Valence instability of cerium under pressure in the Kondo-like perovskiteLa0.1Ce0.4Sr0.5MnO3

Abstract

The effects of hydrostatic pressure and magnetic field on the electrical resistance of the Kondo-like perovskite manganese oxide, La0.1Ce0.4Sr0.5MnO3 with a ferrimagnetic ground state, have been investigated up to 2.1GPa and 9T . In this compound, the Mn moments undergo a double exchange mediated ferromagnetic ordering at TC˜280K and there is a resistance maximum, Tmax at about 130K , which is correlated with an antiferromagnetic ordering of cerium with respect to the Mn-sublattice moments. Under pressure, the Tmax shifts to lower temperatures at a rate of dTmax/dP=-162K/GPa and disappears at a critical pressure Pc˜0.9GPa . Further, the coefficient, m of -lnT term due to Kondo scattering decreases linearly with increase of pressure showing an inflection point in the vicinity of Pc . These results suggest that cerium undergoes a transition from Ce3+ state to a Ce4+/Ce3+ mixed valence state under pressure. In contrast to the pressure effect, the applied magnetic field shifts Tmax to higher temperatures, presumably due to enhanced ferromagnetic Mn moments.