Nematic superconductivity in the topological semimetal CaSn$_{3}$

H. Siddiquee; R. Munir; C. Dissanayake; P. Vaidya; C. Nickle; E. Del Barco; G. Lamura; C. Baines; S. Cahen; C. Hérold; P. Gentile; T. Shiroka; Y. Nakajima

doi:10.1103/physrevb.105.094508

arXiv · 1901.02087

Nematic superconductivity in the topological semimetal CaSn$_{3}$

H. Siddiquee·R. Munir·C. Dissanayake·P. Vaidya·C. Nickle·E. Del Barco·G. Lamura·C. Baines·S. Cahen·C. Hérold·P. Gentile·T. Shiroka·Y. Nakajima

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Abstract

The superconducting behavior of the topological semimetal CaSn$_{3}$ was investigated by means of magnetotransport and muon spectroscopy $μ$SR measurements, both providing strong evidence of nematic behavior. Magnetotransport detects an anisotropic upper critical field, characterized by a twofold symmetry about $C_{4}$ axis, thus breaking the rotational symmetry of the underlying cubic lattice. Transverse-field $μ$SR data support such picture, with the muon depolarization rate depending strongly on the magnetic field direction, here applied along the [110] or [001] crystal directions. In the former case, the absence of any additional muon depolarization suggests an unconventional vortex lattice. In the latter case, a vortex lattice encompassing a sample volume of at least 52% indicates the bulk nature of CaSn$_{3}$ superconductivity. The resulting superfluid density in the (001) planes shows a gapped low-temperature behavior, with a superconducting gap value $Δ(0)\simeq 0.61(7)$ meV. Additional zero-field $μ$SR results indicate that the superconducting state is time-reversal-invariant. This fact and the breaking of rotational symmetry in a fully-gapped superconductor are consistent with an unconventional pairing state in a multi-dimensional representation, thus making CaSn$_{3}$ an important example of nematic superconductor.

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H. Siddiquee, R. Munir, C. Dissanayake, P. Vaidya, C. Nickle, E. Del Barco, G. Lamura, C. Baines, S. Cahen, C. Hérold, P. Gentile, T. Shiroka, Y. Nakajima. 2022-03-18. Nematic superconductivity in the topological semimetal CaSn$_{3}$. https://doi.org/10.1103/physrevb.105.094508

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