Influence of temperature, magnetic field, and high hydrostatic pressure on the resistivity and magnetoresistance in La0.9Mn1.1O3±δ ceramics and laser-deposited films

The influence of the magnetic field strength (H=0, 2, 4, 6, 8 kOe), high hydrostatic pressures (P=0-1.8 GPa), and temperature (T=77-300 K) on the resistivity rho, magnetoresistance (DeltaR/R-0), and phase transition temperatures in ceramic and thin-film samples of the lanthanum manganite La0.9Mn1.1O3 +/- delta is investigated by x-ray-diffraction, magnetic, and resistive methods. It is found that with increasing H and P the resistivity decreases and the temperatures T-ms of the metal-semiconductor phase transition and T-p of the magnetoresistance peak increase. The differences in the resistivities, magnetoresistances, and phase transition temperatures in the ceramics and laser-deposited films are explained by their different nonstoichiometry and defect density. The observed linear dependence of rho and T-ms on P suggests that lanthanum manganite ceramics and films could be used as pressure and temperature sensors. (C) 2001 American Institute of Physics.