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Lin MK, Hlevyack JA, Zhao C, Dudin P, Avila J, Mo SK, Cheng CM, Abbamonte P, Shoemaker DP, Chiang TC. Unconventional Spectral Gaps Induced by Charge Density Waves in the Weyl Semimetal (TaSe 4) 2I. NANO LETTERS 2024; 24:8778-8783. [PMID: 38976362 PMCID: PMC11261618 DOI: 10.1021/acs.nanolett.4c02701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Revised: 07/02/2024] [Accepted: 07/02/2024] [Indexed: 07/10/2024]
Abstract
Coupling Weyl quasiparticles and charge density waves (CDWs) can lead to fascinating band renormalization and many-body effects beyond band folding and Peierls gaps. For the quasi-one-dimensional chiral compound (TaSe4)2I with an incommensurate CDW transition at TC = 263 K, photoemission mappings thus far are intriguing due to suppressed emission near the Fermi level. Models for this unconventional behavior include axion insulator phases, correlation pseudogaps, polaron subbands, bipolaron bound states, etc. Our photoemission measurements show sharp quasiparticle bands crossing the Fermi level at T > TC, but for T < TC, these bands retain their dispersions with no Peierls or axion gaps at the Weyl points. Instead, occupied band edges recede from the Fermi level, opening a spectral gap. Our results confirm localization of quasiparticles (holes created by photoemission) is the key physics, which suppresses spectral weights over an energy window governed by incommensurate modulation and inherent phase defects of CDW.
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Affiliation(s)
- Meng-Kai Lin
- Department
of Physics, National Central University, Taoyuan 32001, Taiwan
| | - Joseph Andrew Hlevyack
- Department
of Physics, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Chengxi Zhao
- Department
of Materials Science and Engineering, University
of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Pavel Dudin
- Synchrotron
SOLEIL and Universite Paris-Saclay, L’Orme des Merisiers, BP48, 91190 Saint-Aubin, France
| | - José Avila
- Synchrotron
SOLEIL and Universite Paris-Saclay, L’Orme des Merisiers, BP48, 91190 Saint-Aubin, France
| | - Sung-Kwan Mo
- Advanced
Light Source, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Cheng-Maw Cheng
- National
Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Peter Abbamonte
- Department
of Physics, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Daniel P. Shoemaker
- Department
of Materials Science and Engineering, University
of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Tai-Chang Chiang
- Department
of Physics, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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Kondo T, Ochi M, Nakayama M, Taniguchi H, Akebi S, Kuroda K, Arita M, Sakai S, Namatame H, Taniguchi M, Maeno Y, Arita R, Shin S. Orbital-Dependent Band Narrowing Revealed in an Extremely Correlated Hund's Metal Emerging on the Topmost Layer of Sr_{2}RuO_{4}. PHYSICAL REVIEW LETTERS 2016; 117:247001. [PMID: 28009182 DOI: 10.1103/physrevlett.117.247001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Indexed: 06/06/2023]
Abstract
We use a surface-selective angle-resolved photoemission spectroscopy and unveil the electronic nature on the topmost layer of Sr_{2}RuO_{4} crystal, consisting of slightly rotated RuO_{6} octahedrons. The γ band derived from the 4d_{xy} orbital is found to be about three times narrower than that for the bulk. This strongly contrasts with a subtle variation seen in the α and β bands derived from the one-dimensional 4d_{xz/yz}. This anomaly is reproduced by the dynamical mean-field theory calculations, introducing not only the on-site Hubbard interaction but also the significant Hund's coupling. We detect a coherence-to-incoherence crossover theoretically predicted for Hund's metals, which has been recognized only recently. The crossover temperature in the surface is about half that of the bulk, indicating that the naturally generated monolayer of reconstructed Sr_{2}RuO_{4} is extremely correlated and well isolated from the underlying crystal.
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Affiliation(s)
- Takeshi Kondo
- ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - M Ochi
- Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - M Nakayama
- ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - H Taniguchi
- Department of Materials Science and Engineering, Iwate University, Morioka 020-8551, Japan
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - S Akebi
- ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - K Kuroda
- ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - M Arita
- Hiroshima Synchrotron Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan
| | - S Sakai
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - H Namatame
- Hiroshima Synchrotron Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan
| | - M Taniguchi
- Hiroshima Synchrotron Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Y Maeno
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - R Arita
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - S Shin
- ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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Stricker D, Mravlje J, Berthod C, Fittipaldi R, Vecchione A, Georges A, van der Marel D. Optical response of Sr2RuO4 reveals universal fermi-liquid scaling and quasiparticles beyond Landau theory. PHYSICAL REVIEW LETTERS 2014; 113:087404. [PMID: 25192127 DOI: 10.1103/physrevlett.113.087404] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Indexed: 06/03/2023]
Abstract
We report optical measurements demonstrating that the low-energy relaxation rate (1/τ) of the conduction electrons in Sr(2)RuO(4) obeys scaling relations for its frequency (ω) and temperature (T) dependence in accordance with Fermi-liquid theory. In the thermal relaxation regime, 1/τ ∝ (ħω)(2)+(pπk(B)T)(2) with p = 2, and ω/T scaling applies. Many-body electronic structure calculations using dynamical mean-field theory confirm the low-energy Fermi-liquid scaling and provide quantitative understanding of the deviations from Fermi-liquid behavior at higher energy and temperature. The excess optical spectral weight in this regime provides evidence for strongly dispersing "resilient" quasiparticle excitations above the Fermi energy.
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Affiliation(s)
- D Stricker
- Département de Physique de la Matière Condensée, Université de Genève, 24 quai Ernest-Ansermet, 1211 Genève 4, Switzerland
| | - J Mravlje
- Jožef Stefan Institute, Jamova 39, Ljubljana 1000, Slovenia
| | - C Berthod
- Département de Physique de la Matière Condensée, Université de Genève, 24 quai Ernest-Ansermet, 1211 Genève 4, Switzerland
| | - R Fittipaldi
- CNR-SPIN, and Dipartimento di Fisica "E. R. Caianiello", Universita di Salerno, I-84084 Fisciano (Salerno) Italy
| | - A Vecchione
- CNR-SPIN, and Dipartimento di Fisica "E. R. Caianiello", Universita di Salerno, I-84084 Fisciano (Salerno) Italy
| | - A Georges
- Département de Physique de la Matière Condensée, Université de Genève, 24 quai Ernest-Ansermet, 1211 Genève 4, Switzerland and Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France and Centre de Physique Théorique, École Polytechnique, CNRS, 91128 Palaiseau, France
| | - D van der Marel
- Département de Physique de la Matière Condensée, Université de Genève, 24 quai Ernest-Ansermet, 1211 Genève 4, Switzerland
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