Highly mobile gapless excitations in a spin liquid state of 1T-TaS2

ORAL

Abstract

Quantum spin liquid (QSL) is a state of matter where strong quantum fluctuations destroy the long-range magnetic order even at zero temperature. In two-dimensional triangular lattice antiferromagnet, such as organic insulators, possible QSL states have been reported. However, detailed properties remain unclear due to lattice distortion and strong spin-orbit coupling.
Recently, 1T-TaS2 is proposed as an ideal material for QSL [1]. It becomes commensurate charge-dansity wave state and Mott-insulating state below 60 K, in which S=1/2 spin is localized on a center of cluster composed of 13 Ta atoms and arranged on perfect triangular lattice. NQR and μSR reveal the absence of magnetic order down to 70 mK [2].
We performed the measurements of thermal conductivity κ and specific heat C to study low-energy quasiparticle excitations. κ/T and C/T show residual term as T → 0, demonstrating the presence of gapless spin excitations. In stark contrast to organic compounds, quasiparticle mean free path is largely enhanced by applying magnetic field.
References
[1] K. T. Law, et al., PNAS 110, 6996-7000 (2017).
[2] M. Klanjsek, et al., arXiv:1704.06450v1 (2017).

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Presenters

  • Hinako Murayama

    Kyoto University

Authors

  • Hinako Murayama

    Kyoto University

  • Yuki Sato

    Kyoto University, Department of Physics, Kyoto University

  • Xiangzhuo Xing

    Kyoto University, Department of Physics, Kyoto University

  • Tomoya Taniguchi

    Kyoto University, Department of Physics, Kyoto University

  • Shigeru Kasahara

    Kyoto University, Department of Physics, Kyoto University, Kyoto Univ.

  • Yuichi Kasahara

    Department of Physics, Kyoto Univ, Kyoto University, Kyoto Univ., Department of Physics, Kyoto University

  • Masaro Yoshida

    RIKEN, RIKEN Center for Emergent Matter Science, RIKEN CEMS

  • Yoshihiro Iwasa

    Univ of Tokyo, Department of Applied Physics, The University of Tokyo, The University of Tokyo, University of Tokyo, The Univ. of Tokyo, the University of Tokyo, the Univ. of Tokyo, Univ. of Tokyo

  • Yuji Matsuda

    Department of Physics, Kyoto Univ, Kyoto University, Department of Physics, Kyoto University, Kyoto Univ.