μSR and magnetometry study of the type-I superconductor BeAu

We present muon spin rotation and relaxation (μSR) measurements as well as demagnetizing-field-corrected magnetization measurements on polycrystalline samples of the noncentrosymmetric superconductor BeAu. From μSR measurements in a transverse field, we determine that BeAu is a type-I superconductor with Hc= 258 Oe, amending the previous understanding of the compound as a type-II superconductor. To account for demagnetizing effects in magnetization measurements, we produce an ellipsoidal sample, for which a demagnetization factor can be calculated. After correcting for demagnetizing effects, our magnetization results are in agreement with our μSR measurements. Using both types of measurements, we construct a phase diagram from T=30 mK to Tc≈3.25 K. We then study the effect of hydrostatic pressure and find that 450 MPa decreases Tc by 35 mK, comparable to the change seen in the type-I elemental superconductors Sn, In, and Ta. This suggests BeAu is far from a quantum critical point accessible by the application of pressure.