Anomalous strain relief and physical properties of La0.5Ca0.5MnO3 films

Abstract

La0.5Ca0.5MnO3 films were grown using pulsed laser deposition. Several factors, such as variation of substrates, interface effects, and annealing effects, influencing the properties of the grown films were investigated. As-grown films on LaAlO3 substrates showed anomalous strain relief; they had strained and partly relaxed layers, both of which had tetragonal structures. On SrTiO3 substrates, only coherently strained layers were observed. Such a difference of growth behaviors cannot be explained solely in terms of lattice mismatch since only partly relaxed layers appeared on LaAlO3 substrates with strained SrTiO3 interlayers. Annealing treatments relieved the strains in the films, and relaxed layers were obtained after annealing. The transport and the magnetic properties of the annealed films were quite different from those of the as-grown films.