Aspects of “low field” magnetotransport in epitaxial thin films of the ferromagnetic metallic oxide SrRuO3

Abstract Epitaxial thin films of the conductive ferromagnetic oxide SrRuO 3 were grown on an (0 0 1) SrTiO 3 (STO) substrate by using DC sputtering technique. The magnetic and magnetoresistive properties of the films were measured by applying the magnetic field both perpendicular (out-of-plane) and parallel (in-plane) to the film plane and ever maintaining the direction of the applied field perpendicular to that of the transport current. The films grown on an (0 0 1) STO substrate showed identical magnetization properties in two orthogonal crystallographic directions of the substrate, [1 0 0] S and [0 0 1] S (in-plane and out-of-plane geometry), which suggests the presence of a multi domain structure within the plane of the film. For such samples, no anisotropic field (hard axis) along de [0 0 1]s direction, i.e., perpendicular to the film-plane could be detected. Nevertheless, a distinguishable temperature dependent out-of-plane anisotropic magnetoresistance (MR) along with strong temperature dependent low field hysteretic MR( H ) behavior was detected for the studied films. A negative MR ratio MR( T )=[ ρ (μ 0 H =9 T; T )− ρ ( μ 0 H =0 T; T )]/ ρ ( μ 0 H =0 T; T ) on the order of a few percent, with maximums of ∼6% and ∼4% (right at the Curie temperature, T C ∼160 K) was calculated for an in-plane and out-of plane measuring geometry, respectively. In addition there is an equally strong MR effect at low temperatures, which might be related to the temperature dependence of the magnetocrystalline anisotropy together with a magnetization rotation. Both the MR( T ) behavior and the achieved values (except for T 3 films grown on 2° miscut (0 0 1) STO substrates with the current parallel to the field and parallel to the [ 1 ¯ 1 1 ] direction, which was identified as the easier axis for magnetization.