Catastrophic Fermi surface reconstruction in the shape-memory alloy AuZn

AuZn undergoes a shape-memory transition at 67~K. An abrupt change in the quantum oscillations is observed at this temperature, indicating a disintegration of the Fermi surface associated with the transition. The de Haas-van Alphen effect is measured above and below the transition, at temperatures up to 100~K, and is in reasonable agreement with band-structure calculations in both the high and low-temperature phases. The measurements are strongly suggestive of an inherent, bulk phase separation at low temperatures. In addition, a Dingle analysis reveals a sharp change in the scattering mechanism at a certain cyclotron radius. Both these observations are indicative of the characteristic microstructure that drives the shape-memory effect.