Pressure induced magnetic phase separation in La${}_{0.75}$Ca${}_{0.25}$MnO${}_3$ manganite

Abstract

The pressure dependence of the Curie temperature T${}_C(P)$ in La${}_{0.75}$Ca${}_{0.25}$MnO${}_3$ was determined by neutron diffraction up to 8 GPa, and compared with the metallization temperature T${}_{IM}(P)$ \cite{irprl}. The behavior of the two temperatures appears similar over the whole pressure range suggesting a key role of magnetic double exchange also in the pressure regime where the superexchange interaction is dominant. Coexistence of antiferromagnetic and ferromagnetic peaks at high pressure and low temperature indicates a phase separated regime which is well reproduced with a dynamical mean-field calculation for a simplified model. A new P-T phase diagram has been proposed on the basis of the whole set of experimental data.

5 pages, 4 figures