Specific heat evidence for rotational symmetry breaking in RbFe<sub>2</sub>As<sub>2</sub>

ORAL

Abstract

RbFe2As2 has the 3d5.5 electronic configuration, which corresponds to the most heavily hole-doped system among 122-type iron-based superconductors. In this system, a large mass enhancement has been observed, and the importance of the vicinity to the Mott insulator phase at 3d5 configuration has been suggested [1]. Recently, we have observed nematic fluctuations along the Fe-As direction, 45° tilted from the nematic direction usually found in other iron-based superconductors. Although the two-fold symmetry along the Fe-As direction has also been suggested from STM measurements [2], the bulk evidence for nematic ordering has not been reported. Here, we perform field-angle-resolved specific heat measurements in RbFe2As2 single crystals by using a high-resolution long-relaxation calorimeter. We choose tiny crystals of about 10 μg to avoid cancellation effect of multiple nematic domains. We find clear two-fold oscillations as a function of in-plane field angle near the superconducting transition. This provides bulk evidence for long-range nematic ordering along the Fe-As direction in RbFe2As2.
[1] L. de’ Medici et al., PRL 112, 177001 (2014).
[2] X. Liu et al., arXiv:1803.07304.

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Presenters

  • Ohei Tanaka

    • Advanced Materials Science, University of Tokyo
    • Department of Advanced Materials Science, University of Tokyo

Authors

  • Ohei Tanaka

    • Advanced Materials Science, University of Tokyo
    • Department of Advanced Materials Science, University of Tokyo

  • Yuta Mizukami

    • University of Tokyo
    • Univ of Tokyo-Kashiwanoha
    • Advanced Materials Science, University of Tokyo
    • Department of Advanced Materials Science, University of Tokyo

  • Kousuke Ishida

    • Univ of Tokyo-Kashiwanoha
    • Department of Advanced Materials Science, University of Tokyo

  • Masaya Tsujii

    • Univ of Tokyo-Kashiwanoha
    • Department of Advanced Materials Science, University of Tokyo

  • Shigeyuki Ishida

    • National Institute of Advanced Industrial Science and Technology
    • National Institute of Advanced Industrial Science and Technology)
    • AIST

  • Akira Iyo

    • National Institute of Advanced Industrial Science and Technology

  • Hiroshi Eisaki

    • National Institute of Advanced Industrial Science and Technology
    • AIST
    • National Inst. Adv. Industrial Science & Technology, Tsukuba
    • National Institute of Advanced Industrial Science and Technology)
    • Electronics and Photonics Research Institute National Institute of Advanced Industrial Science and Technology, Japan

  • Thomas Wolf

    • Karlsruhe Institute of Technology

  • Kai Grube

    • Karlsruhe Institute of Technology
    • Institute fuer Festkoerperphysik, Karlsruhe Institute of Technology

  • Hilbert loehneysen

    • Karlsruhe Institute of Technology

  • Takasada Shibauchi

    • University of Tokyo
    • Univ of Tokyo-Kashiwanoha
    • Advanced Materials Science, University of Tokyo
    • Department of Advanced Materials Science, University of Tokyo
    • Department of Advanced Material Science, University of Tokyo
    • Dept. Adv. Mat. Sci., Univ. Tokyo
    • Tokyo University