Nodeless superconductivity in the topological nodal-line semimetal CaSb2

Abstract

CaSb2 is a topological nodal-line semimetal that becomes superconducting below 1.6 K, providing an ideal platform to investigate the interplay between topologically nontrivial electronic bands and superconductivity. In this work, we investigated the superconducting order parameter of CaSb2 by measuring its magnetic penetration depth change Δλ(T) down to 0.07 K, using a tunneling diode oscillator (TDO) based technique. Well inside the superconducting state, Δλ(T) shows an exponential activated behavior, and provides direct evidence for a nodeless superconducting gap. By analyzing the temperature dependence of the superfluid density and the electronic specific heat, we find both can be consistently described by a two-gap s-wave model, in line with the presence of multiple Fermi surfaces associated with distinct Sb sites in this compound. These results demonstrate fully-gapped superconductivity in CaSb2 and constrain the allowed pairing symmetry.

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Cited by in corpus (6)

• Intrinsic superconducting diode effects in tilted Weyl and Dirac semimetals
• Pressure evolution of the normal- and superconducting-state properties of the line-nodal material CaSb${}_2$ revealed by ${}^{123}$Sb nuclear quadrupole resonance
• Nodal-line semimetals and their variance
• Subtle Structural Anomaly under Compression in Line-Nodal CaSb${}_2$
• Determination of the London penetration depth with the tunnel diode oscillator technique
• Topological materials with extensive flat-band surface states