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 ρ, magnetoresistance $(ΔR/R0),$ and phase transition temperatures in ceramic and thin-film samples of the lanthanum manganite $La0.9Mn1.1O3±δ$ 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 $Tms$ of the metal-semiconductor phase transition and $Tp$ 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 ρ and $Tms$ on $P$ suggests that lanthanum manganite ceramics and films could be used as pressure and temperature sensors.