• 
  Anand, V.K.; Bhattacharyya, A.; Adroja, D. T.; Panda, K.; Biswas, P. K.; Hillier, A. D.; Lake, B.: Time-reversal symmetry breaking and s-wave superconductivity in CaPd 2Ge₂ : A μSR study. Physical Review B 108 (2023), p. 224519/1-7

10.1103/PhysRevB.108.224519
Open Access Version (available 01.01.2025)

Abstract:
CaPd2Ge2 which crystallizes in ThCr2Si2 -type body-centered tetragonal structure exhibits superconductivity below the critical temperature Tc = 1.69 K. We have investigated the superconducting gap structure and time-reversal symmetry of the ground state in CaPd2 Ge2 by means of muon spin relaxation and rotation (μSR) measurements. Our analysis of μSR data collected in a transverse magnetic field reveals BCS superconductivity with a single-band s-wave singlet pairing and an isotropic energy gap having the value 2Delta(0)/kBTc = 3.50(1). Further, an increased relaxation rate in zero-field μSR asymmetry spectra below Tc provides evidence for the presence of a spontaneous magnetic field in the superconducting state, revealing that the time-reversal symmetry is broken in CaPd2Ge2 .