Pressure effects on charge, spin, and metal-insulator transitions in narrow bandwidth manganite Pr$_{1-x}$Ca$_{x}$MnO$_{3}$

TL;DR

This study investigates how pressure influences charge, spin, and metal-insulator transitions in Pr$_{1-x}$Ca$_{x}$MnO$_{3}$, revealing pressure-induced ferromagnetic metallic states and complex coupling behaviors between transition temperatures.

Contribution

It provides new insights into pressure-induced phase transitions and the coupling between magnetic and electronic states in narrow bandwidth manganites.

Findings

Pressure suppresses charge ordering and induces ferromagnetic metallic states.

Metal-insulator transition temperature (T$_{MI}$) varies non-monotonically with pressure.

Coupling between T$_{MI}$ and T$_{C}$ depends on doping level and pressure range.

Abstract

Pressure effects on the charge and spin states and the relation between the ferromagnetic and metallic states were explored on the small bandwidth manganite Pr$_{1-x}$Ca$_{x}$MnO$_{3}$ (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 (T$_{MI}$) increases with pressure below a critical point P*, above which T$_{MI}$ decreases and the material becomes insulating as at the ambient pressure. The e$_{g}$ 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 T$_{MI}$ and Curie temperature (T$_{C}$) change with pressure in a reverse way and do not couple under pressure. In the x = 0.3 compound, the relation of T$_{MI}$ and T$_{C}$ shows a critical behavior: They are coupled in the range of $\sim$0.8-5 GPa and decoupled outside of this range. In the x = 0.35 compound, T$_{MI}$ and T$_{C}$ are coupled in the measured pressure range where a ferromagnetic state is present.