# muSR and Magnetometry Study of the Type-I Superconductor BeAu

## TL;DR

This study uses muSR and magnetometry to establish BeAu as a type-I superconductor with a critical field of 256 Oe, and investigates its phase diagram and pressure effects, correcting previous misconceptions.

## Contribution

It provides the first muSR evidence confirming BeAu as a type-I superconductor and details its phase diagram and pressure response.

## Key findings

- BeAu is confirmed as a type-I superconductor.
- Critical field Hc = 256 Oe determined.
- Pressure of 450 MPa decreases Tc by 34 mK.

## Abstract

We present muon spin rotation and relaxation (muSR) measurements as well as demagnetising field corrected magnetisation measurements on polycrystalline samples of the noncentrosymmetric superconductor BeAu. From muSR measurements in a transverse field, we determine that BeAu is a type-I superconductor with Hc = 256 Oe, amending the previous understanding of the compound as a type-II superconductor. To account for demagnetising effects in magnetisation measurements, we produce an ellipsoidal sample, for which a demagnetisation factor can be calculated. After correcting for demagnetising effects, our magnetisation results are in agreement with our muSR 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 34 mK, comparable to the change seen in type-I elemental superconductors Sn, In and Ta, suggesting BeAu is far from a quantum critical point accessible by the application of pressure.