Studies on strain relaxation and in-plane orientation of La0.7Ca0.3MnO3 film by grazing incidence X-ray diffraction

Abstract

Perovskite manganite La0.7Ca0.3MnO3 (LCMO) films were deposited on (0 0 1)-oriented single crystal MgO and SrTiO3 (STO) substrates by 90° off-axis radio frequency magnetron sputtering. The thickness of LCMO/STO film was 50 nm. The thickness of LCMO/MgO films ranged from 5 nm to 200 nm. LCMO films were well (0 0 1)-oriented grown with high crystalline quality. Grazing incidence X-ray diffraction technique and normal X-ray diffraction were applied to characterize the in-plane and out-of-plane lattice strains and strain relaxation. The in-plane growth orientations of LCMO films with respect to substrate surface were also studied. The results indicated that the lattice strain of LCMO films began to relax when the film thickness is less than 5 nm. The mechanism for strain relaxation in LCMO films is perhaps different from that for tetragonal distortion. The in-plane growth orientation of LCMO/MgO film studied by grazing incidence X-ray diffraction technique is consistent with that from transmission electron microscopy.