We present muon spin rotation and relaxation $\left(\mu \mathrm{SR}\right)$ measurements as well as demagnetizing-field-corrected magnetization measurements on polycrystalline samples of the noncentrosymmetric superconductor BeAu. From $\mu \mathrm{SR}$ measurements in a transverse field, we determine that BeAu is a type-I superconductor with H${}_c=$ 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 $\mu \mathrm{SR}$ measurements. Using both types of measurements, we construct a phase diagram from $T=30$ mK to $T_c\approx 3.25$ K. We then study the effect of hydrostatic pressure and find that 450 MPa decreases T${}_c$ 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.

• Received 31 January 2019

DOI:https://doi.org/10.1103/PhysRevB.99.134510