Yu-Shiba-Russinov states around an excess iron in FeSe<sub>0.4</sub>Te<sub>0.6</sub>

ORAL

Abstract

Zero-energy bound states have been detected at interstitial excess irons in the iron-based superconductor Fe(Se,Te) by using a scanning tunneling microscope (STM) [1], and its relationship to the Majorana quasiparticles (QP) has been discussed [2]. However, higher energy resolution of the order of ~10 μeV is necessary to make clear the origin of the bound states at the excess irons.
Here, we performed high-energy resolution (~20 μeV) tunneling spectroscopy around excess irons, using a dilution-refrigerator STM [3]. We found that most of the excess irons indicate only finite energy peaks. We also found excess irons with the zero energy peak, but it splits into a pair of finite energy peaks with increasing the distance from the excess irons and with changing the set-point conductance. These findings suggest that the bound states at the excess irons are not Majorana QP in origin but associated with the conventional Yu-Shiba-Russinov state.

[1] J-X. Yin et al., Nat. Phys. 11, 543 (2015).
[2] K. Jiang et al., Phys. Rev. X 9, 011033 (2019)
[3] T. Machida et al., Rev. Sci. Instrum. 89, 0930707 (2018).

*This work was partly supported by CREST Project No. JPMJCR16F2 and PREST project No. JPMJPR19L8 from JST.

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Presenters

  • Tadashi Machida

    • RIKEN
    • RIKEN CEMS

Authors

  • Tadashi Machida

    • RIKEN
    • RIKEN CEMS

  • Yue Sun

    • Department of Physics and Mathematics, Aoyama Gakuin University

  • Sunseng Pyon

    • Department of Applied Physics, The University of Tokyo
    • University of Tokyo

  • Shun Takeda

    • Laboratory for Materials and Structures, Tokyo Institute of Technology

  • Yuhki Kohsaka

    • RIKEN

  • Tetsuo Hanaguri

    • Center for Emergent Matter Science, RIKEN
    • RIKEN
    • CEMS, RIKEN
    • RIKEN CEMS

  • Takao Sasagawa

    • Tokyo Inst. of Tech.
    • Laboratory for Materials and Structures, Tokyo Institute of Technology

  • Tsuyoshi Tamegai

    • Department of Applied Physics, The University of Tokyo
    • Department of Applied Physics, University of Tokyo