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  • Letter
  • Open Access

Time-reversal symmetry breaking superconductivity in three-dimensional Dirac semimetallic silicides

Sudeep K. Ghosh1,*,†, P. K. Biswas2,*, Chunqiang Xu3,4, B. Li5, J. Z. Zhao6, A. D. Hillier2,‡, and Xiaofeng Xu3,§

  • 1School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
  • 2ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
  • 3Key Laboratory of Quantum Precision Measurement of Zhejiang Province, Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023, China
  • 4School of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China
  • 5Information Physics Research Center, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
  • 6Co-Innovation Center for New Energetic Materials, Southwest University of Science and Technology, Mianyang 621010, China

  • *These authors contributed equally to this work.
  • †S.Ghosh@kent.ac.uk
  • ‡adrian.hillier@stfc.ac.uk
  • §xuxiaofeng@zjut.edu.cn
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Phys. Rev. Research 4, L012031 – Published 15 March, 2022

DOI: https://doi.org/10.1103/PhysRevResearch.4.L012031

Abstract

Superconductors with broken time-reversal symmetry represent arguably one of the most promising venues for realizing highly sought-after topological superconductivity that is vital to fault-tolerant quantum computation. Here, by using extensive muon-spin relaxation and rotation measurements, we report that the isostructural silicide superconductors (Ta, Nb)OsSi spontaneously break time-reversal symmetry at the superconducting transition while surprisingly showing a fully gapped superconductivity characteristic of conventional superconductors. The first-principles calculations show that (Ta, Nb)OsSi are three-dimensional Dirac semimetals protected by nonsymmorphic symmetries. Taking advantage of the exceptional low symmetry crystal structure of these materials, we have performed detailed theoretical calculations to establish that the superconducting ground state for both (Ta, Nb)OsSi is most likely a nonunitary triplet state.

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      Supplemental Material

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      Phys. Rev. Research 4, L012031– Published 15 March, 2022
      • Received 8 December 2021
      • Revised 11 February 2022
      • Accepted 27 February 2022
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      Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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