1
|
Wu H, Chen L, Malinowski P, Jang BG, Deng Q, Scott K, Huang J, Ruff JPC, He Y, Chen X, Hu C, Yue Z, Oh JS, Teng X, Guo Y, Klemm M, Shi C, Shi Y, Setty C, Werner T, Hashimoto M, Lu D, Yilmaz T, Vescovo E, Mo SK, Fedorov A, Denlinger JD, Xie Y, Gao B, Kono J, Dai P, Han Y, Xu X, Birgeneau RJ, Zhu JX, da Silva Neto EH, Wu L, Chu JH, Si Q, Yi M. Reversible non-volatile electronic switching in a near-room-temperature van der Waals ferromagnet. Nat Commun 2024; 15:2739. [PMID: 38548765 PMCID: PMC10978849 DOI: 10.1038/s41467-024-46862-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 03/13/2024] [Indexed: 04/01/2024] Open
Abstract
Non-volatile phase-change memory devices utilize local heating to toggle between crystalline and amorphous states with distinct electrical properties. Expanding on this kind of switching to two topologically distinct phases requires controlled non-volatile switching between two crystalline phases with distinct symmetries. Here, we report the observation of reversible and non-volatile switching between two stable and closely related crystal structures, with remarkably distinct electronic structures, in the near-room-temperature van der Waals ferromagnet Fe5-δGeTe2. We show that the switching is enabled by the ordering and disordering of Fe site vacancies that results in distinct crystalline symmetries of the two phases, which can be controlled by a thermal annealing and quenching method. The two phases are distinguished by the presence of topological nodal lines due to the preserved global inversion symmetry in the site-disordered phase, flat bands resulting from quantum destructive interference on a bipartite lattice, and broken inversion symmetry in the site-ordered phase.
Collapse
Affiliation(s)
- Han Wu
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
| | - Lei Chen
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
| | - Paul Malinowski
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Bo Gyu Jang
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA
- Department of Advanced Materials Engineering for Information and Electronics, Kyung Hee University, Yongin, Republic of Korea
| | - Qinwen Deng
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, USA
| | - Kirsty Scott
- Department of Physics, Yale University, New Haven, CT, USA
- Energy Sciences Institute, Yale University, West Haven, CT, USA
- Department of Physics and Astronomy, University of California, Davis, CA, USA
- Department of Applied Physics, Yale University, New Haven, CT, USA
| | - Jianwei Huang
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
| | - Jacob P C Ruff
- Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY, USA
| | - Yu He
- Department of Physics, University of California, Berkeley, CA, USA
| | - Xiang Chen
- Department of Physics, University of California, Berkeley, CA, USA
| | - Chaowei Hu
- Department of Physics, University of Washington, Seattle, WA, USA
- Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA
| | - Ziqin Yue
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
| | - Ji Seop Oh
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
- Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA
| | - Xiaokun Teng
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
| | - Yucheng Guo
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
| | - Mason Klemm
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
| | - Chuqiao Shi
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, USA
| | - Yue Shi
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Chandan Setty
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
| | - Tyler Werner
- Department of Applied Physics, Yale University, New Haven, CT, USA
| | - Makoto Hashimoto
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Donghui Lu
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Turgut Yilmaz
- National Synchrotron Light Source II, Brookhaven National Lab, Upton, NY, USA
| | - Elio Vescovo
- National Synchrotron Light Source II, Brookhaven National Lab, Upton, NY, USA
| | - Sung-Kwan Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Alexei Fedorov
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | | | - Yaofeng Xie
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
| | - Bin Gao
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
| | - Junichiro Kono
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, USA
- Departments of Electrical and Computer Engineering, Rice University, Houston, TX, USA
| | - Pengcheng Dai
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
| | - Yimo Han
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX, USA
| | - Xiaodong Xu
- Department of Physics, University of Washington, Seattle, WA, USA
- Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA
| | - Robert J Birgeneau
- Department of Physics, University of California, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - Jian-Xin Zhu
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Eduardo H da Silva Neto
- Department of Physics, Yale University, New Haven, CT, USA
- Energy Sciences Institute, Yale University, West Haven, CT, USA
- Department of Physics and Astronomy, University of California, Davis, CA, USA
- Department of Applied Physics, Yale University, New Haven, CT, USA
| | - Liang Wu
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, USA
| | - Jiun-Haw Chu
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Qimiao Si
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA
| | - Ming Yi
- Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice University, Houston, TX, USA.
| |
Collapse
|
2
|
Setty C, Baggioli M, Zaccone A. Anharmonic theory of superconductivity and its applications to emerging quantum materials. J Phys Condens Matter 2024; 36:173002. [PMID: 38252997 DOI: 10.1088/1361-648x/ad2159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 01/22/2024] [Indexed: 01/24/2024]
Abstract
The role of anharmonicity on superconductivity has often been disregarded in the past. Recently, it has been recognized that anharmonic decoherence could play a fundamental role in determining the superconducting properties (electron-phonon coupling, critical temperature, etc) of a large class of materials, including systems close to structural soft-mode instabilities, amorphous solids and metals under extreme high-pressure conditions. Here, we review recent theoretical progress on the role of anharmonic effects, and in particular certain universal properties of anharmonic damping, on superconductivity. Our focus regards the combination of microscopic-agnostic effective theories for bosonic mediators with the well-established BCS theory and Migdal-Eliashberg theory for superconductivity. We discuss in detail the theoretical frameworks, their possible implementation within first-principles methods, and the experimental probes for anharmonic decoherence. Finally, we present several concrete applications to emerging quantum materials, including hydrides, ferroelectrics and systems with charge density wave instabilities.
Collapse
Affiliation(s)
- Chandan Setty
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX 77005, United States of America
| | - Matteo Baggioli
- Wilczek Quantum Center, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, People's Republic of China
| | - Alessio Zaccone
- Department of Physics 'A. Pontremoli', University of Milan, via Celoria 16, 20133 Milan, Italy
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, CB30HE Cambridge, United Kingdom
| |
Collapse
|
3
|
Chen L, Lowder DT, Bakali E, Andrews AM, Schrenk W, Waas M, Svagera R, Eguchi G, Prochaska L, Wang Y, Setty C, Sur S, Si Q, Paschen S, Natelson D. Shot noise in a strange metal. Science 2023; 382:907-911. [PMID: 37995251 DOI: 10.1126/science.abq6100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 10/12/2023] [Indexed: 11/25/2023]
Abstract
Strange-metal behavior has been observed in materials ranging from high-temperature superconductors to heavy fermion metals. In conventional metals, current is carried by quasiparticles; although it has been suggested that quasiparticles are absent in strange metals, direct experimental evidence is lacking. We measured shot noise to probe the granularity of the current-carrying excitations in nanowires of the heavy fermion strange metal YbRh2Si2. When compared with conventional metals, shot noise in these nanowires is strongly suppressed. This suppression cannot be attributed to either electron-phonon or electron-electron interactions in a Fermi liquid, which suggests that the current is not carried by well-defined quasiparticles in the strange-metal regime that we probed. Our work sets the stage for similar studies of other strange metals.
Collapse
Affiliation(s)
- Liyang Chen
- Applied Physics Graduate Program, Rice University, TX 77005, USA
| | - Dale T Lowder
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX 77005, USA
| | - Emine Bakali
- Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria
| | - Aaron Maxwell Andrews
- Institute of Solid State Electronics, TU Wien, Gußhausstraße 25-25a, Gebäude CH, 1040 Vienna, Austria
| | - Werner Schrenk
- Center for Micro and Nanostructures, TU Wien, Gußhausstraße 25-25a, Gebäude CH, 1040 Vienna, Austria
| | - Monika Waas
- Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria
| | - Robert Svagera
- Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria
| | - Gaku Eguchi
- Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria
| | - Lukas Prochaska
- Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria
| | - Yiming Wang
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX 77005, USA
| | - Chandan Setty
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX 77005, USA
| | - Shouvik Sur
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX 77005, USA
| | - Qimiao Si
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX 77005, USA
| | - Silke Paschen
- Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria
| | - Douglas Natelson
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX 77005, USA
- Department of Electrical and Computer Engineering, Rice University, Houston, TX 77005, USA
- Department of Materials Science and NanoEngineering, Rice University, Houston, TX 77005, USA
| |
Collapse
|
4
|
Setty C, Fanfarillo L, Hirschfeld PJ. Mechanism for fluctuating pair density wave. Nat Commun 2023; 14:3181. [PMID: 37264032 DOI: 10.1038/s41467-023-38956-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 05/16/2023] [Indexed: 06/03/2023] Open
Abstract
In weakly coupled BCS superconductors, only electrons within a tiny energy window around the Fermi energy, EF, form Cooper pairs. This may not be the case in strong coupling superconductors such as cuprates, FeSe, SrTiO3 or cold atom condensates where the pairing scale, EB, becomes comparable or even larger than EF. In cuprates, for example, a plausible candidate for the pseudogap state at low doping is a fluctuating pair density wave, but no microscopic model has yet been found which supports such a state. In this work, we write an analytically solvable model to examine pairing phases in the strongly coupled regime and in the presence of anisotropic interactions. Already for moderate coupling we find an unusual finite temperature phase, below an instability temperature Ti, where local pair correlations have non-zero center-of-mass momentum but lack long-range order. At low temperature, this fluctuating pair density wave can condense either to a uniform d-wave superconductor or the widely postulated pair-density wave phase depending on the interaction strength. Our minimal model offers a unified framework to understand the emergence of both fluctuating and long range pair density waves in realistic systems.
Collapse
Affiliation(s)
- Chandan Setty
- Department of Physics, University of Florida, Gainesville, FL, USA.
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX, 77005, USA.
| | - Laura Fanfarillo
- Department of Physics, University of Florida, Gainesville, FL, USA.
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136, Trieste, Italy.
| | - P J Hirschfeld
- Department of Physics, University of Florida, Gainesville, FL, USA.
| |
Collapse
|
5
|
Jiang C, Beneduce E, Baggioli M, Setty C, Zaccone A. Possible enhancement of the superconductingTcdue to sharp Kohn-like soft phonon anomalies. J Phys Condens Matter 2023; 35:164003. [PMID: 36808073 DOI: 10.1088/1361-648x/acbd0a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 02/17/2023] [Indexed: 06/18/2023]
Abstract
Phonon softening is a ubiquitous phenomenon in condensed matter systems which is often associated with charge density wave (CDW) instabilities and anharmonicity. The interplay between phonon softening, CDW and superconductivity is a topic of intense debate. In this work, the effects of anomalous soft phonon instabilities on superconductivity are studied based on a recently developed theoretical framework that accounts for phonon damping and softening within the Migdal-Eliashberg theory. Model calculations show that the phonon softening in the form of a sharp dip in the phonon dispersion relation, either acoustic or optical (including the case of Kohn-type anomalies typically associated with CDW), can cause a manifold increase of the electron-phonon coupling constantλ. This, under certain conditions, which are consistent with the concept of optimal frequency introduced by Bergmann and Rainer, can produce a large increase of the superconducting transition temperatureTc. In summary, our results suggest the possibility of reaching high-temperature superconductivity by exploiting soft phonon anomalies restricted in momentum space.
Collapse
Affiliation(s)
- Cunyuan Jiang
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Enrico Beneduce
- Department of Physics "A. Pontremoli", University of Milan, via Celoria 16, 20133 Milan, Italy
| | - Matteo Baggioli
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
- Wilczek Quantum Center, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, People's Republic of China
| | - Chandan Setty
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX 77005, United States of America
| | - Alessio Zaccone
- Department of Physics "A. Pontremoli", University of Milan, via Celoria 16, 20133 Milan, Italy
| |
Collapse
|
6
|
Yin JX, Jiang YX, Teng X, Hossain MS, Mardanya S, Chang TR, Ye Z, Xu G, Denner MM, Neupert T, Lienhard B, Deng HB, Setty C, Si Q, Chang G, Guguchia Z, Gao B, Shumiya N, Zhang Q, Cochran TA, Multer D, Yi M, Dai P, Hasan MZ. Discovery of Charge Order and Corresponding Edge State in Kagome Magnet FeGe. Phys Rev Lett 2022; 129:166401. [PMID: 36306757 DOI: 10.1103/physrevlett.129.166401] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
Kagome materials often host exotic quantum phases, including spin liquids, Chern gap, charge density wave, and superconductivity. Existing scanning microscopy studies of the kagome charge order have been limited to nonkagome surface layers. Here, we tunnel into the kagome lattice of FeGe to uncover features of the charge order. Our spectroscopic imaging identifies a 2×2 charge order in the magnetic kagome lattice, resembling that discovered in kagome superconductors. Spin mapping across steps of unit cell height demonstrates the existence of spin-polarized electrons with an antiferromagnetic stacking order. We further uncover the correlation between antiferromagnetism and charge order anisotropy, highlighting the unusual magnetic coupling of the charge order. Finally, we detect a pronounced edge state within the charge order energy gap, which is robust against the irregular shape fluctuations of the kagome lattice edges. We discuss our results with the theoretically considered topological features of the kagome charge order including unconventional magnetism and bulk-boundary correspondence.
Collapse
Affiliation(s)
- Jia-Xin Yin
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Yu-Xiao Jiang
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Xiaokun Teng
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Md Shafayat Hossain
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Sougata Mardanya
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
| | - Tay-Rong Chang
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
| | - Zijin Ye
- Wuhan National High Magnetic Field Center & School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Gang Xu
- Wuhan National High Magnetic Field Center & School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - M Michael Denner
- Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Titus Neupert
- Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Benjamin Lienhard
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Han-Bin Deng
- Laboratory for Quantum Emergence, department of physics, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Chandan Setty
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Qimiao Si
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Guoqing Chang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798, Singapore
| | - Zurab Guguchia
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Bin Gao
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Nana Shumiya
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Qi Zhang
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Tyler A Cochran
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Daniel Multer
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Ming Yi
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Pengcheng Dai
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - M Zahid Hasan
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, USA
- Quantum Science Center, Oak Ridge, Tennessee 37830, USA
| |
Collapse
|
7
|
Padhi B, Setty C, Phillips PW. Doped Twisted Bilayer Graphene near Magic Angles: Proximity to Wigner Crystallization, Not Mott Insulation. Nano Lett 2018; 18:6175-6180. [PMID: 30185049 DOI: 10.1021/acs.nanolett.8b02033] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We devise a model to explain why twisted bilayer graphene exhibits insulating behavior when ν = 2 or 3 charges occupy a unit moiré cell, a feature attributed to Mottness per previous work but not for ν = 1, clearly inconsistent with Mott insulation. We compute rs = EU/ EK, where EU and EK are the potential and kinetic energies, respectively, and show that (i) the Mott criterion lies at a density larger than experimental values by a factor of 104 and (ii) a transition to a series of Wigner crystalline states exists as a function of ν. We find that, for ν = 1, rs fails to cross the threshold ( rs = 37) for the triangular lattice, and metallic transport ensues. However, for ν = 2 and ν = 3, the thresholds rs = 22 and rs = 17, respectively, are satisfied for a transition to Wigner crystals (WCs) with a honeycomb (ν = 2) and a kagome (ν = 3) structure. We posit that such crystalline states form the correct starting point for analyzing superconductivity.
Collapse
Affiliation(s)
- Bikash Padhi
- Department of Physics and Institute for Condensed Matter Theory , University of Illinois at Urbana-Champaign , 1110 West Green Street , Urbana , Illinois 61801 , United States
| | - Chandan Setty
- Department of Physics and Institute for Condensed Matter Theory , University of Illinois at Urbana-Champaign , 1110 West Green Street , Urbana , Illinois 61801 , United States
| | - Philip W Phillips
- Department of Physics and Institute for Condensed Matter Theory , University of Illinois at Urbana-Champaign , 1110 West Green Street , Urbana , Illinois 61801 , United States
| |
Collapse
|
8
|
|
9
|
Zhao J, Rotundu CR, Marty K, Matsuda M, Zhao Y, Setty C, Bourret-Courchesne E, Hu J, Birgeneau RJ. Effect of electron correlations on magnetic excitations in the isovalently doped iron-based superconductor Ba(Fe(1-x)Ru(x))(2)As(2). Phys Rev Lett 2013; 110:147003. [PMID: 25167027 DOI: 10.1103/physrevlett.110.147003] [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: 01/12/2012] [Indexed: 06/03/2023]
Abstract
Magnetic correlations in isovalently doped Ba(Fe(1-x)Ru(x))(2)As(2) (x = 0.25, T(c) = 14.5 K; x = 0.35, T(c) = 20 K) are studied by elastic and inelastic neutron scattering techniques. A relatively large superconducting spin gap accompanied by a weak resonance mode is observed in the superconducting state in both samples. In the normal state, the magnetic excitation intensity is dramatically reduced with increasing Ru doping toward the optimally doped regime. Our results favor that the weakening of the electron-electron correlations by Ru doping is responsible for the dampening of the resonance mode, as well as the suppression of the normal state antiferromagnetic correlations near the optimally doped regime in this system.
Collapse
Affiliation(s)
- Jun Zhao
- Department of Physics, and Laboratory of Advanced Materials, State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, People's Republic of China and Department of Physics, University of California, Berkeley, California 94720, USA and Miller Institute for Basic Research in Science, Berkeley, California 94720, USA
| | - C R Rotundu
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - K Marty
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M Matsuda
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Y Zhao
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA and Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
| | - C Setty
- Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA
| | - E Bourret-Courchesne
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jiangping Hu
- Department of Physics, Purdue University, West Lafayette, Indiana 47907, USA
| | - R J Birgeneau
- Department of Physics, University of California, Berkeley, California 94720, USA and Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| |
Collapse
|