1
|
Sur S, Xu Y, Li S, Gong SS, Nevidomskyy AH. Field-Induced Non-BEC Transitions in Frustrated Magnets. Phys Rev Lett 2024; 132:066701. [PMID: 38394558 DOI: 10.1103/physrevlett.132.066701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 12/12/2023] [Accepted: 01/04/2024] [Indexed: 02/25/2024]
Abstract
Frustrated spin systems have traditionally proven challenging to understand, owing to a scarcity of controlled methods for their analyses. By contrast, under strong magnetic fields, certain aspects of spin systems admit simpler and universal description in terms of hardcore bosons. The bosonic formalism is anchored by the phenomenon of Bose-Einstein condensation (BEC), which has helped explain the behaviors of a wide range of magnetic compounds under applied magnetic fields. Here, we focus on the interplay between frustration and externally applied magnetic field to identify instances where the BEC paradigm is no longer applicable. As a representative example, we consider the antiferromagnetic J_{1}-J_{2}-J_{3} model on the square lattice in the presence of a uniform external magnetic field, and demonstrate that the frustration-driven suppression of the Néel order leads to a Lifshitz transition for the hardcore bosons. In the vicinity of the Lifshitz point, the physics becomes unmoored from the BEC paradigm, and the behavior of the system, both at and below the saturation field, is controlled by a Lifshitz multicritical point. We obtain the resultant universal scaling behaviors, and provide strong evidence for the existence of a frustration and magnetic-field driven correlated bosonic liquid state along the entire phase boundary separating the Néel phase from other magnetically ordered states.
Collapse
Affiliation(s)
- Shouvik Sur
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Yi Xu
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Shuyi Li
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Shou-Shu Gong
- School of Physical Sciences, Great Bay University, Dongguan 523000, China, and Great Bay Institute for Advanced Study, Dongguan 523000, China
| | | |
Collapse
|
2
|
Butcher MW, Tanatar MA, Nevidomskyy AH. Anisotropic Melting of Frustrated Ising Antiferromagnets. Phys Rev Lett 2023; 130:166701. [PMID: 37154645 DOI: 10.1103/physrevlett.130.166701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 05/23/2022] [Accepted: 03/02/2023] [Indexed: 05/10/2023]
Abstract
Magnetic frustrations and dimensionality play an important role in determining the nature of the magnetic long-range order and how it melts at temperatures above the ordering transition T_{N}. In this Letter, we use large-scale Monte Carlo simulations to study these phenomena in a class of frustrated Ising spin models in two spatial dimensions. We find that the melting of the magnetic long-range order into an isotropic gaslike paramagnet proceeds via an intermediate stage where the classical spins remain anisotropically correlated. This correlated paramagnet exists in a temperature range T_{N}<T<T^{*}, whose width increases as magnetic frustrations grow. This intermediate phase is typically characterized by short-range correlations; however, the two-dimensional nature of the model allows for an additional exotic feature-formation of an incommensurate liquidlike phase with algebraically decaying spin correlations. The two-stage melting of magnetic order is generic and pertinent to many frustrated quasi-2D magnets with large (essentially classical) spins.
Collapse
Affiliation(s)
- Matthew W Butcher
- Department of Physics and Astronomy, Rice University, Houston Texas 77005, USA
| | - Makariy A Tanatar
- Ames National Laboratory, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | | |
Collapse
|
3
|
Gao B, Chen T, Wu XC, Flynn M, Duan C, Chen L, Huang CL, Liebman J, Li S, Ye F, Stone MB, Podlesnyak A, Abernathy DL, Adroja DT, Duc Le M, Huang Q, Nevidomskyy AH, Morosan E, Balents L, Dai P. Diffusive excitonic bands from frustrated triangular sublattice in a singlet-ground-state system. Nat Commun 2023; 14:2051. [PMID: 37045810 PMCID: PMC10097669 DOI: 10.1038/s41467-023-37669-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 03/26/2023] [Indexed: 04/14/2023] Open
Abstract
Magnetic order in most materials occurs when magnetic ions with finite moments arrange in a particular pattern below the ordering temperature. Intriguingly, if the crystal electric field (CEF) effect results in a spin-singlet ground state, a magnetic order can still occur due to the exchange interactions between neighboring ions admixing the excited CEF levels. The magnetic excitations in such a state are spin excitons generally dispersionless in reciprocal space. Here we use neutron scattering to study stoichiometric Ni2Mo3O8, where Ni2+ ions form a bipartite honeycomb lattice comprised of two triangular lattices, with ions subject to the tetrahedral and octahedral crystalline environment, respectively. We find that in both types of ions, the CEF excitations have nonmagnetic singlet ground states, yet the material has magnetic order. Furthermore, CEF spin excitons from the tetrahedral sites form a dispersive diffusive pattern around the Brillouin zone boundary, likely due to spin entanglement and geometric frustrations.
Collapse
Affiliation(s)
- Bin Gao
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - Tong Chen
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Xiao-Chuan Wu
- Department of Physics, University of California, Santa Barbara, CA, 93106, USA
| | - Michael Flynn
- Department of Physics, University of California, Davis, CA, 95616, USA
- Department of Physics, Boston University, Boston, MA, 02215, USA
| | - Chunruo Duan
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - Lebing Chen
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - Chien-Lung Huang
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
- Department of Physics and Center for Quantum Frontiers of Research & Technology (QFort), National Cheng Kung University, 701, Tainan, Taiwan
| | - Jesse Liebman
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Shuyi Li
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - Feng Ye
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Matthew B Stone
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Andrey Podlesnyak
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Douglas L Abernathy
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Devashibhai T Adroja
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX, UK
| | - Manh Duc Le
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX, UK
| | - Qingzhen Huang
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | | | - Emilia Morosan
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - Leon Balents
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA, 93106, USA
- Canadian Institute for Advanced Research, Toronto, ON, Canada
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA.
| |
Collapse
|
4
|
Luo J, Li S, Ye Z, Xu R, Yan H, Zhang J, Ye G, Chen L, Hu D, Teng X, Smith WA, Yakobson BI, Dai P, Nevidomskyy AH, He R, Zhu H. Evidence for Topological Magnon-Phonon Hybridization in a 2D Antiferromagnet down to the Monolayer Limit. Nano Lett 2023; 23:2023-2030. [PMID: 36797055 DOI: 10.1021/acs.nanolett.3c00351] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Topological phonons and magnons potentially enable low-loss, quantum coherent, and chiral transport of information and energy at the atomic scale. Van der Waals magnetic materials are promising to realize such states due to their recently discovered strong interactions among the electronic, spin, and lattice degrees of freedom. Here, we report the first observation of coherent hybridization of magnons and phonons in monolayer antiferromagnet FePSe3 by cavity-enhanced magneto-Raman spectroscopy. The robust magnon-phonon cooperativity in the 2D limit occurs even in zero magnetic field, which enables nontrivial band inversion between longitudinal and transverse optical phonons caused by the strong coupling with magnons. The spin and lattice symmetry theoretically guarantee magnetic-field-controlled topological phase transition, verified by nonzero Chern numbers calculated from the coupled spin-lattice model. The 2D topological magnon-phonon hybridization potentially offers a new route toward quantum phononics and magnonics with an ultrasmall footprint.
Collapse
Affiliation(s)
- Jiaming Luo
- Department of Materials Science and Nano Engineering, Rice University, Houston, Texas 77005, United States
- Applied Physics Graduate Program, Rice University, Houston, Texas 77005, United States
| | - Shuyi Li
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
| | - Zhipeng Ye
- Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409, United States
| | - Rui Xu
- Department of Materials Science and Nano Engineering, Rice University, Houston, Texas 77005, United States
| | - Han Yan
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
| | - Junjie Zhang
- Department of Materials Science and Nano Engineering, Rice University, Houston, Texas 77005, United States
| | - Gaihua Ye
- Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409, United States
| | - Lebing Chen
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
| | - Ding Hu
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
| | - Xiaokun Teng
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
| | - William A Smith
- Department of Materials Science and Nano Engineering, Rice University, Houston, Texas 77005, United States
| | - Boris I Yakobson
- Department of Materials Science and Nano Engineering, Rice University, Houston, Texas 77005, United States
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
| | - Andriy H Nevidomskyy
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
| | - Rui He
- Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409, United States
| | - Hanyu Zhu
- Department of Materials Science and Nano Engineering, Rice University, Houston, Texas 77005, United States
| |
Collapse
|
5
|
Hu WJ, Zhang Y, Nevidomskyy AH, Dagotto E, Si Q, Lai HH. Fractionalized Excitations Revealed by Entanglement Entropy. Phys Rev Lett 2020; 124:237201. [PMID: 32603177 DOI: 10.1103/physrevlett.124.237201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 05/27/2020] [Indexed: 06/11/2023]
Abstract
Fractionalized excitations develop in many unusual many-body states such as quantum spin liquids, disordered phases that cannot be described using any local order parameter. Because these exotic excitations correspond to emergent degrees of freedom, how to probe them and establish their existence is a long-standing challenge. We present a general procedure to reveal the fractionalized excitations using real-space entanglement entropy in critical spin liquids that are particularly relevant to experiments. Moreover, we show how to use the entanglement entropy to construct the corresponding spinon Fermi surface. Our work defines a new pathway to establish and characterize exotic excitations in novel quantum phases of matter.
Collapse
Affiliation(s)
- Wen-Jun Hu
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Department of Physics and Astronomy & Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Yi Zhang
- International Center for Quantum Materials, Peking University, Beijing, 100871, China
| | - Andriy H Nevidomskyy
- Department of Physics and Astronomy & Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Elbio Dagotto
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Qimiao Si
- Department of Physics and Astronomy & Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Hsin-Hua Lai
- Department of Physics and Astronomy & Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| |
Collapse
|
6
|
Rai BK, H. Oswald IW, Ban W, Huang CL, Loganathan V, Hallas AM, Wilson MN, Luke GM, Harriger L, Huang Q, Li Y, Dzsaber S, Chan JY, Wang NL, Paschen S, Lynn JW, Nevidomskyy AH, Dai P, Si Q, Morosan E. Low-carrier density and fragile magnetism in a Kondo lattice system. Phys Rev B 2019; 99:10.1103/PhysRevB.99.085120. [PMID: 38487214 PMCID: PMC10938852 DOI: 10.1103/physrevb.99.085120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/17/2024]
Abstract
Kondo-based semimetals and semiconductors are of extensive current interest as a viable platform for strongly correlated states in the dilute carrier limit. It is thus important to explore the routes to understand such systems. One established pathway is through the Kondo effect in metallic nonmagnetic analogs, in the so called half-filling case of one conduction electron and one 4f electron per site. Here, we demonstrate that Kondo-based semimetals develop out of conduction electrons with a low-carrier density in the presence of an even number of rare-earth sites. We do so by studying the Kondo material Yb3Ir4Ge13 along with its closed-4f -shell counterpart, Lu3Ir4Ge13. Through magnetotransport, optical conductivity, and thermodynamic measurements, we establish that the correlated semimetallic state of Yb3Ir4Ge13 below its Kondo temperature originates from the Kondo effect of a low-carrier conduction-electron background. In addition, it displays fragile magnetism at very low temperatures, which in turn, can be tuned to a Griffiths-phase-like regime through Lu-for-Yb substitution. These findings are connected with recent theoretical studies in simplified models. Our results can pave the way to exploring strong correlation physics in a semimetallic environment.
Collapse
Affiliation(s)
- Binod K. Rai
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Iain W. H. Oswald
- Department of Chemistry, University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Wenjing Ban
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - C.-L. Huang
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - V. Loganathan
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - A. M. Hallas
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada L8S 4M1
| | - M. N. Wilson
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada L8S 4M1
| | - G. M. Luke
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada L8S 4M1
- Canadian Institute for Advanced Research, 661 University Ave, Suite 505, Toronto, Ontario, Canada M5G 1M1
- TRIUMF, 4004 Wesbrook Mall, Vancouver, B.C., Canada V6T 2A3
| | - L. Harriger
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Q. Huang
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Y. Li
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Sami Dzsaber
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria
| | - Julia Y. Chan
- Department of Chemistry, University of Texas at Dallas, Richardson, Texas 75080, USA
| | - N. L. Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Silke Paschen
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria
| | - J. W. Lynn
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Andriy H. Nevidomskyy
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Pengcheng Dai
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Q. Si
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - E. Morosan
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| |
Collapse
|
7
|
Wang W, Song Y, Cao C, Tseng KF, Keller T, Li Y, Harriger LW, Tian W, Chi S, Yu R, Nevidomskyy AH, Dai P. Local orthorhombic lattice distortions in the paramagnetic tetragonal phase of superconducting NaFe 1-xNi xAs. Nat Commun 2018; 9:3128. [PMID: 30087342 PMCID: PMC6081486 DOI: 10.1038/s41467-018-05529-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 07/13/2018] [Indexed: 11/08/2022] Open
Abstract
Understanding the interplay between nematicity, magnetism and superconductivity is pivotal for elucidating the physics of iron-based superconductors. Here we use neutron scattering to probe magnetic and nematic orders throughout the phase diagram of NaFe1-xNixAs, finding that while both static antiferromagnetic and nematic orders compete with superconductivity, the onset temperatures for these two orders remain well separated approaching the putative quantum critical points. We uncover local orthorhombic distortions that persist well above the tetragonal-to-orthorhombic structural transition temperature Ts in underdoped samples and extend well into the overdoped regime that exhibits neither magnetic nor structural phase transitions. These unexpected local orthorhombic distortions display Curie-Weiss temperature dependence and become suppressed below the superconducting transition temperature Tc, suggesting that they result from the large nematic susceptibility near optimal superconductivity. Our results account for observations of rotational symmetry breaking above Ts, and attest to the presence of significant nematic fluctuations near optimal superconductivity.
Collapse
Affiliation(s)
- Weiyi Wang
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - Yu Song
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - Chongde Cao
- Department of Applied Physics, Northwestern Polytechnical University, Xian, 710072, China.
| | - Kuo-Feng Tseng
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany
- Max Planck Society Outstation at the Forschungsneutronenquelle Heinz Maier-Leibnitz (MLZ), D-85747, Garching, Germany
| | - Thomas Keller
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany
- Max Planck Society Outstation at the Forschungsneutronenquelle Heinz Maier-Leibnitz (MLZ), D-85747, Garching, Germany
| | - Yu Li
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA
| | - L W Harriger
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Wei Tian
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Songxue Chi
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Rong Yu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, Beijing, 100872, China
| | | | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA.
| |
Collapse
|
8
|
Wang Z, Hu WJ, Nevidomskyy AH. Erratum: Spin Ferroquadrupolar Order in the Nematic Phase of FeSe [Phys. Rev. Lett. 116, 247203 (2016)]. Phys Rev Lett 2017; 118:099901. [PMID: 28306289 DOI: 10.1103/physrevlett.118.099901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Indexed: 06/06/2023]
Abstract
This corrects the article DOI: 10.1103/PhysRevLett.116.247203.
Collapse
|
9
|
Yu R, Nevidomskyy AH. Competing superconducting channels in iron pnictides from the strong coupling theory with biquadratic spin interactions. J Phys Condens Matter 2016; 28:495702. [PMID: 27736803 DOI: 10.1088/0953-8984/28/49/495702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We study the symmetry and strength of the superconducting pairing in a two-orbital [Formula: see text] model for iron pnictides using the slave boson strong coupling approach. We show that the nearest-neighbor biquadratic interaction [Formula: see text] strongly affects the superconducting pairing phase diagram by promoting the [Formula: see text] B 1g and the [Formula: see text] A 1g channels. The resulting phase diagram consists of several competing pairing channels, including the isotropic [Formula: see text] A 1g channel, an anisotropic [Formula: see text] B 1g channel, and two [Formula: see text] pairing channels. We have investigated the evolution of superconducting states with electron doping, and find that the biquadratic interaction plays a crucial role in stabilizing the [Formula: see text] and even pure d-wave pairing in the heavily electron- and hole-doped regimes. In addition, we identify a novel orbital-B 1g pairing channel, which has a s-wave form factor but a B 1g symmetry. This channel has a comparable pairing amplitude to the d-wave pairing, and may strongly influence the superconducting gap anisotropy of the system in the overdoped regime. These findings are crucial in understanding the doping evolution of the superconducting gap anisotropy observed by angle resolved photoemission spectroscopy in the iron pnictides and iron chalcogenides, including the heavily K-doped BaFe2As2 and K-doped FeSe films.
Collapse
Affiliation(s)
- Rong Yu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, People's Republic of China. Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China and Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, People's Republic of China
| | | |
Collapse
|
10
|
Matt CE, Xu N, Lv B, Ma J, Bisti F, Park J, Shang T, Cao C, Song Y, Nevidomskyy AH, Dai P, Patthey L, Plumb NC, Radovic M, Mesot J, Shi M. NaFe_{0.56}Cu_{0.44}As: A Pnictide Insulating Phase Induced by On-Site Coulomb Interaction. Phys Rev Lett 2016; 117:097001. [PMID: 27610876 DOI: 10.1103/physrevlett.117.097001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Indexed: 06/06/2023]
Abstract
In the studies of iron pnictides, a key question is whether their bad-metal state from which the superconductivity emerges lies in close proximity with a magnetically ordered insulating phase. Recently, it was found that at low temperatures, the heavily Cu-doped NaFe_{1-x}Cu_{x}As (x>0.3) iron pnictide is an insulator with long-range antiferromagnetic order, similar to the parent compound of cuprates but distinct from all other iron pnictides. Using angle-resolved photoemission spectroscopy, we determined the momentum-resolved electronic structure of NaFe_{1-x}Cu_{x}As (x=0.44) and identified that its ground state is a narrow-gap insulator. Combining the experimental results with density functional theory (DFT) and DFT+U calculations, our analysis reveals that the on-site Coulombic (Hubbard) and Hund's coupling energies play crucial roles in the formation of the band gap about the chemical potential. We propose that at finite temperatures, charge carriers are thermally excited from the Cu-As-like valence band into the conduction band, which is of Fe 3d-like character. With increasing temperature, the number of electrons in the conduction band becomes larger and the hopping energy between Fe sites increases, and finally the long-range antiferromagnetic order is destroyed at T>T_{N}. Our study provides a basis for investigating the evolution of the electronic structure of a Mott insulator transforming into a bad metallic phase and eventually forming a superconducting state in iron pnictides.
Collapse
Affiliation(s)
- C E Matt
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - N Xu
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-10 15 Lausanne, Switzerland
| | - Baiqing Lv
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Junzhang Ma
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - F Bisti
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - J Park
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - T Shang
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-10 15 Lausanne, Switzerland
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - Chongde Cao
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Department of Applied Physics, Northwestern Polytechnical University, Xian 710072, China
| | - Yu Song
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | | | - Pengcheng Dai
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - L Patthey
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Radovic
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - J Mesot
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-10 15 Lausanne, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| |
Collapse
|
11
|
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.
Collapse
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
| | | |
Collapse
|
12
|
Ishii T, Toda R, Hanaoka Y, Tokiwa Y, Shimozawa M, Kasahara Y, Endo R, Terashima T, Nevidomskyy AH, Shibauchi T, Matsuda Y. Tuning the Magnetic Quantum Criticality of Artificial Kondo Superlattices CeRhIn_{5}/YbRhIn_{5}. Phys Rev Lett 2016; 116:206401. [PMID: 27258878 DOI: 10.1103/physrevlett.116.206401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Indexed: 06/05/2023]
Abstract
The effects of reduced dimensions and the interfaces on antiferromagnetic quantum criticality are studied in epitaxial Kondo superlattices, with alternating n layers of heavy-fermion antiferromagnet CeRhIn_{5} and seven layers of normal metal YbRhIn_{5}. As n is reduced, the Kondo coherence temperature is suppressed due to the reduction of effective Kondo screening. The Néel temperature is gradually suppressed as n decreases and the quasiparticle mass is strongly enhanced, implying dimensional control toward a quantum critical point. Magnetotransport measurements reveal that a quantum critical point is reached for the n=3 superlattice by applying small magnetic fields. Remarkably, the anisotropy of the quantum critical field is opposite to the expectations from the magnetic susceptibility in bulk CeRhIn_{5}, suggesting that the Rashba spin-orbit interaction arising from the inversion symmetry breaking at the interface plays a key role for tuning the quantum criticality in the two-dimensional Kondo lattice.
Collapse
Affiliation(s)
- T Ishii
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - R Toda
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Y Hanaoka
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - Y Tokiwa
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
- Research Center for Low Temperature and Materials Science, Kyoto University, Kyoto 606-8501, Japan
| | - M Shimozawa
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Y Kasahara
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - R Endo
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - T Terashima
- Research Center for Low Temperature and Materials Science, Kyoto University, Kyoto 606-8501, Japan
| | - A H Nevidomskyy
- Department of Physics and Astronomy, Rice University, 6100 Main Street, Houston, Texas 77005, USA
| | - T Shibauchi
- Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan
| | - Y Matsuda
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| |
Collapse
|
13
|
Wang Z, Kamiya Y, Nevidomskyy AH, Batista CD. Three-Dimensional Crystallization of Vortex Strings in Frustrated Quantum Magnets. Phys Rev Lett 2015; 115:107201. [PMID: 26382699 DOI: 10.1103/physrevlett.115.107201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Indexed: 06/05/2023]
Abstract
We demonstrate that frustrated exchange interactions can produce exotic 3D crystals of vortex strings near the saturation field (H=H(sat)) of body- and face-centered cubic Mott insulators. The combination of cubic symmetry and frustration leads to a magnon spectrum of the fully polarized spin state (H>H(sat)) with degenerate minima at multiple noncoplanar Q vectors. This spectrum becomes gapless at the quantum critical point H=H(sat) and the magnetic ordering below H(sat) can be formally described as a condensate of a dilute gas of bosons. By expanding in the lattice gas parameter, we find that different vortex crystals span sizable regions of the phase diagrams for isotropic exchange and are further stabilized by symmetric exchange anisotropy.
Collapse
Affiliation(s)
- Zhentao Wang
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - Yoshitomo Kamiya
- iTHES Research Group and Condensed Matter Theory Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | | | - Cristian D Batista
- Theoretical Division, T-4 and CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| |
Collapse
|
14
|
Abstract
Motivated by the recent angle-resolved photoemission spectroscopy (ARPES) on FeSe and iron pnictide families of iron-based superconductors, we have studied the orbital nematic order and its interplay with antiferromagnetism within the two-orbital Hubbard model. We used random phase approximation (RPA) to calculate the dependence of the orbital and magnetic susceptibilities on the strength of interactions and electron density (doping). To account for strong electron correlations not captured by RPA, we further employed non-perturbative variational cluster approximation (VCA) capable of capturing symmetry broken magnetic and orbitally ordered phases. Both approaches show that the electron and hole doping affect the two orders differently. While hole doping tends to suppress both magnetism and orbital ordering, the electron doping suppresses magnetism faster. Crucially, we find a realistic parameter regime for moderate electron doping that stabilizes orbital nematicity in the absence of long-range antiferromagnetic order. This is reminiscent of the non-magnetic orbital nematic phase observed recently in FeSe and a number of iron pnictide materials and raises the possibility that at least in some cases, the observed electronic nematicity may be primarily due to orbital rather than magnetic fluctuations.
Collapse
Affiliation(s)
- Zhentao Wang
- Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
| | | |
Collapse
|
15
|
Lin J, Ji H, Swift MW, Hardy WJ, Peng Z, Fan X, Nevidomskyy AH, Tour JM, Natelson D. Hydrogen diffusion and stabilization in single-crystal VO2 micro/nanobeams by direct atomic hydrogenation. Nano Lett 2014; 14:5445-5451. [PMID: 25148601 DOI: 10.1021/nl5030694] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report measurements of the diffusion of atomic hydrogen in single crystalline VO2 micro/nanobeams by direct exposure to atomic hydrogen, without catalyst. The atomic hydrogen is generated by a hot filament, and the doping process takes place at moderate temperature (373 K). Undoped VO2 has a metal-to-insulator phase transition at ∼340 K between a high-temperature, rutile, metallic phase and a low-temperature, monoclinic, insulating phase with a resistance exhibiting a semiconductor-like temperature dependence. Atomic hydrogenation results in stabilization of the metallic phase of VO2 micro/nanobeams down to 2 K, the lowest point we could reach in our measurement setup. Optical characterization shows that hydrogen atoms prefer to diffuse along the c axis of rutile (a axis of monoclinic) VO2, along the oxygen "channels". Based on observing the movement of the hydrogen diffusion front in single crystalline VO2 beams, we estimate the diffusion constant for hydrogen along the c axis of the rutile phase to be 6.7 × 10(-10) cm(2)/s at approximately 373 K, exceeding the value in isostructural TiO2 by ∼38×. Moreover, we find that the diffusion constant along the c axis of the rutile phase exceeds that along the equivalent a axis of the monoclinic phase by at least 3 orders of magnitude. This remarkable change in kinetics must originate from the distortion of the "channels" when the unit cell doubles along this direction upon cooling into the monoclinic structure. Ab initio calculation results are in good agreement with the experimental trends in the relative kinetics of the two phases. This raises the possibility of a switchable membrane for hydrogen transport.
Collapse
Affiliation(s)
- Jian Lin
- Department of Mechanical Engineering and Material Science, ‡Smalley Institute for Nanoscale Science and Technology, §Department of Physics and Astronomy, ⊥Department of Chemistry, ∥Department of Electrical and Computer Engineering, Rice University , 6100 Main Street, Houston, Texas 77005, United States
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Lu X, Park JT, Zhang R, Luo H, Nevidomskyy AH, Si Q, Dai P. Nematic spin correlations in the tetragonal state of uniaxial-strained BaFe
2−
x
Ni
x
As
2. Science 2014; 345:657-60. [DOI: 10.1126/science.1251853] [Citation(s) in RCA: 152] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Xingye Lu
- 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
| | - Rui Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, 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
| | | | - Qimiao Si
- Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
| | - Pengcheng Dai
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
| |
Collapse
|
17
|
Filinchuk Y, Tumanov NA, Ban V, Ji H, Wei J, Swift MW, Nevidomskyy AH, Natelson D. In Situ Diffraction Study of Catalytic Hydrogenation of VO2: Stable Phases and Origins of Metallicity. J Am Chem Soc 2014; 136:8100-9. [DOI: 10.1021/ja503360y] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yaroslav Filinchuk
- Institute
of Condensed Matter and Nanosciences, Université Catholique de Louvain, Louvain-la-Neuve 1348, Belgium
| | - Nikolay A. Tumanov
- Institute
of Condensed Matter and Nanosciences, Université Catholique de Louvain, Louvain-la-Neuve 1348, Belgium
| | - Voraksmy Ban
- Institute
of Condensed Matter and Nanosciences, Université Catholique de Louvain, Louvain-la-Neuve 1348, Belgium
| | - Heng Ji
- Department
of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
| | - Jiang Wei
- Department
of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, United States
| | - Michael W. Swift
- Department
of Physics, University of California, Santa Barbara, California 93106, United States
| | - Andriy H. Nevidomskyy
- Department
of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
| | - Douglas Natelson
- Department
of Physics and Astronomy, Rice University, Houston, Texas 77005, United States
- Department
of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
| |
Collapse
|
18
|
Lu X, Gretarsson H, Zhang R, Liu X, Luo H, Tian W, Laver M, Yamani Z, Kim YJ, Nevidomskyy AH, Si Q, Dai P. Avoided quantum criticality and magnetoelastic coupling in BaFe(2-x)Ni(x)As2. Phys Rev Lett 2013; 110:257001. [PMID: 23829752 DOI: 10.1103/physrevlett.110.257001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Indexed: 06/02/2023]
Abstract
We study the structural and magnetic orders in electron-doped BaFe(2-x)Ni(x)As2 by high-resolution synchrotron x-ray and neutron scatterings. Upon Ni doping x, the nearly simultaneous tetragonal-to-orthorhombic structural (T(s)) and antiferromagnetic (T(N)) phase transitions in BaFe2As2 are gradually suppressed and separated, resulting in T(s)>T(N) with increasing x, as was previously observed. However, the temperature separation between T(s) and T(N) decreases with increasing x for x≥0.065, tending toward a quantum bicritical point near optimal superconductivity at x≈0.1. The zero-temperature transition is preempted by the formation of a secondary incommensurate magnetic phase in the region 0.088≲x≲0.104, resulting in a finite value of T(N)≈T(c) + 10 K above the superconducting dome around x≈0.1. Our results imply an avoided quantum critical point, which is expected to strongly influence the properties of both the normal and superconducting states.
Collapse
Affiliation(s)
- Xingye Lu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Abstract
We propose a model for the intrinsic quantum criticality of β-YbAlB(4), in which a vortex in momentum space gives rise to a new type of Fermi surface singularity. The unquenched angular momentum of the |J=7/2,m(J)=±5/2> Yb 4f states generates a momentum-space line defect in the hybridization between 4f and conduction electrons, leading to a quasi-two-dimensional Fermi surface with a k(⊥)(4) dispersion and a singular density of states proportional to E(-1/2). We discuss the implications of this line node in momentum space for our current understanding of quantum criticality and its interplay with topology.
Collapse
Affiliation(s)
- Aline Ramires
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | | | | | | |
Collapse
|
20
|
Abstract
Strongly correlated materials are profoundly affected by the repulsive electron-electron interaction. This stands in contrast to many commonly used materials such as silicon and aluminum, whose properties are comparatively unaffected by the Coulomb repulsion. Correlated materials often have remarkable properties and transitions between distinct, competing phases with dramatically different electronic and magnetic orders. These rich phenomena are fascinating from the basic science perspective and offer possibilities for technological applications. This article looks at these materials through the lens of research performed at Rice University. Topics examined include: Quantum phase transitions and quantum criticality in "heavy fermion" materials and the iron pnictide high temperature superconductors; computational ab initio methods to examine strongly correlated materials and their interface with analytical theory techniques; layered dichalcogenides as example correlated materials with rich phases (charge density waves, superconductivity, hard ferromagnetism) that may be tuned by composition, pressure, and magnetic field; and nanostructure methods applied to the correlated oxides VO₂ and Fe₃O₄, where metal-insulator transitions can be manipulated by doping at the nanoscale or driving the system out of equilibrium. We conclude with a discussion of the exciting prospects for this class of materials.
Collapse
Affiliation(s)
- Emilia Morosan
- Department of Physics and Astronomy MS 61, Rice University, 6100 Main St., Houston, TX 77005, USA
| | | | | | | |
Collapse
|
21
|
Matsumoto Y, Nakatsuji S, Kuga K, Karaki Y, Horie N, Shimura Y, Sakakibara T, Nevidomskyy AH, Coleman P. Quantum Criticality Without Tuning in the Mixed Valence Compound β-YbAlB
4. Science 2011; 331:316-9. [PMID: 21252341 DOI: 10.1126/science.1197531] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Yosuke Matsumoto
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Satoru Nakatsuji
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Kentaro Kuga
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Yoshitomo Karaki
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Naoki Horie
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Yasuyuki Shimura
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Toshiro Sakakibara
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Andriy H. Nevidomskyy
- Center for Materials Theory, Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
- Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA
| | - Piers Coleman
- Center for Materials Theory, Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
- Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
| |
Collapse
|
22
|
Poltavets VV, Lokshin KA, Nevidomskyy AH, Croft M, Tyson TA, Hadermann J, Van Tendeloo G, Egami T, Kotliar G, ApRoberts-Warren N, Dioguardi AP, Curro NJ, Greenblatt M. Bulk magnetic order in a two-dimensional Ni1+/Ni2+ (d9/d8) nickelate, isoelectronic with superconducting cuprates. Phys Rev Lett 2010; 104:206403. [PMID: 20867044 DOI: 10.1103/physrevlett.104.206403] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2009] [Indexed: 05/29/2023]
Abstract
The Ni1+/Ni2+ states of nickelates have the identical (3d(9)/3d(8)) electronic configuration as Cu2+/Cu3+ in the high temperature superconducting cuprates, and are expected to show interesting properties. An intriguing question is whether mimicking the electronic and structural features of cuprates would also result in superconductivity in nickelates. Here we report experimental evidence for a bulklike magnetic transition in La4Ni3O8 at 105 K. Density functional theory calculations relate the transition to a spin density wave nesting instability of the Fermi surface.
Collapse
Affiliation(s)
- Viktor V Poltavets
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Abstract
We develop a simple scaling theory for the effect of Hund's interactions on the Kondo effect, showing how an exponential narrowing of the Kondo resonance develops in magnetic ions with large Hund's interaction. Our theory accounts for the exponential reduction of the Kondo temperature with spin S of the Hund's coupled moment, first observed in d-electron alloys in the 1960s, and more recently encountered in numerical calculations on multiband Hubbard models. We discuss the consequences of Kondo resonance narrowing for the Mott transition in d-band materials, particularly iron pnictides, and the narrow ESR linewidth recently observed in ferromagnetically correlated f-electron materials.
Collapse
Affiliation(s)
- Andriy H Nevidomskyy
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
| | | |
Collapse
|
24
|
Abstract
We analyze the magnetic and electronic properties of the quantum critical heavy fermion superconductor beta-YbAlB4, calculating the Fermi surface and the angular dependence of the extremal orbits relevant to the de Haas-van Alphen measurements. Using a combination of the realistic materials modeling and single-ion crystal field analysis, we are led to propose a layered Kondo lattice model for this system, in which two-dimensional boron layers are Kondo coupled via interlayer Yb moments in a Jz=+/-5/2 state. This model fits the measured single-ion magnetic susceptibility and predicts a substantial change in the electronic anisotropy as the system is pressure tuned through the quantum critical point.
Collapse
Affiliation(s)
- Andriy H Nevidomskyy
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
| | | |
Collapse
|
25
|
Nevidomskyy AH. Coexistence of ferromagnetism and superconductivity close to a quantum phase transition: the Heisenberg- to Ising-type crossover. Phys Rev Lett 2005; 94:097003. [PMID: 15783990 DOI: 10.1103/physrevlett.94.097003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2004] [Indexed: 05/24/2023]
Abstract
A microscopic mean-field theory of the phase coexistence between ferromagnetism and superconductivity in the weakly ferromagnetic itinerant electron system is constructed, while incorporating a realistic mechanism for superconducting pairing due to the exchange of critical spin fluctuations. The self-consistent solution of the resulting equations determines the superconducting transition temperature which is shown to depend strongly on the exchange splitting. The effect of phase crossover from isotropic (Heisenberg-like) to uniaxial (Ising-like) spin fluctuations near the quantum phase transition is analyzed and the generic phase diagram is obtained. This scenario is then applied to the case of itinerant ferromagnet ZrZn2, which sheds light on the proposed phase diagram of this compound. A possible explanation of superconductivity in UGe2 is also discussed.
Collapse
Affiliation(s)
- Andriy H Nevidomskyy
- Theory of Condensed Matter, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom.
| |
Collapse
|
26
|
Nevidomskyy AH, Csányi G, Payne MC. Chemically active substitutional nitrogen impurity in carbon nanotubes. Phys Rev Lett 2003; 91:105502. [PMID: 14525489 DOI: 10.1103/physrevlett.91.105502] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2003] [Indexed: 05/24/2023]
Abstract
We investigate the nitrogen substitutional impurity in semiconducting zigzag and metallic armchair single-wall carbon nanotubes using ab initio density functional theory. At low concentrations (less than 1 at. %), the defect state in a semiconducting tube becomes spatially localized and develops a flat energy level in the band gap. Such a localized state makes the impurity site chemically and electronically active. We find that if two neighboring tubes have their impurities facing one another, an intertube covalent bond forms. This finding opens an intriguing possibility for tunnel junctions, as well as the functionalization of suitably doped carbon nanotubes by selectively forming chemical bonds with ligands at the impurity site. If the intertube bond density is high enough, a highly packed bundle of interlinked single-wall nanotubes can form.
Collapse
Affiliation(s)
- Andriy H Nevidomskyy
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | | | | |
Collapse
|