Self-induced spin-to-charge conversion in single FePt films

AMPUERO TORRES, J.L.; AVILÉS FÉLIX, L.; JAVIER E. GÓMEZ; A. ANADON; H. DAMAS; S. PETIT WAVELOT; J.-C. ROJAS SÁNCHEZ; ALEJANDRO BUTERA

Workshop; International workshop on Spintronics 2022; 2022

Centro Atómico Bariloche

Self-induced inverse spin Hall effect and self-induced spin-orbit torque in single ferromagnetic films have been object of interest over the last years. [1,2] Ferromagnets such as Co, Fe or Permalloy have shown spin-to-charge current conversion in resonance condition with efficiencies similar to non-magnetic metals such as Pt or Ta; however, the origin and understanding of this effect is still under debate. In this work, we present a systematic study of the self-induced inverse spin Hall effect (ISHE) in single FePt films with thicknesses ranging from 5 nm to 25 nm. FePt films were grown on Si(100) substrates by DC magnetron sputtering at room temperature from a target with atomic concentration 50:50 in an argon atmosphere. All deposited films grew in the magnetically soft metastable A1 phase. Spin pumping/inverse spin Hall effect experiments, performed at 9.5 GHz in a rectangular TE102 resonator, revealed that the dominant component in the induced Vdc signal is mostly symmetric and changes its sign (preserving the amplitude) upon inversion of the applied magnetic field, which is an indication that spin-charge conversion is mainly produced by ISHE and other effects such as AMR or AHE are negligible. Measurements of frequency dependent ferromagnetic resonance for the different thickness showed a damping constant ~10-2 which decreases as the effective field (Heff) increases with film thickness. Saturation magnetization dependence with FePt thickness indicates the presence of a magnetically disordered region, which may be at the film-substrate interface, promoting a preferential flow of spins towards the substrate. Our results aim to contribute to the understanding of spin-to-charge conversion in single ferromagnetic layers.References[1] A. Tsukahara, Y. Ando, Y. Kitamura, H. Emoto, E. Shikoh, M P Delmo, T. Shinjo and M. Shiraishi, “Self-induced inverse spin Hall effect in permalloy at room temperature” Physical Review B 89, 235317, 2014.[2] O. Gladii, L. Frangou, A. Hallal, R L Seeger, P. Noel, G. Forestier, S. Auffret, M. Rubio-Roy, P. Warin, L. Vila, S. Wimmer, H. Ebert, S. Gambarelli, M. Chshiev and V. Baltz, “Self-induced inverse spin Hall effect in ferromagnets:Demostration through nonmonotonic temperatute dependence in permalloy” Physical Review B 100, 174409, 2019.