Muon spin relaxation and rotation measurements on single crystals of the heavy-fermion superconductorUBe13

Abstract

We report zero-, longitudinal-, and transverse-field positive muon spin relaxation (\ensuremath{\mu}SR) measurements in single crystals of the heavy-fermion superconductor ${\mathrm{UBe}}_{13}$ $[{T}_{c}=0.83(2)\mathrm{K}].$ Our zero-field measurements provide an upper limit for any quasistatic magnetic moments in this system below 100 K of $0.001{\ensuremath{\mu}}_{B},$ consistent with previous measurements on polycrystals. From the transverse-field measurements we find a lower bound for the London penetration depth ${\ensuremath{\lambda}}_{L}=1210\mathrm{nm}.$ This value implies a lower limit for the effective mass consistent with the low-temperature specific heat.