dorsal/arxiv
View SchemaObservation of Time-Reversal Symmetry Breaking in the Type-I Superconductor YbSb$_2$
| Authors | Anshu Kataria, Shashank Srivastava, Dibyendu Samanta, Pushpendra Yadav, Poulami Manna, Suhani Sharma, Priya Mishra, Joel Barker, Adrian D. Hillier, Amit Agarwal, Sudeep Kumar Ghosh, Ravi Prakash Singh |
|---|---|
| Categories | |
| ArXiv ID | 2601.07460vv1 |
| URL | https://arxiv.org/abs/2601.07460 |
| License | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
Abstract
The spontaneous breaking of time-reversal symmetry is a hallmark of unconventional superconductivity, typically observed in type-II superconductors. Here, we report evidence of time-reversal symmetry breaking in the type-I superconductor YbSb$_2$. Zero-field $\mu$SR measurements reveal spontaneous internal magnetic fields emerging just below the superconducting transition, while transverse-field $\mu$SR confirms a fully gapped type-I superconducting state. Our first-principles calculations identify YbSb$_2$ as a ${\mathbb Z}_2$ topological metal hosting a Dirac nodal line near the Fermi level. Symmetry analysis within the Ginzburg Landau framework indicates an internally antisymmetric nonunitary triplet (INT) state as the most probable superconducting ground state. Calculations based on an effective low-energy model further demonstrate that this INT state hosts gapless Majorana surface modes, establishing YbSb$_2$ as a topological superconductor. Our results highlight YbSb$_2$ as a unique material platform where type-I superconductivity coexists with triplet-pairing and nontrivial topology.
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"date_created": "2026-02-17T05:53:11.556000Z",
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"abstract": "The spontaneous breaking of time-reversal symmetry is a hallmark of unconventional superconductivity, typically observed in type-II superconductors. Here, we report evidence of time-reversal symmetry breaking in the type-I superconductor YbSb$_2$. Zero-field $\\mu$SR measurements reveal spontaneous internal magnetic fields emerging just below the superconducting transition, while transverse-field $\\mu$SR confirms a fully gapped type-I superconducting state. Our first-principles calculations identify YbSb$_2$ as a ${\\mathbb Z}_2$ topological metal hosting a Dirac nodal line near the Fermi level. Symmetry analysis within the Ginzburg Landau framework indicates an internally antisymmetric nonunitary triplet (INT) state as the most probable superconducting ground state. Calculations based on an effective low-energy model further demonstrate that this INT state hosts gapless Majorana surface modes, establishing YbSb$_2$ as a topological superconductor. Our results highlight YbSb$_2$ as a unique material platform where type-I superconductivity coexists with triplet-pairing and nontrivial topology.",
"arxiv_id": "2601.07460",
"authors": [
"Anshu Kataria",
"Shashank Srivastava",
"Dibyendu Samanta",
"Pushpendra Yadav",
"Poulami Manna",
"Suhani Sharma",
"Priya Mishra",
"Joel Barker",
"Adrian D. Hillier",
"Amit Agarwal",
"Sudeep Kumar Ghosh",
"Ravi Prakash Singh"
],
"categories": [
"cond-mat.supr-con"
],
"license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
"title": "Observation of Time-Reversal Symmetry Breaking in the Type-I Superconductor YbSb$_2$",
"url": "https://arxiv.org/abs/2601.07460",
"version": "v1"
},
"schema_id": "dorsal/arxiv",
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"variant": "snapshot-2026-01-17",
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