S-wave Superconductivity in the Dirac Line-nodal Material CaSb2

Abstract

We performed 121/123Sb-nuclear quadrupole resonance (NQR) measurements on the superconducting (SC) line-nodal material CaSb2 in order to investigate electronic properties in the normal and SC states from a microscopic point of view. In the normal state, the nuclear spin-lattice relaxation rate 1/T1 for the Sb(1) site, which is responsible for the line-nodal parts, is approximately proportional to temperature, indicating the conventional Fermi liquid state. From comparison with band structure calculations, it is considered that the NQR properties related to the line-nodal character are hidden because the conventional behavior originating from Fermi-surface parts away from the nodes is dominant. In the SC state, a clear coherence peak just below the transition temperature and an exponential decrease at lower temperatures were observed in 1/T1. These results strongly suggest that conventional s-wave superconductivity with a full gap is realized in CaSb2.

6 pages, 5 figures

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• Topologically stable gapless phases in nonsymmorphic superconductors
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Cited by in corpus (4)

• Peak in the superconducting transition temperature of the nonmagnetic topological line-nodal material CaSb${}_2$ under pressure
• Quasi-2D Fermi surface of superconducting line-nodal metal CaSb${}_2$
• Fermiology of a topological line-nodal compound CaSb2 and its implication to superconductivity: angle-resolved photoemission study
• Pressure evolution of the normal- and superconducting-state properties of the line-nodal material CaSb${}_2$ revealed by ${}^{123}$Sb nuclear quadrupole resonance