Magnetic and electrical properties of coherently grown low-strain La0.7Ca0.3MnO3 films

Abstract La 0.7 Ca 0.3 MnO 3 films have been grown epitaxially on NdGaO 3 (1 1 0) substrates using pulsed laser deposition. Because of the very low nominal lattice mismatch with the substrate (⩽0.12%) the films are under low epitaxial stress. The microstructure has been investigated by transmission electron microscopy, atomic force microscopy and X-ray diffraction. Coherently grown films with no detectable lattice defects (by our means) have been obtained. Their magnetic and resistive properties have been studied as a function of film thickness from 2 to 165 nm. The ferromagnetic transition temperature stays near the bulk value down to about 6 nm film thickness, and the spontaneous magnetization has a large value (∼85 emu/g) for all thicknesses (excluding the 2 nm film). Magnetic hysteresis loops show in-plane anisotropy that might still have a stress-induced contribution, with a 1 1 0 easy and a [0 0 1] hard axis. The appearance of a semiconducting layer at the film surface or the interface with the substrate is discussed.