Fragile zero-energy vortex bound state in the topological superconductor candidate FeTe0.6Se0.4

ORAL

Abstract

Majorana fermions are predicted to emerge in vortex cores of topological superconductors. Although the presence of a zero-energy bound state (ZEBS) is a hallmark of the Majorana fermions, it is still controversial due to the limited energy resolution and statistics [1-4]. Using a dilution-refrigerator scanning tunneling microscope [5], we performed high-energy-resolution tunneling spectroscopy on quantum-limit vortex cores in the topological superconductor candidate FeTe0.6Se0.4. We have found that some vortices host ZEBS and others do not. The proportion of the vortices with the ZEBS decreases with the field strength, from > 80 % at 1 T to < 10 % at 6 T. This apparent fragility of the ZEBS sheds light on the relation between the ZEBS and Majorana fermions.

[1] D. Wang, et al., Science aao1797 (2018)
[2] J.-P. Xu, et al., Phys. Rev. Lett. 114, 017001 (2015)
[3] Q. Liu, et al., arXiv:1807.01278 (2018)
[4] M. Chen, et al., Nat. Commun. 9, 970 (2018)
[5] T. Machida et al., Rev. Sci. Instrum. 89, 093707 (2018)

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Presenters

  • Tadashi Machida

    Center for Emergent Matter Science, RIKEN

Authors

  • Tadashi Machida

    Center for Emergent Matter Science, RIKEN

  • Yue Sun

    Department of Physics and Mathematics, Aoyama Gakuin University

  • Sunseng Pyon

    Department of Advanced Materials, University of Tokyo, Department of Applied Physics, The University of Tokyo, University of Tokyo (Japan)

  • Shun Takeda

    Materials and Structures Laboratory, Tokyo Institute of Technology

  • Yuhki Kohsaka

    Center for Emergent Matter Science, RIKEN

  • Tetsuo Hanaguri

    Center for Emergent Matter Science, RIKEN, RIKEN CEMS

  • Takao Sasagawa

    Materials and Structures Laboratory, Tokyo Institute of Technology

  • Tsuyoshi Tamegai

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