Epitaxial strain effect in tetragonal SrRuO3 thin films

Abstract

We report on our characterization of the structural, electrical, and magnetic properties of tetragonal SrRuO3 (SRO) thin films stabilized under both compressive and tensile strain. These tetragonal films consisting of the deformed RuO6 octahedra without rotations were coherently grown on (110)ortho NdGaO3 and (110)ortho GdScO3 substrates, which provide compressive (−1.7%) and tensile (+1.0%) strains, respectively. The ferromagnetic transition temperature TC for the compressively strained film is found to be as high as 155 K, while TC of the film under tensile strain is only 100 K. The longitudinal resistivity ρxx of the compressively strained films is lower than that of the films under the tensile strain. This is attributed to the enhanced mobility for the compressive-strain case. The magnetic anisotropy also exhibits strong dependence on the substrate-induced epitaxial strain. The film under the compressive strain has the uniaxial magnetic easy axis along the out-of-plane direction, while the easy axis of the film under the tensile strain lies along the in-plane direction parallel to the [1-10]GSO one. The results demonstrate that the electrical and magnetic properties of the tetragonal SRO thin films are closely related to the RuO6 octahedral deformations due to the substrate-induced strain.