Time reversal symmetry breaking and s-wave superconductivity in CaPd2Ge2: A $\mu$SR study

Abstract

$\mathrm{CaP}{\mathrm{d}}_2\mathrm{G}{\mathrm{e}}_2$ which crystallizes in $\mathrm{ThC}{\mathrm{r}}_2\mathrm{S}{\mathrm{i}}_2$-type body-centered tetragonal structure exhibits superconductivity below the critical temperature $T_{\mathrm{c}}=1.69$~K\@. We have investigated the superconducting gap structure and time reversal symmetry of the ground state in $\mathrm{CaP}{\mathrm{d}}_2\mathrm{G}{\mathrm{e}}_2$ by means of muon spin relaxation and rotation ($\mu$SR) measurements. Our analysis of $\mu$SR data collected in transverse magnetic field reveals BCS superconductivity with a single-band $s$-wave singlet pairing and an isotropic energy gap having the value $2\Delta (0)/k_{\mathrm{B}}{T}_{\mathrm{c}}=3.50(1)$. Further, an increased relaxation rate in zero field $\mu$SR asymmetry spectra below $T_{\mathrm{c}}$ provides evidence for the presence of a spontaneous magnetic field in the superconducting state revealing that the time-reversal symmetry is broken in $\mathrm{CaP}{\mathrm{d}}_2\mathrm{G}{\mathrm{e}}_2$.

8 pages, 5 figures

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Cited by in corpus (1)

• Probing the superconducting gap structure of ScRuSi via $\mu$SR and first-principles calculations