Time-Reversal Symmetry Breaking Superconductivity in CaSb$_2$
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arXiv
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2023
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| _version_ | 1866913369631490048 |
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| author | Oudah, M. Cai, Y. Sanchez, M. V. De Toro Bannies, J. Aronson, M. C. Kojima, K. M. Bonn, D. A. |
| author_facet | Oudah, M. Cai, Y. Sanchez, M. V. De Toro Bannies, J. Aronson, M. C. Kojima, K. M. Bonn, D. A. |
| contents | CaSb$_2$ is a bulk superconductor and a topological semimetal, making it a great platform for realizing topological superconductivity. In this work, we investigate the superconducting upper and lower critical field anisotropy using magnetic susceptibility, and study the superconducting state using muon spin-relaxation. The temperature dependence of transverse-field relaxation rate can be fitted with a single-gap model or two-gap model. Zero-field relaxation shows little temperature dependence when the muon-spin is parallel to the $c*$-axis, while an increase in relaxation appears below 1 K when the muon-spin is parallel to the $ab$-plane. We conclude an $s+is$ order parameter considering the breaking of time-reversal symmetry (TRS), which originates from competing interband interactions between the three bands of CaSb$_2$. To explain the direction-dependent breaking of TRS we suggest loop currents developing in the plane of distorted square-net of Sb atoms. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2309_12457 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Time-Reversal Symmetry Breaking Superconductivity in CaSb$_2$ Oudah, M. Cai, Y. Sanchez, M. V. De Toro Bannies, J. Aronson, M. C. Kojima, K. M. Bonn, D. A. Superconductivity Materials Science CaSb$_2$ is a bulk superconductor and a topological semimetal, making it a great platform for realizing topological superconductivity. In this work, we investigate the superconducting upper and lower critical field anisotropy using magnetic susceptibility, and study the superconducting state using muon spin-relaxation. The temperature dependence of transverse-field relaxation rate can be fitted with a single-gap model or two-gap model. Zero-field relaxation shows little temperature dependence when the muon-spin is parallel to the $c*$-axis, while an increase in relaxation appears below 1 K when the muon-spin is parallel to the $ab$-plane. We conclude an $s+is$ order parameter considering the breaking of time-reversal symmetry (TRS), which originates from competing interband interactions between the three bands of CaSb$_2$. To explain the direction-dependent breaking of TRS we suggest loop currents developing in the plane of distorted square-net of Sb atoms. |
| title | Time-Reversal Symmetry Breaking Superconductivity in CaSb$_2$ |
| topic | Superconductivity Materials Science |
| url | https://arxiv.org/abs/2309.12457 |