1
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Guo N, Chen X, Yu T, Fan Y, Zhang Q, Lei M, Xu X, Zhu X, Guo J, Gu L, Xu H, Peng R, Feng D. Inferior Interfacial Superconductivity in 1 UC FeSe/SrVO 3/SrTiO 3 with Screened Interfacial Electron-Phonon Coupling. NANO LETTERS 2024; 24:8587-8594. [PMID: 38967395 DOI: 10.1021/acs.nanolett.4c01612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/06/2024]
Abstract
Single-unit cell (1 UC) FeSe interfaced with TiOx or FeOx exhibits significantly enhanced superconductivity compared to that of bulk FeSe, with interfacial electron-phonon coupling (EPC) playing a crucial role. However, the reduced dimensionality in 1 UC FeSe, which may drive superconducting fluctuations, complicates our understanding of the enhancement mechanisms. We construct a new superconducting interface, 1 UC FeSe/SrVO3/SrTiO3. Here, the itinerant electrons of highly metallic SrVO3 films can screen all high-energy Fuchs-Kliewer phonons, including those of SrTiO3, making it the first FeSe/oxide system with screened interfacial EPC while maintaining the 1 UC FeSe thickness. Despite comparable doping levels, the heavily electron-doped 1 UC FeSe/SrVO3 exhibits a pairing temperature (Tg ∼ 48 K) lower than those of FeSe/SrTiO3 and FeSe/LaFeO3. Our findings disentangle the contributions of interfacial EPC from dimensionality in terms of enhancing Tg in FeSe/oxide interfaces, underscoring the critical importance of interfacial EPC. This FeSe/VOx interface also provides a platform for studying interfacial superconductivity.
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Affiliation(s)
- Nan Guo
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Xiaoyang Chen
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Tianlun Yu
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yu Fan
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Minyinan Lei
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
| | - Xiaofeng Xu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xuetao Zhu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Jiandong Guo
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Haichao Xu
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Rui Peng
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Donglai Feng
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, 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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Qiao J, Ran H, Zhou Q, Qiao R, Lyu Z, Gao X, Liu Y, Yan J, Chen P. Gram-Scale Synthesis of Black Phosphorus through Shock-Induced Phase Transformation. Inorg Chem 2024; 63:5378-5388. [PMID: 38481134 DOI: 10.1021/acs.inorgchem.3c03965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
This article presents the utilization of a cylindrical double-tube shock loading device in conjunction with amorphous red phosphorus as the precursor to investigate the complete phase transformation of red phosphorus into black phosphorus under the influence of shockwaves. Multiple experiments were conducted by varying the shock pressure and temperature parameters. The characterization of the recovered samples involved analysis of the phase composition and microstructure. The obtained experimental results demonstrate that within the cylindrical double-tube shock loading setup, a pressure of 9 GPa and a temperature of 800 K are optimal for achieving the complete phase transition of amorphous red phosphorus into orthorhombic black phosphorus. By precisely controlling these experimental conditions, a high-quality orthorhombic black phosphorus powder with excellent crystallinity was successfully prepared. This method offers several advantages, including simplicity, cost-effectiveness, and high yield. Consequently, this presents a promising pathway for the industrial-scale production of black phosphorus. The implementation of this approach not only reduces the cost involved in black phosphorus synthesis but also contributes to the broad range of applications for this material.
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Affiliation(s)
- Jinchao Qiao
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, 100081 Beijing, China
| | - Haotian Ran
- Chongqing Hongyu Precision Industrial Co LTD., 402760 Chongqing, China
| | - Qiang Zhou
- China Research and Development, Academy of Machinery Equipment, 100089 Beijing, China
| | - Rufei Qiao
- Army Infantry Academy, 330103 Nanchang, China
| | - Zhuwen Lyu
- Ningbo Branch, Ordnance Science Institute of China, 315103 Ningbo, China
| | - Xin Gao
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, 100081 Beijing, China
| | - Yan Liu
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, 100081 Beijing, China
| | - Junbo Yan
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, 100081 Beijing, China
| | - Pengwan Chen
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, 100081 Beijing, China
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3
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Xue CL, Dou LG, Xu YJ, Yuan QQ, Li QY, Jia ZY, Li Z, Liu R, Li SC. Iron Vacancy Tunable Superconductor-Insulator Transition in FeSe/SrTiO_{3} Monolayer. PHYSICAL REVIEW LETTERS 2023; 131:256002. [PMID: 38181352 DOI: 10.1103/physrevlett.131.256002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 11/15/2023] [Accepted: 11/21/2023] [Indexed: 01/07/2024]
Abstract
The Fe_{4}Se_{5} with a sqrt[5]×sqrt[5] Fe vacancy order is suggested to be a Mott insulator and the parent state of bulk FeSe superconductor. The iron vacancy ordered state has been considered as a Mott insulator and the parent compound of bulk FeSe-based superconductors. However, for the superconducting FeSe/SrTiO_{3} monolayer (FeSe/STO) with an interface-enhanced high transition temperature (T_{c}), the electronic evolution from its Fe vacancy ordered parent phase to the superconducting state, has not been explored due to the challenge to realize an Fe vacancy order in the FeSe/STO monolayer, even though important to the understanding of superconductivity mechanism. In this study, we developed a new method to generate Fe vacancies within the FeSe/STO monolayer in a tunable fashion, with the assistance of atomic hydrogen. As a consequence, an insulating sqrt[5]×sqrt[5] Fe vacancy ordered monolayer is realized as the parent state. By using scanning tunneling microscopy and scanning tunneling spectroscopy, the spectral evolution from superconductivity to insulator is fully characterized. Surprisingly, a prominent spectral weight transfer occurs, thus implying a strong electron correlation effect. Moreover, the Fe vacancy induced insulating gap exhibits no Mott gap-like features. This work provides new insights in understanding the high-T_{c} superconductivity in FeSe/STO monolayer.
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Affiliation(s)
- Cheng-Long Xue
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Li-Guo Dou
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Yong-Jie Xu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Qian-Qian Yuan
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Qi-Yuan Li
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Zhen-Yu Jia
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Zishuang Li
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Ronghua Liu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Jiangsu Provincial Key Laboratory for Nanotechnology, Nanjing University, Nanjing 210093, China
| | - Shao-Chun Li
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Jiangsu Provincial Key Laboratory for Nanotechnology, Nanjing University, Nanjing 210093, China
- Hefei National Laboratory, Hefei 230088, China
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4
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Zhang W, Zhang ZM, Nie JH, Gong BC, Cai M, Liu K, Lu ZY, Fu YS. Spin-Resolved Imaging of Antiferromagnetic Order in Fe 4 Se 5 Ultrathin Films on SrTiO 3. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209931. [PMID: 36790865 DOI: 10.1002/adma.202209931] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 01/17/2023] [Indexed: 05/12/2023]
Abstract
Unraveling the magnetic order in iron chalcogenides and pnictides at atomic scale is pivotal for understanding their unconventional superconducting pairing mechanism, but is experimentally challenging. Here, by utilizing spin-polarized scanning tunneling microscopy, real-space spin contrasts are successfully resolved to exhibit atomically unidirectional stripes in Fe4 Se5 ultrathin films, the plausible closely related compound of bulk FeSe with ordered Fe-vacancies, which are grown by molecular beam epitaxy. As is substantiated by the first-principles electronic structure calculations, the spin contrast originates from a pair-checkerboard antiferromagnetic ground state with in-plane magnetization, which is modulated by a spin-lattice coupling. These measurements further identify three types of nanoscale antiferromagnetic domains with distinguishable spin contrasts, which are subject to thermal fluctuations into short-ranged patches at elevated temperatures. This work provides promising opportunities in understanding the emergent magnetic order and the electronic phase diagram for FeSe-derived superconductors.
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Affiliation(s)
- Wenhao Zhang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Zhi-Mo Zhang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Jin-Hua Nie
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Ben-Chao Gong
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing, 100872, China
| | - Min Cai
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Kai Liu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing, 100872, China
| | - Zhong-Yi Lu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing, 100872, China
| | - Ying-Shuang Fu
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China
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5
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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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6
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Zhang ZM, Gong BC, Nie JH, Meng F, Zhang Q, Gu L, Liu K, Lu ZY, Fu YS, Zhang W. Self-Intercalated 1T-FeSe 2 as an Effective Kagome Lattice. NANO LETTERS 2023; 23:954-961. [PMID: 36706049 DOI: 10.1021/acs.nanolett.2c04362] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
In kagome lattice, with the emergence of Dirac cones and flat band in electronic structure, it provides a versatile ground for exploring intriguing interplay among frustrated geometry, topology and correlation. However, such engaging interest is strongly limited by available kagome materials in nature. Here we report on a synthetic strategy of constructing kagome systems via self-intercalation of Fe atoms into the van der Waals gap of FeSe2 via molecular beam epitaxy. Using low-temperature scanning tunneling microscopy, we unveil a kagome-like morphology upon intercalating a 2 × 2 ordered Fe atoms, resulting in a stoichiometry of Fe5Se8. Both the bias-dependent STM imaging and theoretical modeling calculations suggest that the kagome pattern mainly originates from slight but important reconstruction of topmost Se atoms, incurred by the nonequivalent subsurface Fe sites due to the intercalation. Our study demonstrates an alternative approach of constructing artificial kagome structures, which envisions to be tuned for exploring correlated quantum states.
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Affiliation(s)
- Zhi-Mo Zhang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan430074, China
| | - Ben-Chao Gong
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing100872, China
| | - Jin-Hua Nie
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan430074, China
| | - Fanqi Meng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing100190, P.R. China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing100190, P.R. China
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing100190, P.R. China
| | - Kai Liu
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing100872, China
| | - Zhong-Yi Lu
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing100872, China
| | - Ying-Shuang Fu
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan430074, China
| | - Wenhao Zhang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan430074, China
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7
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Stoichiometric Growth of Monolayer FeSe Superconducting Films Using a Selenium Cracking Source. CRYSTALS 2022. [DOI: 10.3390/cryst12060853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
As a novel interfacial high-temperature superconductor, monolayer FeSe on SrTiO3 has been intensely studied in the past decade. The high selenium flux involved in the traditional growth method complicates the film’s composition and entails more sample processing to realize the superconductivity. Here we use a Se cracking source for the molecular beam epitaxy growth of FeSe films to boost the reactivity of the Se flux. Reflection high-energy electron diffraction shows that the growth rate of FeSe increases with the increasing Se flux when the Fe flux is fixed, indicating that the Se over-flux induces Fe vacancies. Through careful tuning, we find that the proper Se/Fe flux ratio with Se cracked that is required for growing stoichiometric FeSe is close to 1, much lower than that with the uncracked Se flux. Furthermore, the FeSe film produced by the optimized conditions shows high-temperature superconductivity in the transport measurements without any post-growth treatment. Our work reinforces the importance of stoichiometry for superconductivity and establishes a simpler and more efficient approach to fabricating monolayer FeSe superconducting films.
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8
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Xie J, Liu X, Zhang W, Wong SM, Zhou X, Zhao Y, Wang S, Lai KT, Goh SK. Fragile Pressure-Induced Magnetism in FeSe Superconductors with a Thickness Reduction. NANO LETTERS 2021; 21:9310-9317. [PMID: 34714653 DOI: 10.1021/acs.nanolett.1c03508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The emergence of high transition temperature (Tc) superconductivity in bulk FeSe under pressure is associated with the tuning of nematicity and magnetism. However, sorting out the relative contributions from magnetic and nematic fluctuations to the enhancement of Tc remains challenging. Here, we design and conduct a series of high-pressure experiments on FeSe thin flakes. We find that as the thickness decreases the nematic phase boundary on temperature-pressure phase diagrams remains robust while the magnetic order is significantly weakened. A local maximum of Tc is observed outside the nematic phase region, not far from the extrapolated nematic end point in all samples. However, the maximum Tc value is reduced associated with the weakening of magnetism. No high-Tc phase is observed in the thinnest sample. Our results strongly suggest that nematic fluctuations alone can only have a limited effect while magnetic fluctuations are pivotal on the enhancement of Tc in FeSe.
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Affiliation(s)
- Jianyu Xie
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Xinyou Liu
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Wei Zhang
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Sum Ming Wong
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Xuefeng Zhou
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Yusheng Zhao
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Shanmin Wang
- Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Kwing To Lai
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Swee K Goh
- Department of Physics, The Chinese University of Hong Kong, Hong Kong SAR, China
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9
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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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10
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Ge Z, Zou Q, Zhang H, Yan C, Agterberg D, Weinert M, Li L. Superconductivity on Edge: Evidence of a One-Dimensional Superconducting Channel at the Edges of Single-Layer FeTeSe Antiferromagnetic Nanoribbons. ACS NANO 2020; 14:6539-6547. [PMID: 32363855 DOI: 10.1021/acsnano.9b08726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
How superconductivity emerges from antiferromagnetic ordering is an essential question for Fe-based superconductors. Here, we explore the effect of dimensionality on the interplay between antiferromagnetic ordering and superconductivity by investigating nanoribbons of single-layer FeTe1-xSex films grown on SrTiO3(001) substrates by molecular beam epitaxy. Using scanning tunneling microscopy/spectroscopy, we find a one-dimensional (1D) superconducting channel 2 nm wide with a TC of 42 ± 4 K on the edge of FeTe1-xSex (x < 0.1) ribbons, coexisting with a non-superconducting ribbon interior that remains bicollinear antiferromagnetically ordered. Density functional theory calculations indicate that both Se and the presence of the edge destabilize the bicollinear antiferromagnetic magnetic order, resulting in a paramagnetic region near the edge with strong local checkerboard fluctuations that is conducive to superconductivity. Our results represent the highest TC achieved in 1D superconductors and demonstrate an effective route toward stabilizing superconductivity in Fe-based superconductors at reduced dimensions.
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Affiliation(s)
- Zhuozhi Ge
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Qiang Zou
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Huimin Zhang
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Chenhui Yan
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Daniel Agterberg
- Department of Physics, University of Wisconsin, Milwaukee, Wisconsin 53211, United States
| | - Michael Weinert
- Department of Physics, University of Wisconsin, Milwaukee, Wisconsin 53211, United States
| | - Lian Li
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, United States
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11
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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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12
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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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13
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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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14
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Chareev D, Ovchenkov Y, Shvanskaya L, Kovalskii A, Abdel-Hafiez M, Trainer DJ, Lechner EM, Iavarone M, Volkova O, Vasiliev A. Single crystal growth, transport and scanning tunneling microscopy and spectroscopy of FeSe1−xSx. CrystEngComm 2018. [DOI: 10.1039/c8ce00074c] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
“Ampoule in ampoule” design to grow single crystals of FeSe1−xSx.
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Affiliation(s)
- Dmitriy Chareev
- RAS
- Institute of Experimental Mineralogy
- Chernogolovka 123456
- Russia
- Ural Federal University
| | | | - Larisa Shvanskaya
- Lomonosov Moscow State University
- Moscow 119991
- Russia
- National University of Science and Technology “MISiS”
- Moscow 119049
| | - Andrey Kovalskii
- National University of Science and Technology “MISiS”
- Moscow 119049
- Russia
| | - Mahmoud Abdel-Hafiez
- National University of Science and Technology “MISiS”
- Moscow 119049
- Russia
- Goethe University Frankfurt
- Frankfurt am Main 60438
| | | | | | | | - Olga Volkova
- Ural Federal University
- Ekaterinburg 620002
- Russia
- Lomonosov Moscow State University
- Moscow 119991
| | - Alexander Vasiliev
- Lomonosov Moscow State University
- Moscow 119991
- Russia
- National University of Science and Technology “MISiS”
- Moscow 119049
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15
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Wang Z, Liu C, Liu Y, Wang J. High-temperature superconductivity in one-unit-cell FeSe films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:153001. [PMID: 28176680 DOI: 10.1088/1361-648x/aa5f26] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Since the dramatic enhancement of the superconducting transition temperature (T c) was reported in a one-unit-cell FeSe film grown on a SrTiO3 substrate (1-UC FeSe/STO) by molecular beam epitaxy (MBE), related research on this system has become a new frontier in condensed matter physics. In this paper, we present a brief review on this rapidly developing field, mainly focusing on the superconducting properties of 1-UC FeSe/STO. Experimental evidence for high-temperature superconductivity in 1-UC FeSe/STO, including direct evidence revealed by transport and diamagnetic measurements, as well as other evidence from scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES), are overviewed. The potential mechanisms of the enhanced superconductivity are also discussed. There are accumulating arguments to suggest that the strengthened Cooper pairing in 1-UC FeSe/STO originates from the interface effects, specifically the charge transfer and coupling to phonon modes in the TiO2 plane. The study of superconductivity in 1-UC FeSe/STO not only sheds new light on the mechanism of high-temperature superconductors with layered structures, but also provides an insight into the exploration of new superconductors by interface engineering.
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Affiliation(s)
- Ziqiao Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
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16
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Jiao L, Huang CL, Rößler S, Koz C, Rößler UK, Schwarz U, Wirth S. Superconducting gap structure of FeSe. Sci Rep 2017; 7:44024. [PMID: 28266654 PMCID: PMC5339780 DOI: 10.1038/srep44024] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 02/01/2017] [Indexed: 11/26/2022] Open
Abstract
The microscopic mechanism governing the zero-resistance flow of current in some iron-based, high-temperature superconducting materials is not well understood up to now. A central issue concerning the investigation of these materials is their superconducting gap symmetry and structure. Here we present a combined study of low-temperature specific heat and scanning tunnelling microscopy measurements on single crystalline FeSe. The results reveal the existence of at least two superconducting gaps which can be represented by a phenomenological two-band model. The analysis of the specific heat suggests significant anisotropy in the gap magnitude with deep gap minima. The tunneling spectra display an overall "U"-shaped gap close to the Fermi level away as well as on top of twin boundaries. These results are compatible with the anisotropic nodeless models describing superconductivity in FeSe.
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Affiliation(s)
- Lin Jiao
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Chien-Lung Huang
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Sahana Rößler
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Cevriye Koz
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | | | - Ulrich Schwarz
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Steffen Wirth
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
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