Pressure effects on charge, spin, and metal-insulator transitions in narrow bandwidth manganite Pr₁₋ₓCaₓMnO₃

Original · EN

Pressure effects on the charge and spin states and the relation between the ferromagnetic and metallic states were explored on the small bandwidth manganite Pr₁₋ₓCaₓMnO₃ (x = 0.25, 0.3, 0.35). Under pressure, the charge ordering state is suppressed and a ferromagnetic metallic state is induced in all three samples. The metal-insulator transition temperature (TMI) increases with pressure below a critical point P*, above which TMI decreases and the material becomes insulating as at the ambient pressure. The eg electron bandwidth and/or band-filling mediate the pressure effects on the metal-insulator transition and the magnetic transition. In the small bandwidth and low doping concentration compound (x = 0.25), the TMI and Curie temperature (TC) change with pressure in a reverse way and do not couple under pressure. In the x = 0.3 compound, the relation of TMI and TC shows a critical behavior: They are coupled in the range of 0.8-5 GPa and decoupled outside of this range. In the x = 0.35 compound, TMI and TC are coupled in the measured pressure range where a ferromagnetic state is present.