Isotropic s -wave superconductivity in the noncentrosymmetric charge density wave superconductor SrPt2As2

Abstract

SrPt 2 As 2 undergoes a structural transition around 470 K (from a high-temperature tetragonal to a lowtemperature orthorhombic phase) accompanied by a charge density wave transition and followed by a superconducting transition at much lower temperature (5 K). The superconducting gap symmetry of this noncentrosymmetric compound was investigated in detail by means of muon-spin rotation or relaxation (μSR) experiments in transverse-field (TF) configuration. The temperature-dependent magnetic penetration depth obtained from the TF-μSR spectra suggests an isotropic s-wave-type superconducting gap. No observable differences are seen in the asymmetry time spectra collected in zero field above and below the superconducting transition temperature T c. This strongly suggests the absence of spontaneous magnetic fields in the superconducting state, hence pointing to a preserved time-reversal symmetry below T c .

Nodeless kagome superconductivity in LaRu3Si2

“…The observed single gap superconductivity in this multiband system implies that the superconducting pairing involves predominately one band. However, if the interband coupling is strong, then one may detect single-gap-like behavior of the superfluid density even in multigap materials [43].…”

Isotropic single gap superconductivity of elemental Pb: the `smiling' approach

“…It is worth to emphasize, that the results of bulk µSR measurement presented here may not rule out the possibility that the superconducticting response of elemental Pb changes by approaching the surface. Following predictions of the self-consistent two-gap model [50][51][52][53], even though the superconducting gaps are opened at two different Fermi surfaces, the temperature evolutions, as well as the absolute values of these gaps would stay the same in a case of strongly coupled electronic bands:…”

Isotropic single-gap superconductivity of elemental Pb

“…It is worth emphasizing that the results of bulk μSR measurement presented here may not rule out the possibility that the superconducting response of elemental Pb changes by approaching the surface. Following predictions of the self-consistent two-gap model [50][51][52][53], even though the superconducting gaps are opened at two different Fermi surfaces, the temperature evolutions, as well as the absolute values of these gaps would stay the same in a case of strongly coupled electronic bands: 1 (T ) = 2 (T ) = (T ), T c1 = T c2 = T c . Here indices 1 and 2 denote the first and the second bands, respectively.…”