Lattice distortion and uniaxial magnetic anisotropy in single domain epitaxial (110) films of SrRuO3

Single domain epitaxial (110) films of SrRuO3 exhibit uniaxial magnetic ani sotropy instead of the biaxial anisotropy observed in the bulk material. Th e magnetic easy axis for the film is along the orthorhombic [010] direction below T-C, and it rotates toward the [110] perpendicular direction as temp erature decreases. The [100] direction, which is also magnetically "easy" i n the bulk, becomes "hard" in the film. X-ray diffraction experiments show that this unique transformation of magnetic anisotropy is related to a dist ortion from the bulk orthorhombic lattice into a triclinic structure in the epitaxial film, such that the lattice along the [010] direction expands wh ile its [100] counterpart contracts. The distortion appears to arise from r otation and tilt of RuO6 octahedra. The finding indicates that the magnetic anisotropy in epitaxial SrRuO3 films is rooted in the crystalline anisotro py influenced by strong spin-orbit interactions. (C) 1999 American Institut e of Physics. [S0021-8979(99)75608-2].