Magnetic anisotropy of (100)- and (110)-oriented epitaxial CrO2 films grown on SnO2- the effects of strain and interface

Abstract The crystal structures and magnetic properties of CrO 2 films of different orientations and thicknesses grown on SnO 2 were investigated and compared with those on TiO 2 . Results reveal that large anisotropic strains were found in (100) films, but only small strains existed in (110) films. The magnetic anisotropies of CrO 2 (110) films on SnO 2 and TiO 2 were found to be similar. As for CrO 2 (100) films, magnetic anisotropies were quite different-at the same thickness, the magnetic anisotropy of the film on SnO 2 substrate was higher than that on TiO 2 . However, the easy axes of the films were found to be always along c axis even at very small thickness, and no easy axis switching was observed. First-principle calculations reveal that magnetic anisotropy energy is not only concerned with anisotropic strain but also with the substrate. The competition between the anisotropic preference of interface and the effect of strains may be one important factor for determining the actual easy axis direction. The combined effects of strain and interface may also be one reason for the magnetic anisotropic difference between CrO 2 (100) films on SnO 2 and TiO 2 .