Papers by Author: M. Varela

Abstract: Magnetotransport properties of very high quality fully strained epitaxial thin films of La2/3Ca1/3MnO3 (LCMO), grown on top of SrTiO3 (STO) (001) substrates, are analyzed. As-grown fully strained epitaxial films are ferromagnetic and metallic but exhibit depressed transport and magnetic properties (low TC and MS). Detailed analysis of the structural and magnetotransport properties after high temperature annealing processes, have revealed a progressive structural relaxation, as detected by the variation of the c/a tetragonal distortion, as the annealing temperature rises up. Nevertheless, no changes in the in-plane cell parameters are observed. Simultaneously, the magnetic transition temperature, TC, and saturation magnetisation, MS, substantially increase approaching values similar to that of bulk materials.

Abstract: We report here on the growth of epitaxial YMnO3 thin films on SrTiO3 single crystalline substrates. We show that depending of the choice of the substrate orientation or use of suitable (metallic) buffer layer, the epitaxial texture of the YMnO3 thin films as well as its crystallographic phase (orthorhombic or hexagonal) can be selected. Antiferromagnetic YMnO3 films have been also grown on ferromagnetic SrRuO3 epitaxial layers. Magnetic measurements show the existence of an exchange bias in orthorhombic films.