Electrical resistivity ρ(T) of the 5f -ferromagnet UGa2 was investigated on single-crystalline samples as a function of pressure and magnetic field. Under quasihydrostatic pressure the Curie temperature monotonously increases from TC = 124 K up to 154 K at p = 14.2 GPa afterwhich it turns down steeply and reaches TC = 147 K at p = 15.2GPa. At 20 GPa the compound is already nonmagnetic. This dramatic variation is compatible with the exchange interactions mediated by the 5f hybridization with the non-f states. The external pressure first enhances the exchange coupling of the 5f moment but eventually suppresses the magnetic order by washing out the 5f moments. Such a two-band model is adequate for the weakly delocalized 5f states. The external pressure gradually suppresses the spin-disorder resistivity, which reaches very high ρ values (300 μcm) above TC in UGa2. This leads to the crossover from the initial negative to the positive dρ/dT in the paramagnetic state.

KOLOMIETS A. V.;  GRIVEAU Jean-Christophe;  PRCHAL J.;  ANDREEV A.V.;  HAVELA L; 

2015-03-02

AMER PHYSICAL SOC

JRC94732

1098-0121,   

http://arxiv.org/abs/1502.04948,    https://publications.jrc.ec.europa.eu/repository/handle/JRC94732,   

10.1103/PhysRevB.91.064405,