Electronic topological and structural transition inAuIn2under pressure

Electrical resistivity, thermoelectric power, and high-pressure x-ray-diffraction measurements are carried out to investigate the anomaly observed earlier in fusion data around 3 GPa in the intermetallic compound ${\mathrm{AuIn}}_2.$ While the imaging plate high-pressure angle-dispersive data indicate a structural phase transition beyond 8 GPa, the thermoelectric power shows a peak around 2 GPa, indicating the occurrence of an electronically driven isostructural transition. The first-principles linearized muffin-tin orbital calculations reveal that this transition is brought about by interception of the Fermi level by the energy-band maximum. The Lifshitz nature of this transition is responsible for the anomaly in the high-pressure electrical and fusion data.