Effect of hydrostatic pressure on electrical resistivity of La0.5Ca0.5Mn1-xMoxO3 (x = 0.03 and 0.05) manganites: Experimental and Theoretical approaches

Abstract Temperature-dependent electrical resistivity [ρ(T)] of Mn site doped La0.5Ca0.5Mn1-xMoxO3 (x = 0.03 and 0.05) manganites are measured under various hydrostatic pressures. At ambient pressure, x = 0.03 and 0.05 samples exhibit insulating to metallic transition (TIM) at 72 K (81 K) and 89 K (101 K) during cooling (warming) cycles. The differences between TIM’s of cooling and warming cycles shows hysteresis in ρ(T), and suggests the presence of first-order transition in both samples. The application of external pressure reduces the magnitude of resistivity, whereas it increases TIM of both samples. At the same time, the width of the hysteresis has reduced by the pressure, and get suppressed at 2.65 GPa and 2.54 GPa for 0.03 and 0.05 samples respectively. It indicates the change of first-order to second-order phase transition under pressure in both samples. ρ(T) under various pressures are separately analyzed with respect to TIM. In the insulating region (above TIM), pressure reduces the activation energy but increases the density of states at the Fermi level. In the metallic region (below TIM), pressure reduces various scattering factors between subatomic particles. Hence, metallicity of both samples is enhanced under pressure. First principles calculations are performed with various pressure region, and this study validates the experimental observation of pressure-enhanced conductivity in La0.5Ca0.5Mn1-xMoxO3 (x = 0.03 and 0.05) systems.