Variations of magnetic properties of UGa2 under pressure

TL;DR

This study investigates how applying pressure affects the magnetic and electrical properties of UGa2, revealing a non-monotonic change in Curie temperature and a transition to non-magnetic behavior at high pressures.

Contribution

It provides new insights into pressure-induced variations of magnetic properties in UGa2, highlighting the role of 5f hybridization and exchange interactions.

Findings

Curie temperature increases with pressure up to 14.2 GPa

At 20 GPa, UGa2 becomes non-magnetic

Pressure suppresses spin-disorder resistivity

Abstract

Electrical resistivity \rho(T) of the 5f ferromagnet UGa2 was investigated for single-crystal samples as a function of pressure and magnetic field. The Curie temperature monotonously increases from T$_{C}$ = 124 K under quasi-hydrostatic pressure up to 154 K at p = 14.2 GPa, after which it turns down steeply and reaches T$_{C}$ = 147 K at p = 15.2 GPa. At 20 GPa the compound is already non-magnetic. This dramatic variation is compatible with exchange interactions mediated by the 5f hybridization with the non-f states. The external pressure first enhances the exchange coupling of the 5f moments, but eventually suppresses the order by washing out the 5f moments. Such a two-band model is adequate for the weakly delocalized 5f states. The spin-disorder resistivity, which produces very high \rho-values (300 \mu\Omega.cm) is gradually suppressed by the pressure. In the paramagnetic state, this leads to a crossover from initial negative to positive d\rho/dT.