Effect of Hydrostatic Pressure on the Resistivity of La 0.8 Ag 0.1 MnO 3 Ceramic near T C

The effect of hydrostatic pressure up to 8.5 GPa on the transport characteristics of granular ceramic manganite La 0.8 Ag 0.1 MnO 3 near the temperature corresponding to the magnetoresistance peak has been studied. The electrical resistivity has been measured in the temperature range of 275–320 K at pressures P = 0, 0.44, 2.32, 3.81, and 4.84 GPa. The temperature of the transition from the metallic to semiconductor type of conductivity is a monotonically increasing function of the applied pressure with a slope of 4.54 K/GPa. At 296 K, the linear logarithmic plot of the pressure dependence of the resistivity exhibits an anomaly in the form of a kink at 3.85 GPa. It has been shown that the observed transition with a change in the slope in the logarithmic plot of the pressure dependence of the resistivity is due to the existence of two scattering processes: intragranular and near-boundary ones. Near the transition point, both scattering processes make comparable contributions to the resistivity. For pressures P < 3.85 GPa, the contribution to the resistivity from scattering in the boundary layers of grains dominates, whereas the contribution from the homogeneous material within the grains is dominant in the high-pressure range.