Unconventional thermal metallic state of charge-neutral fermions in an insulator

Sato, Y.; Xiang, Z.; Kasahara, Y.; Taniguchi, T.; Kasahara, S.; Chen, L.; Asaba, T.; Tinsman, C.; Murayama, H.; Tanaka, O.; Mizukami, Y.; Shibauchi, T.; Iga, F.; Singleton, John; Li, Lu; Matsuda, Y.

doi:10.1038/s41567-019-0552-2

Title: Unconventional thermal metallic state of charge-neutral fermions in an insulator

Journal Article · 01 July 2019 · Nature Physics

DOI: https://doi.org/10.1038/s41567-019-0552-2 · OSTI ID:1764959

^[1]; Xiang, Z. ^[2]; Kasahara, Y. ^[1]; Taniguchi, T. ^[1];

^[1]; Chen, L. ^[2];

^[3]; Tinsman, C. ^[2]; Murayama, H. ^[1]; Tanaka, O. ^[4]; Mizukami, Y. ^[4];

^[4]; Iga, F. ^[5];

^[6];

^[2];

^[1]

Kyoto Univ. (Japan)
Univ. of Michigan, Ann Arbor, MI (United States)
Univ. of Michigan, Ann Arbor, MI (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Univ. of Tokyo, Chiba (Japan)
Ibaraki Univ., Mito (Japan)
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Quantum oscillations in transport and thermodynamic parameters at high magnetic fields are an unambiguous signature of the Fermi surface, the defining characteristic of a metal. Recent observations of quantum oscillations in insulating SmB₆ and YbB₁₂, therefore, have been a big surprise—despite the large charge gap inferred from the insulating behaviour of the resistivity, these compounds seemingly host a Fermi surface at high magnetic fields. However, the nature of the ground state in zero field has been little explored. Here, we report the use of low-temperature heat-transport measurements to discover gapless, itinerant, charge-neutral excitations in the ground state of YbB₁₂. At zero field, sizeable linear temperature-dependent terms in the heat capacity and thermal conductivity are clearly resolved in the zero-temperature limit, indicating the presence of gapless fermionic excitations with an itinerant character. Remarkably, linear temperature-dependent thermal conductivity leads to a spectacular violation of the Wiedemann–Franz law: the Lorenz ratio is 10⁴–10⁵ times larger than that expected in conventional metals, indicating that YbB₁₂ is a charge insulator and a thermal metal. Furthermore, we find that these fermions couple to magnetic fields, despite their charge neutrality. Our findings expose novel quasiparticles in this unconventional quantum state.

View Accepted Manuscript (DOE)

Cite

Export

Save

Research Organization:: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Organization:: USDOE

Grant/Contract Number:: 89233218CNA000001

OSTI ID:: 1764959

Alternate ID(s):: OSTI ID: 1782638

Report Number(s):: LA-UR-18-28381; LA-UR-19-26760

Journal Information:: Nature Physics, Vol. 15, Issue 9; ISSN 1745-2473

Publisher:: Nature Publishing Group (NPG)Copyright Statement

Country of Publication:: United States

Language:: English

References (61)

Orbital magnetic field effects in spin liquid with spinon Fermi sea: Possible application to κ − ( ET ) 2 Cu 2 ( C N ) 3 Motrunich, Olexei I. Physical Review B, Vol. 73, Issue 15 https://doi.org/10.1103/PhysRevB.73.155115	journal	April 2006
Quantum Oscillations without a Fermi Surface and the Anomalous de Haas–van Alphen Effect Knolle, Johannes; Cooper, Nigel R. Physical Review Letters, Vol. 115, Issue 14 https://doi.org/10.1103/PhysRevLett.115.146401	journal	September 2015
Topological Kondo Insulators Dzero, Maxim; Sun, Kai; Galitski, Victor Physical Review Letters, Vol. 104, Issue 10 https://doi.org/10.1103/PhysRevLett.104.106408	journal	March 2010
Field-dependent heat transport in the Kondo insulator SmB 6 : Phonons scattered by magnetic impurities Boulanger, M-E.; Laliberté, F.; Dion, M. Physical Review B, Vol. 97, Issue 24 https://doi.org/10.1103/PhysRevB.97.245141	journal	June 2018
Low-temperature thermal properties of yttrium and lutetium dodecaborides Czopnik, A.; Shitsevalova, N.; Pluzhnikov, V. Journal of Physics: Condensed Matter, Vol. 17, Issue 38 https://doi.org/10.1088/0953-8984/17/38/003	journal	September 2005
Spin liquids in frustrated magnets Balents, Leon Nature, Vol. 464, Issue 7286 https://doi.org/10.1038/nature08917	journal	March 2010
Theory of the Thermal Hall Effect in Quantum Magnets Katsura, Hosho; Nagaosa, Naoto; Lee, Patrick A. Physical Review Letters, Vol. 104, Issue 6 https://doi.org/10.1103/PhysRevLett.104.066403	journal	February 2010
Lattice dynamics in the Kondo insulator YbB12 Nemkovski, K. S.; Alekseev, P. A.; Mignot, J. -M. Journal of Solid State Chemistry, Vol. 179, Issue 9 https://doi.org/10.1016/j.jssc.2006.01.061	journal	September 2006
Specific-Heat Measurements of the Gap Structure of the Organic Superconductors κ − ( ET ) 2 Cu [ N ( CN ) 2 ] Br and κ − ( ET ) 2 Cu ( NCS ) 2 Taylor, O. J.; Carrington, A.; Schlueter, J. A. Physical Review Letters, Vol. 99, Issue 5 https://doi.org/10.1103/PhysRevLett.99.057001	journal	July 2007
Two-dimensional Fermi surfaces in Kondo insulator SmB ₆ Li, G.; Xiang, Z.; Yu, F. Science, Vol. 346, Issue 6214 https://doi.org/10.1126/science.1250366	journal	December 2014
Quantum Oscillation from In-Gap States and a Non-Hermitian Landau Level Problem Shen, Huitao; Fu, Liang Physical Review Letters, Vol. 121, Issue 2 https://doi.org/10.1103/PhysRevLett.121.026403	journal	July 2018
Evidence for Short-Range Antiferromagnetic Fluctuations in Kondo-Insulating YbB 12 Mignot, J. -M.; Alekseev, P. A.; Nemkovski, K. S. Physical Review Letters, Vol. 94, Issue 24 https://doi.org/10.1103/PhysRevLett.94.247204	journal	June 2005
Sm B 6 : Kondo Insulator or Exotic Metal? Cooley, J. C.; Aronson, M. C.; Fisk, Z. Physical Review Letters, Vol. 74, Issue 9 https://doi.org/10.1103/PhysRevLett.74.1629	journal	February 1995
Surface Kondo effect and non-trivial metallic state of the Kondo insulator YbB12 Hagiwara, Kenta; Ohtsubo, Yoshiyuki; Matsunami, Masaharu Nature Communications, Vol. 7, Issue 1 https://doi.org/10.1038/ncomms12690	journal	August 2016
Excitons in topological Kondo insulators: Theory of thermodynamic and transport anomalies in SmB 6 Knolle, Johannes; Cooper, Nigel R. Physical Review Letters, Vol. 118, Issue 9 https://doi.org/10.1103/PhysRevLett.118.096604	journal	March 2017
Emergence of nontrivial magnetic excitations in a spin-liquid state of kagomé volborthite Watanabe, Daiki; Sugii, Kaori; Shimozawa, Masaaki Proceedings of the National Academy of Sciences, Vol. 113, Issue 31 https://doi.org/10.1073/pnas.1524076113	journal	July 2016
Bulk and surface electronic properties of SmB 6 : A hard x-ray photoelectron spectroscopy study Utsumi, Y.; Kasinathan, D.; Ko, K. -T. Physical Review B, Vol. 96, Issue 15 https://doi.org/10.1103/PhysRevB.96.155130	journal	October 2017
Unconventional Fermi surface in an insulating state Tan, B. S.; Hsu, Y. - T.; Zeng, B. Science, Vol. 349, Issue 6245 https://doi.org/10.1126/science.aaa7974	journal	July 2015
The ground-state phase diagram of the one-dimensional Kondo lattice model Tsunetsugu, Hirokazu; Sigrist, Manfred; Ueda, Kazuo Reviews of Modern Physics, Vol. 69, Issue 3 https://doi.org/10.1103/RevModPhys.69.809	journal	July 1997
Highly Mobile Gapless Excitations in a Two-Dimensional Candidate Quantum Spin Liquid Yamashita, M.; Nakata, N.; Senshu, Y. Science, Vol. 328, Issue 5983 https://doi.org/10.1126/science.1188200	journal	June 2010
Gapless spin liquid of an organic triangular compound evidenced by thermodynamic measurements Yamashita, Satoshi; Yamamoto, Takashi; Nakazawa, Yasuhiro Nature Communications, Vol. 2, Issue 1 https://doi.org/10.1038/ncomms1274	journal	April 2011
Topological Crystalline Kondo Insulator in Mixed Valence Ytterbium Borides Weng, Hongming; Zhao, Jianzhou; Wang, Zhijun Physical Review Letters, Vol. 112, Issue 1 https://doi.org/10.1103/PhysRevLett.112.016403	journal	January 2014
Anomalous low-temperature thermal properties of glasses and spin glasses Anderson, P. w.; Halperin, B. I.; Varma, c. M. Philosophical Magazine, Vol. 25, Issue 1 https://doi.org/10.1080/14786437208229210	journal	January 1972
Electronic structure and bulk properties of MB6 and MB12 borides Grechnev, G. E.; Baranovskiy, A. E.; Fil, V. D. Low Temperature Physics, Vol. 34, Issue 11 https://doi.org/10.1063/1.3009588	journal	November 2008
Mixed-valence insulators with neutral Fermi surfaces Chowdhury, Debanjan; Sodemann, Inti; Senthil, T. Nature Communications, Vol. 9, Issue 1 https://doi.org/10.1038/s41467-018-04163-2	journal	May 2018
Hybridization gap formation in the Kondo insulator YbB 12 observed using time-resolved photoemission spectroscopy Okawa, M.; Ishida, Y.; Takahashi, M. Physical Review B, Vol. 92, Issue 16 https://doi.org/10.1103/PhysRevB.92.161108	journal	October 2015
Kondo-semiconductor to Kondo-impurity transition in the heat capacity of Yb1−xLuxB12 Iga, F.; Hiura, S.; Klijn, J. Physica B: Condensed Matter, Vol. 259-261 https://doi.org/10.1016/S0921-4526(98)01096-5	journal	January 1999
Heavy fermion semiconductors Riseborough, Peter S. Advances in Physics, Vol. 49, Issue 3 https://doi.org/10.1080/000187300243345	journal	May 2000
Quantum Oscillation in Narrow-Gap Topological Insulators Zhang, Long; Song, Xue-Yang; Wang, Fa Physical Review Letters, Vol. 116, Issue 4 https://doi.org/10.1103/PhysRevLett.116.046404	journal	January 2016
Bulk Fermi Surface of Charge-Neutral Excitations in SmB 6 or Not: A Heat-Transport Study Xu, Y.; Cui, S.; Dong, J. K. Physical Review Letters, Vol. 116, Issue 24 https://doi.org/10.1103/PhysRevLett.116.246403	journal	June 2016
Universality of thermal transport in amorphous nanowires at low temperatures Tavakoli, Adib; Blanc, Christophe; Ftouni, Hossein Physical Review B, Vol. 95, Issue 16 https://doi.org/10.1103/PhysRevB.95.165411	journal	April 2017
Quantum oscillations of electrical resistivity in an insulator Xiang, Z.; Kasahara, Y.; Asaba, T. Science, Vol. 362, Issue 6410 https://doi.org/10.1126/science.aap9607	journal	August 2018
Single crystal growth and physical properties of Kondo insulator YbB12 Iga, F.; Shimizu, N.; Takabatake, T. Journal of Magnetism and Magnetic Materials, Vol. 177-181 https://doi.org/10.1016/S0304-8853(97)00493-9	journal	January 1998
Quantum oscillations in insulators with neutral Fermi surfaces Sodemann, Inti; Chowdhury, Debanjan; Senthil, T. Physical Review B, Vol. 97, Issue 4 https://doi.org/10.1103/PhysRevB.97.045152	journal	January 2018
171Yb NMR in the Kondo semiconductor YbB12 Ikushima, K.; Kato, Y.; Takigawa, M. Physica B: Condensed Matter, Vol. 281-282 https://doi.org/10.1016/S0921-4526(99)00815-7	journal	June 2000
Direct observation of the spin texture in SmB6 as evidence of the topological Kondo insulator Xu, N.; Biswas, P. K.; Dil, J. H. Nature Communications, Vol. 5, Issue 1 https://doi.org/10.1038/ncomms5566	journal	July 2014
Non-Hermitian perspective of the band structure in heavy-fermion systems Yoshida, Tsuneya; Peters, Robert; Kawakami, Norio Physical Review B, Vol. 98, Issue 3 https://doi.org/10.1103/PhysRevB.98.035141	journal	July 2018
Thermal conductivity of individual silicon nanowires Li, Deyu; Wu, Yiying; Kim, Philip Applied Physics Letters, Vol. 83, Issue 14, p. 2934-2936 https://doi.org/10.1063/1.1616981	journal	October 2003
Interaction Driven Subgap Spin Exciton in the Kondo Insulator SmB 6 Fuhrman, W. T.; Leiner, J.; Nikolić, P. Physical Review Letters, Vol. 114, Issue 3 https://doi.org/10.1103/PhysRevLett.114.036401	journal	January 2015
Magnetization Process of the Kondo Insulator YbB ₁₂ in Ultrahigh Magnetic Fields Terashima, Taku T.; Ikeda, Akihiko; Matsuda, Yasuhiro H. Journal of the Physical Society of Japan, Vol. 86, Issue 5 https://doi.org/10.7566/JPSJ.86.054710	journal	May 2017
Skyrme Insulators: Insulators at the Brink of Superconductivity Erten, Onur; Chang, Po-Yao; Coleman, Piers Physical Review Letters, Vol. 119, Issue 5 https://doi.org/10.1103/PhysRevLett.119.057603	journal	August 2017
Kondo lattice effects and the collapse of lattice coherence in Yb 1 − x Lu x B 12 studied by hard x-ray photoelectron spectroscopy Yamaguchi, J.; Sekiyama, A.; Imada, S. Physical Review B, Vol. 79, Issue 12 https://doi.org/10.1103/PhysRevB.79.125121	journal	March 2009
AC measurement of heat capacity and magnetocaloric effect for pulsed magnetic fields Kohama, Yoshimitsu; Marcenat, Christophe; Klein, Thierry Review of Scientific Instruments, Vol. 81, Issue 10 https://doi.org/10.1063/1.3475155	journal	October 2010
Fermi surface in the absence of a Fermi liquid in the Kondo insulator SmB6 Hartstein, M.; Toews, W. H.; Hsu, Y. -T. Nature Physics, Vol. 14, Issue 2 https://doi.org/10.1038/nphys4295	journal	October 2017
Excitons in topological Kondo insulators: Theory of thermodynamic and transport anomalies in SmB$_{6}$ Knolle, Johannes; Cooper, Nigel Apollo - University of Cambridge Repository https://doi.org/10.17863/cam.9232	text	January 2017
Topological Kondo Insulators Dzero, Maxim; Xia, Jing; Galitski, Victor Annual Review of Condensed Matter Physics, Vol. 7, Issue 1 https://doi.org/10.1146/annurev-conmatphys-031214-014749	journal	March 2016
Theory of Thermal Hall Effect in Quantum Magnets Katsura, Hosho; Nagaosa, Naoto; Lee, Patrick A. arXiv https://doi.org/10.48550/arxiv.0904.3427	text	January 2009
Topological Crystalline Kondo Insulator in Mixed Valence Ytterbium Borides Weng, Hongming; Zhao, Jianzhou; Wang, Zhijun arXiv https://doi.org/10.48550/arxiv.1308.5607	text	January 2013
Quantum oscillations without a Fermi surface and the anomalous de Haas-van Alphen effect Knolle, Johannes; Cooper, Nigel R. arXiv https://doi.org/10.48550/arxiv.1507.00885	text	January 2015
Unconventional Fermi surface in an insulating state Tan, B. S.; Hsu, Y. -T.; Zeng, B. arXiv https://doi.org/10.48550/arxiv.1507.01129	text	January 2015
Skyrme insulators: insulators at the brink of superconductivity Erten, Onur; Chang, Po-Yao; Coleman, Piers arXiv https://doi.org/10.48550/arxiv.1701.06582	text	January 2017
Bulk and surface electronic properties of SmB6: a hard x-ray photoelectron spectroscopy study Utsumi, Y.; Kasinathan, D.; Ko, K-T. arXiv https://doi.org/10.48550/arxiv.1705.03459	text	January 2017
Quantum Oscillation from In-gap States and non-Hermitian Landau Level Problem Shen, Huitao; Fu, Liang arXiv https://doi.org/10.48550/arxiv.1802.03023	text	January 2018
Non-Hermitian perspective of the band structure in heavy-fermion systems Yoshida, Tsuneya; Peters, Robert; Kawakami, Norio arXiv https://doi.org/10.48550/arxiv.1805.01172	text	January 2018
Quantum Oscillations of Electrical Resistivity in an Insulator Xiang, Z.; Kasahara, Y.; Asaba, T. arXiv https://doi.org/10.48550/arxiv.1905.05140	text	January 2019
Nodal Structure of Unconventional Superconductors Probed by the Angle Resolved Thermal Transport Measurements Matsuda, Y.; Izawa, K.; Vekhter, I. arXiv https://doi.org/10.48550/arxiv.cond-mat/0611371	text	January 2006
Specific heat measurements of the gap structure of the organic superconductors kappa-(ET)_2Cu[N(CN)_2]Br and kappa-(ET)_2Cu(NCS)_2 Taylor, O. J.; Carrington, A.; Schlueter, J. A. arXiv https://doi.org/10.48550/arxiv.cond-mat/0703673	text	January 2007
Topological Kondo Insulators Dzero, Maxim; Xia, Jing; Galitski, Victor Annual Review of Condensed Matter Physics, Vol. 7, Issue 1 https://doi.org/10.1146/annurev-conmatphys-031214-014749	journal	March 2016
Quantum oscillations without a Fermi surface and the anomalous de Haas-van Alphen effect Knolle, Johannes; Cooper, Nigel R. arXiv https://doi.org/10.48550/arxiv.1507.00885	text	January 2015
Quantum oscillations in insulators with neutral Fermi surfaces Sodemann, Inti; Chowdhury, Debanjan; Senthil, T. arXiv https://doi.org/10.48550/arxiv.1708.06354	text	January 2017
Evidence for short-range antiferromagnetic fluctuations in Kondo-insulating YbB12 Mignot, J. -M.; Alekseev, P. A.; Nemkovski, K. S. arXiv https://doi.org/10.48550/arxiv.cond-mat/0503142	text	January 2005

Similar Records

Unusual high-field metal in a Kondo insulator

Journal Article · 2021 · Nature Physics · OSTI ID:1867172

Xiang, Ziji; Chen, Lu; Chen, Kuan-Wen; +11 more

Charge-neutral fermions and magnetic field-driven instability in insulating YbIr₃Si₇

Journal Article · 2022 · Nature Communications · OSTI ID:1904321

Sato, Y.; Suetsugu, S.; Tominaga, T.; +11 more

Transition between heavy-fermion strange metal and quantum spin liquid in a 4d-electron trimer lattice

Journal Article · 2024 · Physical Review Letters · OSTI ID:2339591

Zhao, Hengdi; Zhang, Yu; Schlottmann, Pedro; +3 more

Related Subjects

36 MATERIALS SCIENCE
High magnetic field science
Electronic properties and materials

Title: Unconventional thermal metallic state of charge-neutral fermions in an insulator

Citation Formats

References (61)

Similar Records

Related Subjects