yu Li
- Department of Physics and Astronomy, Rice University, Houston, TX, USA
| | - Yan Rong
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing, China
| | - Yuan Wei
- Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Brian M Andersen
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - P J Hirschfeld
- Department of Physics, University of Florida, Gainesville, FL, USA
| | - Collin Broholm
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, TX, USA.
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing, China.
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25
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Wo H, Wang Q, Shen Y, Zhang X, Hao Y, Feng Y, Shen S, He Z, Pan B, Wang W, Nakajima K, Ohira-Kawamura S, Steffens P, Boehm M, Schmalzl K, Forrest TR, Matsuda M, Zhao Y, Lynn JW, Yin Z, Zhao J. Coexistence of Ferromagnetic and Stripe-Type Antiferromagnetic Spin Fluctuations in YFe_{2}Ge_{2}. PHYSICAL REVIEW LETTERS 2019; 122:217003. [PMID: 31283313 PMCID: PMC11280088 DOI: 10.1103/physrevlett.122.217003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 04/02/2019] [Indexed: 06/09/2023]
Abstract
We report neutron scattering measurements of single-crystalline YFe_{2}Ge_{2} in the normal state, which has the same crystal structure as the 122 family of iron pnictide superconductors. YFe_{2}Ge_{2} does not exhibit long-range magnetic order but exhibits strong spin fluctuations. Like the iron pnictides, YFe_{2}Ge_{2} displays anisotropic stripe-type antiferromagnetic spin fluctuations at (π, 0, π). More interesting, however, is the observation of strong spin fluctuations at the in-plane ferromagnetic wave vector (0, 0, π). These ferromagnetic spin fluctuations are isotropic in the (H, K) plane, whose intensity exceeds that of stripe spin fluctuations. Both the ferromagnetic and stripe spin fluctuations remain gapless down to the lowest measured energies. Our results naturally explain the absence of magnetic order in YFe_{2}Ge_{2} and also imply that the ferromagnetic correlations may be a key ingredient for iron-based materials.
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Affiliation(s)
- Hongliang Wo
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Qisi Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yao Shen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Xiaowen Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yiqing Hao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yu Feng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Shoudong Shen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Zheng He
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Bingying Pan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Wenbin Wang
- Institute of Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - K. Nakajima
- Materials and Life Science Division, J-PARC Center, Tokai, Ibaraki 319-1195, Japan
| | - S. Ohira-Kawamura
- Materials and Life Science Division, J-PARC Center, Tokai, Ibaraki 319-1195, Japan
| | - P. Steffens
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - M. Boehm
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - K. Schmalzl
- Forschungszentrum Jülich GmbH. Jülich Centre for Neutron Science at ILL, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - T. R. Forrest
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, United Kingdom
| | - M. Matsuda
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Yang Zhao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - J. W. Lynn
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Zhiping Yin
- Department of Physics and Center for Advanced Quantum Studies, Beijing Normal University, Beijing 100875, China
| | - Jun Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing, 210093, China
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26
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Song Y, Cao H, Chakoumakos BC, Zhao Y, Wang A, Lei H, Petrovic C, Birgeneau RJ. Intertwined Magnetic and Nematic Orders in Semiconducting KFe_{0.8}Ag_{1.2}Te_{2}. PHYSICAL REVIEW LETTERS 2019; 122:087201. [PMID: 30932606 DOI: 10.1103/physrevlett.122.087201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 11/27/2018] [Indexed: 06/09/2023]
Abstract
Superconductivity in the iron pnictides emerges from metallic parent compounds exhibiting intertwined stripe-type magnetic order and nematic order, with itinerant electrons suggested to be essential for both. Here we use x-ray and neutron scattering to show that a similar intertwined state is realized in semiconducting KFe_{0.8}Ag_{1.2}Te_{2} (K_{5}Fe_{4}Ag_{6}Te_{10}) without itinerant electrons. We find that Fe atoms in KFe_{0.8}Ag_{1.2}Te_{2} form isolated 2×2 blocks, separated by nonmagnetic Ag atoms. Long-range magnetic order sets in below T_{N}≈35 K, with magnetic moments within the 2×2 Fe blocks ordering into the stripe-type configuration. A nematic order accompanies the magnetic transition, manifest as a structural distortion that breaks the fourfold rotational symmetry of the lattice. The nematic orders in KFe_{0.8}Ag_{1.2}Te_{2} and iron pnictide parent compounds are similar in magnitude and in how they relate to the magnetic order, indicating a common origin. Since KFe_{0.8}Ag_{1.2}Te_{2} is a semiconductor without itinerant electrons, this indicates that local-moment magnetic interactions are integral to its magnetic and nematic orders, and such interactions may play a key role in iron-based superconductivity.
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Affiliation(s)
- Yu Song
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Huibo Cao
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - B C Chakoumakos
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Yang Zhao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - Aifeng Wang
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Hechang Lei
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - C Petrovic
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Robert J Birgeneau
- Department of Physics, University of California, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
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27
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Sluchanko NE, Azarevich AN, Bogach AV, Bolotina NB, Glushkov VV, Demishev SV, Dudka AP, Khrykina ON, Filipov VB, Shitsevalova NY, Komandin GA, Muratov AV, Aleshchenko YA, Zhukova ES, Gorshunov BP. Observation of dynamic charge stripes in Tm 0.19Yb 0.81B 12 at the metal-insulator transition. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:065604. [PMID: 30524111 DOI: 10.1088/1361-648x/aaf44e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Accurate low temperature charge transport measurements in combination with high-precision x-ray diffraction experiments have allowed detection of the symmetry lowering in the single domain Tm0.19Yb0.81B12 crystals that belong to the family of dodecaborides with metal-insulator transition. Based on the fine structure analysis we discover the formation of dynamic charge stripes within the semiconducting matrix of Tm0.19Yb0.81B12. The charge dynamics in these conducting nano-size channels is characterized by broad-band optical spectroscopy that allowed estimating the frequency (~2.4 × 1011 Hz) of quantum motion of the charge carriers. It is suggested that cooperative Jahn-Teller effect in the boron sublattice is a cause of the large-amplitude rattling modes of the Tm and Yb ions responsible for the 'modulation' of the conduction band along one of the [Formula: see text] directions through the variation of 5d-2p hybridization of electron states.
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Affiliation(s)
- N E Sluchanko
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov str. 38, Moscow 119991, Russia. Moscow Institute of Physics and Technology, 9, Institutskii per., Dolgoprudnyi, Moscow region 141700, Russia
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28
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She JH, Lawler MJ, Kim EA. Quantum Spin Liquid Intertwining Nematic and Superconducting Order in Fese. PHYSICAL REVIEW LETTERS 2018; 121:237002. [PMID: 30576170 DOI: 10.1103/physrevlett.121.237002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 02/19/2018] [Indexed: 06/09/2023]
Abstract
Despite its seemingly simple composition and structure, the pairing mechanism of FeSe remains an open problem due to several striking phenomena. Among them are nematic order without magnetic order, nodeless gap and unusual inelastic neutron spectra with a broad continuum, and gap anisotropy consistent with orbital selection of unknown origin. Here we propose a microscopic description of a nematic quantum spin liquid that reproduces key features of neutron spectra. We then study how the spin fluctuations of the local moments lead to pairing within a spin-fermion model. We find the resulting superconducting order parameter to be nodeless s±d wave within each domain. Further we show that orbital dependent Kondo-like coupling can readily capture observed gap anisotropy. Our prediction calls for inelastic neutron scattering in a detwinned sample.
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Affiliation(s)
- Jian-Huang She
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - Michael J Lawler
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
- Department of physics, Binghamton University, Vestal, New York 13850, USA
- Kavli Institute for Theoretical Physics, Kohn Hall, University of California, Santa Barbara, California 93106-4030, USA
| | - Eun-Ah Kim
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
- Kavli Institute for Theoretical Physics, Kohn Hall, University of California, Santa Barbara, California 93106-4030, USA
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29
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Chen L, Zhao WW, Han RS. Resonance states near a quantum magnetic impurity in single-layer FeSe superconductors with d-wave symmetry. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:305603. [PMID: 29911989 DOI: 10.1088/1361-648x/aacd37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In this work, we investigate the local density of states (LDOS) near a magnetic impurity in single-layer FeSe superconductors. The two-orbital model with spin-orbit coupling proposed in Agterberg et al (2017 Phys. Rev. Lett. 119 267001) is used to describe the FeSe superconductor. In the strong coupling regime, two impurity resonance peaks appear with opposite resonance energies in the LDOS spectral function. For strong spin-orbit coupling, the superconducting gap in this model is d-wave symmetric with nodes, the spatial distributions of the LDOS at the two resonance energies are fourfold symmetric, which reveals typical characteristic of d-wave pairing. When the spin-orbit coupling is not strong enough to close the superconducting gap, we find that the spatial distribution of the LDOS at one of the resonance energies manifests s-wave symmetry, while the pairing potential preserves d-wave symmetry. This result is consistent with previous experimental investigations.
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Affiliation(s)
- Liang Chen
- Mathematics and Physics Department, North China Electric Power University, Beijing, 102206, People's Republic of China
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30
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Kang J, Fernandes RM, Chubukov A. Superconductivity in FeSe: The Role of Nematic Order. PHYSICAL REVIEW LETTERS 2018; 120:267001. [PMID: 30004771 DOI: 10.1103/physrevlett.120.267001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Indexed: 06/08/2023]
Abstract
Bulk FeSe is a special iron-based material in which superconductivity emerges inside a well-developed nematic phase. We present a microscopic model for this nematic superconducting state, which takes into account the mixing between s-wave and d-wave pairing channels and the changes in the orbital spectral weight promoted by the sign-changing nematic order parameter. We show that nematicity only weakly affects T_{c}, but gives rise to cos2θ variation of the pairing gap on the hole pocket, whose magnitude and size agrees with angle resolved photoemission spectroscopy and STM data. We further show that nematicity increases the weight of the d_{xz} orbital on the hole pocket, and increases (reduces) the weight of the d_{xy} orbital on the Y (X) electron pocket.
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Affiliation(s)
- Jian Kang
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32304, USA
| | - Rafael M Fernandes
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Andrey Chubukov
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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31
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Xie T, Wei Y, Gong D, Fennell T, Stuhr U, Kajimoto R, Ikeuchi K, Li S, Hu J, Luo H. Odd and Even Modes of Neutron Spin Resonance in the Bilayer Iron-Based Superconductor CaKFe_{4}As_{4}. PHYSICAL REVIEW LETTERS 2018; 120:267003. [PMID: 30004765 DOI: 10.1103/physrevlett.120.267003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Indexed: 06/08/2023]
Abstract
We report an inelastic neutron scattering study on the spin resonance in the bilayer iron-based superconductor CaKFe_{4}As_{4}. In contrast to its quasi-two-dimensional electron structure, three strongly L-dependent modes of spin resonance are found below T_{c}=35 K. The mode energies are below and linearly scale with the total superconducting gaps summed on the nesting hole and electron pockets, essentially in agreement with the results in cuprate and heavy fermion superconductors. This observation supports the sign-reversed Cooper pairing mechanism under multiple pairing channels and resolves the long-standing puzzles concerning the broadening and dispersive spin resonance peak in iron pnictides. More importantly, the triple resonant modes can be classified into odd and even symmetries with respect to the distance of Fe-Fe planes within the Fe-As bilayer unit. Thus, our results closely resemble those in the bilayer cuprates with nondegenerate spin excitations, suggesting that these two high-T_{c} superconducting families share a common nature.
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Affiliation(s)
- Tao Xie
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuan Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dongliang Gong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tom Fennell
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Uwe Stuhr
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Ryoichi Kajimoto
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Kazuhiko Ikeuchi
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, Tokai, Ibaraki 319-1106, Japan
| | - Shiliang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - Jiangping Hu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - Huiqian Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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32
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Krzton-Maziopa A, Pesko E, Puzniak R. Superconducting selenides intercalated with organic molecules: synthesis, crystal structure, electric and magnetic properties, superconducting properties, and phase separation in iron based-chalcogenides and hybrid organic-inorganic superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:243001. [PMID: 29664412 DOI: 10.1088/1361-648x/aabeb5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Layered iron-based superconducting chalcogenides intercalated with molecular species are the subject of intensive studies, especially in the field of solid state chemistry and condensed matter physics, because of their intriguing chemistry and tunable electric and magnetic properties. Considerable progress in the research, revealing superconducting inorganic-organic hybrid materials with transition temperatures to superconducting state, T c, up to 46 K, has been brought in recent years. These novel materials are synthesized by low-temperature intercalation of molecular species, such as solvates of alkali metals and nitrogen-containing donor compounds, into layered FeSe-type structure. Both the chemical nature as well as orientation of organic molecules between the layers of inorganic host, play an important role in structural modifications and may be used for fine tuning of superconducting properties. Furthermore, a variety of donor species compatible with alkali metals, as well as the possibility of doping also in the host structure (either on Fe or Se sites), makes this system quite flexible and gives a vast array of new materials with tunable electric and magnetic properties. In this review, the main aspects of intercalation chemistry are discussed with a particular attention paid to the influence of the unique nature of intercalating species on the crystal structure and physical properties of the hybrid inorganic-organic materials. To get a full picture of these materials, a comprehensive description of the most effective chemical and electrochemical methods, utilized for synthesis of intercalated species, with critical evaluation of their strong and weak points, related to feasibility of synthesis, phase purity, crystal size and morphology of final products, is included as well.
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Affiliation(s)
- Anna Krzton-Maziopa
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, PL-00-664 Warsaw, Poland
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33
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Meng L, Yu J, Peng H, Li Y, Zhong JX. A novel metastable state magnetic phase of monolayer FeSe. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:155804. [PMID: 29504944 DOI: 10.1088/1361-648x/aab40d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We found a novel metastable magnetic phase by systematically calculating total energy of monolayer FeSe in various antiferromagnetic (AFM) orders using first-principles method. The new metastable magnetic phase named as QAFM is a magnetic state with short-range magnetic structure which can be regarded as a transitional state between checkerboard-like AFM state and collinear AFM state. Both magnetic moments with important fluctuation and charge density difference with a 2 × 4 reconstruction of orbitals breaks C 4 symmetry and possibly commonly corresponds to the nematic phase in recent transmission electron microscopy and neutron scattering experiment observations. Its electronic band displays a Dirac-like band structure along Γ-X in the folding Brillouin zone of the supercell. The QAFM phase of FeSe holds metallic feature with d xz , d yz and [Formula: see text] band crossing Fermi level even including spin-orbit coupling. Additionally, the weight of 3d orbitals varies as the applied expansion strain which may be directly correlated with the emerging nematic phase and superconducting state of strained monolayer FeSe. The finding of novel magnetic order may provide important clues to elucidate the relationship of antiferromagnetism and superconductivity for unconventional Fe-based superconductor.
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Affiliation(s)
- Lijun Meng
- Hunan Key Laboratory for Micro-Nano Energy Materials and Devices, School of Physics and Optoelectronics, Xiangtan University, Xiangtan 411105, Hunan, People's Republic of China
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34
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Xie T, Gong D, Ghosh H, Ghosh A, Soda M, Masuda T, Itoh S, Bourdarot F, Regnault LP, Danilkin S, Li S, Luo H. Neutron Spin Resonance in the 112-Type Iron-Based Superconductor. PHYSICAL REVIEW LETTERS 2018; 120:137001. [PMID: 29694229 DOI: 10.1103/physrevlett.120.137001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Indexed: 06/08/2023]
Abstract
We use inelastic neutron scattering to study the low-energy spin excitations of the 112-type iron pnictide Ca_{0.82}La_{0.18}Fe_{0.96}Ni_{0.04}As_{2} with bulk superconductivity below T_{c}=22 K. A two-dimensional spin resonance mode is found around E=11 meV, where the resonance energy is almost temperature independent and linearly scales with T_{c} along with other iron-based superconductors. Polarized neutron analysis reveals the resonance is nearly isotropic in spin space without any L modulations. Because of the unique monoclinic structure with additional zigzag arsenic chains, the As 4p orbitals contribute to a three-dimensional hole pocket around the Γ point and an extra electron pocket at the X point. Our results suggest that the energy and momentum distribution of the spin resonance does not directly respond to the k_{z} dependence of the fermiology, and the spin resonance intrinsically is a spin-1 mode from singlet-triplet excitations of the Cooper pairs in the case of weak spin-orbital coupling.
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Affiliation(s)
- Tao Xie
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dongliang Gong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Haranath Ghosh
- Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India
- Human Resources development section, Raja Ramanna Centre for Advanced Technology, Indore 452013, India
| | - Abyay Ghosh
- Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India
- Human Resources development section, Raja Ramanna Centre for Advanced Technology, Indore 452013, India
| | - Minoru Soda
- The Institute for Solid State Physics, The University of Tokyo, Chiba 277-8581, Japan
| | - Takatsugu Masuda
- The Institute for Solid State Physics, The University of Tokyo, Chiba 277-8581, Japan
| | - Shinichi Itoh
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan
| | | | - Louis-Pierre Regnault
- Intitut Laue Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble Cedex, France
| | - Sergey Danilkin
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234, Australia
| | - Shiliang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - Huiqian Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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35
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Zhou Y, Miao L, Wang P, Zhu FF, Jiang WX, Jiang SW, Zhang Y, Lei B, Chen XH, Ding HF, Zheng H, Zhang WT, Jia JF, Qian D, Wu D. Antiferromagnetic Order in Epitaxial FeSe Films on SrTiO_{3}. PHYSICAL REVIEW LETTERS 2018; 120:097001. [PMID: 29547312 DOI: 10.1103/physrevlett.120.097001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Indexed: 06/08/2023]
Abstract
Single monolayer FeSe film grown on a Nb-doped SrTiO_{3}(001) substrate shows the highest superconducting transition temperature (T_{C}∼100 K) among the iron-based superconductors (iron pnictides), while the T_{C} value of bulk FeSe is only ∼8 K. Although bulk FeSe does not show antiferromagnetic order, calculations suggest that the parent FeSe/SrTiO_{3} films are antiferromagnetic. Experimentally, because of a lack of a direct probe, the magnetic state of FeSe/SrTiO_{3} films remains mysterious. Here, we report direct evidence of antiferromagnetic order in the parent FeSe/SrTiO_{3} films by the magnetic exchange bias effect measurements. The magnetic blocking temperature is ∼140 K for a single monolayer film. The antiferromagnetic order disappears after electron doping.
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Affiliation(s)
- Y Zhou
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - L Miao
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - P Wang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - F F Zhu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - W X Jiang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - S W Jiang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Y Zhang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - B Lei
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, Hefei, Anhui 230026, China
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - X H Chen
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, Hefei, Anhui 230026, China
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - H F Ding
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Hao Zheng
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - W T Zhang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Jin-Feng Jia
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Dong Qian
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - D Wu
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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36
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Böhmer AE, Kreisel A. Nematicity, magnetism and superconductivity in FeSe. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:023001. [PMID: 29240560 DOI: 10.1088/1361-648x/aa9caa] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Iron-based superconductors are well known for their complex interplay between structure, magnetism and superconductivity. FeSe offers a particularly fascinating example. This material has been intensely discussed because of its extended nematic phase, whose relationship with magnetism is not obvious. Superconductivity in FeSe is highly tunable, with the superconducting transition temperature, T c, ranging from 8 K in bulk single crystals at ambient pressure to almost 40 K under pressure or in intercalated systems, and to even higher temperatures in thin films. In this topical review, we present an overview of nematicity, magnetism and superconductivity, and discuss the interplay of these phases in FeSe. We focus on bulk FeSe and the effects of physical pressure and chemical substitutions as tuning parameters. The experimental results are discussed in the context of the well-studied iron-pnictide superconductors and interpretations from theoretical approaches are presented.
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Affiliation(s)
- Anna E Böhmer
- Ames Laboratory, US DOE, Ames, IA 50011, United States of America
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37
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Gerber S, Yang SL, Zhu D, Soifer H, Sobota JA, Rebec S, Lee JJ, Jia T, Moritz B, Jia C, Gauthier A, Li Y, Leuenberger D, Zhang Y, Chaix L, Li W, Jang H, Lee JS, Yi M, Dakovski GL, Song S, Glownia JM, Nelson S, Kim KW, Chuang YD, Hussain Z, Moore RG, Devereaux TP, Lee WS, Kirchmann PS, Shen ZX. Femtosecond electron-phonon lock-in by photoemission and x-ray free-electron laser. Science 2018; 357:71-75. [PMID: 28684521 DOI: 10.1126/science.aak9946] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 05/03/2017] [Indexed: 11/02/2022]
Abstract
The interactions that lead to the emergence of superconductivity in iron-based materials remain a subject of debate. It has been suggested that electron-electron correlations enhance electron-phonon coupling in iron selenide (FeSe) and related pnictides, but direct experimental verification has been lacking. Here we show that the electron-phonon coupling strength in FeSe can be quantified by combining two time-domain experiments into a "coherent lock-in" measurement in the terahertz regime. X-ray diffraction tracks the light-induced femtosecond coherent lattice motion at a single phonon frequency, and photoemission monitors the subsequent coherent changes in the electronic band structure. Comparison with theory reveals a strong enhancement of the coupling strength in FeSe owing to correlation effects. Given that the electron-phonon coupling affects superconductivity exponentially, this enhancement highlights the importance of the cooperative interplay between electron-electron and electron-phonon interactions.
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Affiliation(s)
- S Gerber
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA.,SwissFEL and Laboratory for Micro and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - S-L Yang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA.,Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - D Zhu
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - H Soifer
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA
| | - J A Sobota
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA.,Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - S Rebec
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA.,Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - J J Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA.,Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - T Jia
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA.,Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - B Moritz
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA
| | - C Jia
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA
| | - A Gauthier
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA.,Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Y Li
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA
| | - D Leuenberger
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA
| | - Y Zhang
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - L Chaix
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA
| | - W Li
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA
| | - H Jang
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - J-S Lee
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - M Yi
- Department of Physics, University of California-Berkeley, Berkeley, CA 94720, USA
| | - G L Dakovski
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - S Song
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - J M Glownia
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - S Nelson
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - K W Kim
- Department of Physics, Chungbuk National University, Cheongju 28644, Korea
| | - Y-D Chuang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Z Hussain
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - R G Moore
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA
| | - T P Devereaux
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA
| | - W-S Lee
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA.
| | - P S Kirchmann
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA.
| | - Z-X Shen
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory and Stanford University, Menlo Park, CA 94025, USA. .,Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics, Stanford University, Stanford, CA 94305, USA
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38
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Sprau PO, Kostin A, Kreisel A, Böhmer AE, Taufour V, Canfield PC, Mukherjee S, Hirschfeld PJ, Andersen BM, Davis JCS. Discovery of orbital-selective Cooper pairing in FeSe. Science 2018; 357:75-80. [PMID: 28684522 DOI: 10.1126/science.aal1575] [Citation(s) in RCA: 236] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 06/05/2017] [Indexed: 11/02/2022]
Abstract
The superconductor iron selenide (FeSe) is of intense interest owing to its unusual nonmagnetic nematic state and potential for high-temperature superconductivity. But its Cooper pairing mechanism has not been determined. We used Bogoliubov quasiparticle interference imaging to determine the Fermi surface geometry of the electronic bands surrounding the Γ = (0, 0) and X = (π/aFe, 0) points of FeSe and to measure the corresponding superconducting energy gaps. We show that both gaps are extremely anisotropic but nodeless and that they exhibit gap maxima oriented orthogonally in momentum space. Moreover, by implementing a novel technique, we demonstrate that these gaps have opposite sign with respect to each other. This complex gap configuration reveals the existence of orbital-selective Cooper pairing that, in FeSe, is based preferentially on electrons from the d yz orbitals of the iron atoms.
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Affiliation(s)
- P O Sprau
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA.,Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - A Kostin
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA.,Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - A Kreisel
- Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK 2100 Copenhagen, Denmark.,Institut für Theoretische Physik, Universität Leipzig, D-04103 Leipzig, Germany
| | - A E Böhmer
- Ames Laboratory, U.S. Department of Energy, Ames, IA 50011, USA
| | - V Taufour
- Ames Laboratory, U.S. Department of Energy, Ames, IA 50011, USA
| | - P C Canfield
- Ames Laboratory, U.S. Department of Energy, Ames, IA 50011, USA.,Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA
| | - S Mukherjee
- Department of Physics, Binghamton University-State University of New York, Binghamton, NY, USA
| | - P J Hirschfeld
- Department of Physics, University of Florida, Gainesville, FL 32611, USA
| | - B M Andersen
- Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK 2100 Copenhagen, Denmark
| | - J C Séamus Davis
- Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, NY 14853, USA. .,Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA.,School of Physics and Astronomy, University of St Andrews, Fife KY16 9SS, Scotland.,Tyndall National Institute, University College Cork, Cork T12R5C, Ireland
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39
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Pan B, Shen Y, Hu D, Feng Y, Park JT, Christianson AD, Wang Q, Hao Y, Wo H, Yin Z, Maier TA, Zhao J. Structure of spin excitations in heavily electron-doped Li 0.8Fe 0.2ODFeSe superconductors. Nat Commun 2017; 8:123. [PMID: 28743902 PMCID: PMC5527112 DOI: 10.1038/s41467-017-00162-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 06/07/2017] [Indexed: 11/26/2022] Open
Abstract
Heavily electron-doped iron-selenide high-transition-temperature (high-Tc) superconductors, which have no hole Fermi pockets, but have a notably high Tc, have challenged the prevailing s± pairing scenario originally proposed for iron pnictides containing both electron and hole pockets. The microscopic mechanism underlying the enhanced superconductivity in heavily electron-doped iron-selenide remains unclear. Here, we used neutron scattering to study the spin excitations of the heavily electron-doped iron-selenide material Li0.8Fe0.2ODFeSe (Tc = 41 K). Our data revealed nearly ring-shaped magnetic resonant excitations surrounding (π, π) at ∼21 meV. As the energy increased, the spin excitations assumed a diamond shape, and they dispersed outward until the energy reached ∼60 meV and then inward at higher energies. The observed energy-dependent momentum structure and twisted dispersion of spin excitations near (π, π) are analogous to those of hole-doped cuprates in several aspects, thus implying that such spin excitations are essential for the remarkably high Tc in these materials. The microscopic mechanism underlying an enhanced superconductivity in electron-doped iron selenide superconductor remains unclear. Here, Pan et al. report the spin excitations of Li0.8Fe0.2ODFeSe, revealing analogous momentum structure and dispersion to hole-doped cuprates.
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Affiliation(s)
- Bingying Pan
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Yao Shen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Die Hu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Yu Feng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - J T Park
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Garching, D-85748, Germany
| | - A D Christianson
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831-6393, USA.,Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - Qisi Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Yiqing Hao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Hongliang Wo
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Zhiping Yin
- Department of Physics and Center for Advanced Quantum Studies, Beijing Normal University, Beijing, 100875, China
| | - T A Maier
- Computer Science and Mathematics Division and Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA.,Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - Jun Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China. .,Collaborative Innovation Center of Advanced Microstructures, Nanjing, 210093, China.
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40
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Lai HH, Hu WJ, Nica EM, Yu R, Si Q. Antiferroquadrupolar Order and Rotational Symmetry Breaking in a Generalized Bilinear-Biquadratic Model on a Square Lattice. PHYSICAL REVIEW LETTERS 2017; 118:176401. [PMID: 28498700 DOI: 10.1103/physrevlett.118.176401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Indexed: 06/07/2023]
Abstract
The magnetic and nematic properties of the iron chalcogenides have recently been the subject of intense interest. Motivated by the proposed antiferroquadrupolar and Ising-nematic orders for the bulk FeSe, we study the phase diagram of an S=1 generalized bilinear-biquadratic model with multineighbor interactions. We find a large parameter regime for a (π, 0) antiferroquadrupolar phase, showing how quantum fluctuations stabilize it by lifting an infinite degeneracy of certain semiclassical states. Evidence for this C_{4}-symmetry-breaking quadrupolar phase is also provided by an unbiased density matrix renormalization group analysis. We discuss the implications of our results for FeSe and related iron-based superconductors.
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Affiliation(s)
- Hsin-Hua Lai
- Department of Physics and Astronomy & Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Wen-Jun Hu
- Department of Physics and Astronomy & Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Emilian M Nica
- Department of Physics and Astronomy & Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Rong Yu
- Department of Physics, Renmin University of China, Beijing 100872, China
- Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China and Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Qimiao Si
- Department of Physics and Astronomy & Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
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41
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Zhang W, Park JT, Lu X, Wei Y, Ma X, Hao L, Dai P, Meng ZY, Yang YF, Luo H, Li S. Effect of Nematic Order on the Low-Energy Spin Fluctuations in Detwinned BaFe_{1.935}Ni_{0.065}As_{2}. PHYSICAL REVIEW LETTERS 2016; 117:227003. [PMID: 27925732 DOI: 10.1103/physrevlett.117.227003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Indexed: 06/06/2023]
Abstract
The origin of nematic order remains one of the major debates in iron-based superconductors. In theories based on spin nematicity, one major prediction is that the spin-spin correlation length at (0,π) should decrease with decreasing temperature below the structural transition temperature T_{s}. Here, we report inelastic neutron scattering studies on the low-energy spin fluctuations in BaFe_{1.935}Ni_{0.065}As_{2} under uniaxial pressure. Both intensity and spin-spin correlation start to show anisotropic behavior at high temperature, while the reduction of the spin-spin correlation length at (0,π) happens just below T_{s}, suggesting the strong effect of nematic order on low-energy spin fluctuations. Our results favor the idea that treats the spin degree of freedom as the driving force of the electronic nematic order.
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Affiliation(s)
- Wenliang Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - J T Park
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, D-85748 Garching, Germany
| | - Xingye Lu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yuan Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaoyan Ma
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Lijie Hao
- China Institute of Atomic Energy, Beijing 102413, China
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005-1827, USA
| | - Zi Yang Meng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yi-Feng Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Huiqian Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Shiliang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
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42
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Xu HC, Niu XH, Xu DF, Jiang J, Yao Q, Chen QY, Song Q, Abdel-Hafiez M, Chareev DA, Vasiliev AN, Wang QS, Wo HL, Zhao J, Peng R, Feng DL. Highly Anisotropic and Twofold Symmetric Superconducting Gap in Nematically Ordered FeSe_{0.93}S_{0.07}. PHYSICAL REVIEW LETTERS 2016; 117:157003. [PMID: 27768370 DOI: 10.1103/physrevlett.117.157003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Indexed: 06/06/2023]
Abstract
FeSe exhibits a novel ground state in which superconductivity coexists with a nematic order in the absence of any long-range magnetic order. Here, we report on an angle-resolved photoemission study on the superconducting gap structure in the nematic state of FeSe_{0.93}S_{0.07}, without the complications caused by Fermi surface reconstruction induced by magnetic order. We find that the superconducting gap shows a pronounced twofold anisotropy around the elliptical hole pocket near Z (0, 0, π), with gap minima at the end points of its major axis, while no detectable gap is observed around Γ (0, 0, 0) and the zone corner (π, π, k_{z}). The large anisotropy and nodal gap distribution demonstrate the substantial effects of the nematicity on the superconductivity and thus put strong constraints on current theories.
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Affiliation(s)
- H C Xu
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, People's Republic of China
| | - X H Niu
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, People's Republic of China
| | - D F Xu
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, People's Republic of China
| | - J Jiang
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, People's Republic of China
| | - Q Yao
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, People's Republic of China
| | - Q Y Chen
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, People's Republic of China
| | - Q Song
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, People's Republic of China
| | - M Abdel-Hafiez
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, China
- Faculty of science, Physics Department, Fayoum University, 63514 Fayoum, Egypt
| | - D A Chareev
- Institute of Experimental Mineralogy, Russian Academy of Sciences, 142432 Chernogolovka, Moscow District, Russia
- Institute of Physics and Technology, Ural Federal University, 620002 Ekaterinburg, Russia
| | - A N Vasiliev
- Institute of Physics and Technology, Ural Federal University, 620002 Ekaterinburg, Russia
- Low Temperature Physics and Superconductivity Department, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Q S Wang
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, People's Republic of China
| | - H L Wo
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, People's Republic of China
| | - J Zhao
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, People's Republic of China
| | - R Peng
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, People's Republic of China
| | - D L Feng
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, People's Republic of China
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Massat P, Farina D, Paul I, Karlsson S, Strobel P, Toulemonde P, Méasson MA, Cazayous M, Sacuto A, Kasahara S, Shibauchi T, Matsuda Y, Gallais Y. Charge-induced nematicity in FeSe. Proc Natl Acad Sci U S A 2016; 113:9177-81. [PMID: 27482118 PMCID: PMC4995930 DOI: 10.1073/pnas.1606562113] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The spontaneous appearance of nematicity, a state of matter that breaks rotation but not translation symmetry, is one of the most intriguing properties of the iron-based superconductors (Fe SC), and has relevance for the cuprates as well. Establishing the critical electronic modes behind nematicity remains a challenge, however, because their associated susceptibilities are not easily accessible by conventional probes. Here, using FeSe as a model system, and symmetry-resolved electronic Raman scattering as a probe, we unravel the presence of critical charge nematic fluctuations near the structural/nematic transition temperature, [Formula: see text] 90 K. The diverging behavior of the associated nematic susceptibility foretells the presence of a Pomeranchuk instability of the Fermi surface with d-wave symmetry. The excellent scaling between the observed nematic susceptibility and elastic modulus data demonstrates that the structural distortion is driven by this d-wave Pomeranchuk transition. Our results make a strong case for charge-induced nematicity in FeSe.
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Affiliation(s)
- Pierre Massat
- Laboratoire Matériaux et Phénomènes Quantiques, CNRS UMR7162, Université Paris Diderot, Paris Cedex 13, France
| | - Donato Farina
- Laboratoire Matériaux et Phénomènes Quantiques, CNRS UMR7162, Université Paris Diderot, Paris Cedex 13, France
| | - Indranil Paul
- Laboratoire Matériaux et Phénomènes Quantiques, CNRS UMR7162, Université Paris Diderot, Paris Cedex 13, France
| | - Sandra Karlsson
- Institut Néél, CNRS Unité Propre de Recherche 2940, 38042 Grenoble, France; Institut Néél, Université Grenoble Alpes, 38042 Grenoble, France
| | - Pierre Strobel
- Institut Néél, CNRS Unité Propre de Recherche 2940, 38042 Grenoble, France; Institut Néél, Université Grenoble Alpes, 38042 Grenoble, France
| | - Pierre Toulemonde
- Institut Néél, CNRS Unité Propre de Recherche 2940, 38042 Grenoble, France; Institut Néél, Université Grenoble Alpes, 38042 Grenoble, France
| | - Marie-Aude Méasson
- Laboratoire Matériaux et Phénomènes Quantiques, CNRS UMR7162, Université Paris Diderot, Paris Cedex 13, France
| | - Maximilien Cazayous
- Laboratoire Matériaux et Phénomènes Quantiques, CNRS UMR7162, Université Paris Diderot, Paris Cedex 13, France
| | - Alain Sacuto
- Laboratoire Matériaux et Phénomènes Quantiques, CNRS UMR7162, Université Paris Diderot, Paris Cedex 13, France
| | | | - Takasada Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Yuji Matsuda
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Yann Gallais
- Laboratoire Matériaux et Phénomènes Quantiques, CNRS UMR7162, Université Paris Diderot, Paris Cedex 13, France;
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44
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Abstract
Elucidating the nature of the magnetism of a high-temperature superconductor is crucial for establishing its pairing mechanism. The parent compounds of the cuprate and iron-pnictide superconductors exhibit Néel and stripe magnetic order, respectively. However, FeSe, the structurally simplest iron-based superconductor, shows nematic order (Ts=90 K), but not magnetic order in the parent phase, and its magnetic ground state is intensely debated. Here we report inelastic neutron-scattering experiments that reveal both stripe and Néel spin fluctuations over a wide energy range at 110 K. On entering the nematic phase, a substantial amount of spectral weight is transferred from the Néel to the stripe spin fluctuations. Moreover, the total fluctuating magnetic moment of FeSe is ∼60% larger than that in the iron pnictide BaFe2As2. Our results suggest that FeSe is a novel S=1 nematic quantum-disordered paramagnet interpolating between the Néel and stripe magnetic instabilities. Different ground states of high-temperature superconductors reveal complex nature of magnetism. Here, Wang et al. report stripe and Néel spin fluctuations coexisting with non-magnetic nematic phase in FeSe, providing a viewpoint towards understanding the magnetism of cuprate and iron-based superconductors.
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45
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Sun JP, Matsuura K, Ye GZ, Mizukami Y, Shimozawa M, Matsubayashi K, Yamashita M, Watashige T, Kasahara S, Matsuda Y, Yan JQ, Sales BC, Uwatoko Y, Cheng JG, Shibauchi T. Dome-shaped magnetic order competing with high-temperature superconductivity at high pressures in FeSe. Nat Commun 2016; 7:12146. [PMID: 27431724 PMCID: PMC4960320 DOI: 10.1038/ncomms12146] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 06/05/2016] [Indexed: 11/24/2022] Open
Abstract
The coexistence and competition between superconductivity and electronic orders, such as spin or charge density waves, have been a central issue in high transition-temperature (Tc) superconductors. Unlike other iron-based superconductors, FeSe exhibits nematic ordering without magnetism whose relationship with its superconductivity remains unclear. Moreover, a pressure-induced fourfold increase of Tc has been reported, which poses a profound mystery. Here we report high-pressure magnetotransport measurements in FeSe up to ∼15 GPa, which uncover the dome shape of magnetic phase superseding the nematic order. Above ∼6 GPa the sudden enhancement of superconductivity (Tc≤38.3 K) accompanies a suppression of magnetic order, demonstrating their competing nature with very similar energy scales. Above the magnetic dome, we find anomalous transport properties suggesting a possible pseudogap formation, whereas linear-in-temperature resistivity is observed in the normal states of the high-Tc phase above 6 GPa. The obtained phase diagram highlights unique features of FeSe among iron-based superconductors, but bears some resemblance to that of high-Tc cuprates.
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Affiliation(s)
- J. P. Sun
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - K. Matsuura
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - G. Z. Ye
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Science and Technology, Yunnan University, Kunming 650091, China
| | - Y. Mizukami
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - M. Shimozawa
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - K. Matsubayashi
- Department of Engineering Science, The University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - M. Yamashita
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - T. Watashige
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - S. Kasahara
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Y. Matsuda
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - J. -Q. Yan
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - B. C. Sales
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Y. Uwatoko
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - J. -G. Cheng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - T. Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
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46
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47
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Band structure reconstruction across nematic order in high quality FeSe single crystal as revealed by optical spectroscopy study. Sci Bull (Beijing) 2016. [DOI: 10.1007/s11434-016-1102-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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48
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Wang Z, Hu WJ, Nevidomskyy AH. Spin Ferroquadrupolar Order in the Nematic Phase of FeSe. PHYSICAL REVIEW LETTERS 2016; 116:247203. [PMID: 27367404 DOI: 10.1103/physrevlett.116.247203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Indexed: 06/06/2023]
Abstract
We provide evidence that spin ferroquadrupolar (FQ) order is the likely ground state in the nonmagnetic nematic phase of stoichiometric FeSe. By studying the variational mean-field phase diagram of a bilinear-biquadratic Heisenberg model up to the 2nd nearest neighbor, we find the FQ phase in close proximity to the columnar antiferromagnet commonly realized in iron-based superconductors; the stability of the FQ phase is further verified by the density matrix renormalization group. The dynamical spin structure factor in the FQ state is calculated with flavor-wave theory, which yields a qualitatively consistent result with inelastic neutron scattering experiments on FeSe at both low and high energies. We verify that FQ can coexist with C_{4} breaking environments in the mean-field calculation, and further discuss the possibility that quantum fluctuations in FQ act as a source of nematicity.
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Affiliation(s)
- Zhentao Wang
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Wen-Jun Hu
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
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49
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Onari S, Yamakawa Y, Kontani H. Sign-Reversing Orbital Polarization in the Nematic Phase of FeSe due to the C_{2} Symmetry Breaking in the Self-Energy. PHYSICAL REVIEW LETTERS 2016; 116:227001. [PMID: 27314734 DOI: 10.1103/physrevlett.116.227001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Indexed: 06/06/2023]
Abstract
To understand the nematicity in Fe-based superconductors, nontrivial k dependence of the orbital polarization [ΔE_{xz}(k), ΔE_{yz}(k)] in the nematic phase, such as the sign reversal of the orbital splitting between Γ and X, Y points in FeSe, provides significant information. To solve this problem, we study the spontaneous symmetry breaking with respect to the orbital polarization and spin susceptibility self-consistently. In FeSe, due to the sign-reversing orbital order, the hole and electron pockets are elongated along the k_{y} and k_{x} axes, respectively, consistently with experiments. In addition, an electron pocket splits into two Dirac cone Fermi pockets while increasing the orbital polarization. The orbital order in Fe-based superconductors originates from the strong positive feedback between the nematic orbital order and spin susceptibility.
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Affiliation(s)
- Seiichiro Onari
- Department of Physics, Okayama University, Okayama 700-8530, Japan
- Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
| | - Youichi Yamakawa
- Department of Physics, Nagoya University, Furo-cho, Nagoya 464-8602, Japan
| | - Hiroshi Kontani
- Department of Physics, Nagoya University, Furo-cho, Nagoya 464-8602, Japan
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50
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Tian YC, Zhang WH, Li FS, Wu YL, Wu Q, Sun F, Zhou GY, Wang L, Ma X, Xue QK, Zhao J. Ultrafast Dynamics Evidence of High Temperature Superconductivity in Single Unit Cell FeSe on SrTiO_{3}. PHYSICAL REVIEW LETTERS 2016; 116:107001. [PMID: 27015504 DOI: 10.1103/physrevlett.116.107001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Indexed: 06/05/2023]
Abstract
We report the time-resolved excited state ultrafast dynamics of single unit cell (1 UC) thick FeSe films on SrTiO_{3} (STO), with FeTe capping layers. By measuring the photoexcited quasiparticles' density and lifetime, we unambiguously identify a superconducting (SC) phase transition, with a transition temperature T_{c} of 68 (-5/+2) K and a SC gap of Δ(0)=20.2±1.5 meV. The obtained electron-phonon coupling strength λ is as large as 0.48, demonstrating the likely crucial role of electron-phonon coupling in the high temperature superconductivity of the 1 UC FeSe on STO systems. We further find a 0.05 THz coherent acoustic phonon branch in the capping layer, which provides an additional decay channel to the gluing bosons.
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Affiliation(s)
- Y C Tian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - W H Zhang
- State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
| | - F S Li
- State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Y L Wu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Q Wu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - F Sun
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - G Y Zhou
- State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Lili Wang
- State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Xucun Ma
- State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Qi-Kun Xue
- State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Jimin Zhao
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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