Response of the electric resistance of 40-nm-thick La0.67Ca0.33MnO3 films to an increase in the lattice mismatch between film and substrate

Abstract

We have studied the structure and resistivity of 40-nm-thick La0.67Ca0.33MnO3 (LCMO) films coherently grown on (001)-oriented La0.29Sr0.71Al0.65Ta0.35O3 single crystal substrates bearing epitaxial interlayers of strontium titanate with a thickness of 7 or 70 nm. As the effective mismatch between the crystal lattice parameters of the film and substrate increases, the ρ value exhibits a sharp growth, while the maximum of the ρ(T) curve shifts by ∼40 K toward lower temperatures. At T < 150 K, the temperature dependence of the resistivity of the LCMO films obeys the relation ρ ∼ ρ1 T 4.5, where the coefficient ρ1 decreases with increasing applied magnetic field strength and with decreasing lattice mismatch between the manganite film and the substrate.