Resonance spin-charge phenomena and mechanism of magnetoresistance anisotropy in manganite/metal bilayer structures

The dc voltage generated under ferromagnetic resonance has been studied in bilayer structures based on manganite thin epitaxial films La0.67Sr0.33MnO3 (LSMO) and non-magnetic metals (Au, Pt, and SrRuO3) in the temperature range up to the Curie point. The effect is shown to be caused by two different phenomena: (1) the resonance dc electromotive force related to anisotropic magnetoresistance (AMR) in the manganite film and (2) pure spin current (spin pumping) registered by means of the inverse spin Hall effect in normal metal. The two phenomena were separated using the angular dependence of the effect, the external magnetic field H0 being rotated in the film plane. It was found that the AMR mechanism in the manganite films differs substantially from that in traditional ferromagnetic metals being governed by the colossal magnetoresistance together with the in-plane magnetic anisotropy. The spin pumping effect registered in the bilayers was found to be much lower than that reported for common ferromagnets; possible reasons are discussed.