Pressure dependence of resistivity and magnetoresistance in Pr-doped La0.7Ca0.3MnO3

Abstract

We report the effects of magnetic field (μ0H 0-7 T) and hydrostatic pressure (P 1 bar to 9.53 kbar) on electrical resistivity in the phase separated manganite La0.3Pr0.4Ca 0.3MnO3. The resistivity shows a first-order transition from paramagnetic insulating to ferromagnetic metallic state at a temperature T TIM in ambient pressure and zero magnetic field. The first-order transition becomes second-order with increasing pressure and/or magnetic field. Both hydrostatic pressure and magnetic field decrease the magnitude resistivity and shift the resistivity peak at T TIM towards high temperature with different rates (dTIM/dH 13.5 K/T for P 1 bar, 8.8 K/T for P 9.53 kbar, and dTIM/dP ∼ 4.42 K/kbar in zero field). However, the magnitude of the magnetoresistance decreases with increasing pressure. Baroresistance in the absence of magnetic field for ΔP 9.53 kbar reaches nearly 100 around 150 K. Interestingly, while the resistivity at a constant temperature shows irreversible behaviour upon cycling the direction of magnetic field at ambient pressure, the irreversibility is eliminated under hydrostatic pressure. Our results indicate that pressure eliminates phase separation by converting the paramagnetic polaronic phase into ferromagnetic metallic phase in the vicinity of phase coexistence. © 2013 AIP Publishing LLC.