μSR study of the noncentrosymmetric superconductor PbTaSe2

We present muon spin rotation and relaxation (μSR) measurements on the noncentrosymmetric superconductor PbTaSe2. From measurements in an applied transverse field between Hc1 and Hc2, we extract the superfluid density as a function of temperature in the vortex state. These data can be fit with a fully gapped two-band model, consistent with previous evidence from ARPES, thermal conductivity, and resistivity. Furthermore, zero-field measurements show no evidence for a time-reversal symmetry-breaking field greater than 0.05 G in the superconducting state. This makes exotic fully gapped spin-triplet states unlikely, and hence we contend that PbTaSe2 is characterized by conventional BCS s-wave superconductivity in multiple bands.