Strain-induced enhancement of spin pumping in Pt/YIG bilayers

Abstract

Enhancing spin-to-charge (S -> C) conversion efficiency remains a key challenge in spintronic materials research. In this work we investigate the effect of substrate-induced strains onto the S -> C efficiency. On one hand, we analyze strains-induced magnetic anisotropies in yttrium iron garnet (Y3Fe5O12, YIG) by comparing the magnetic and structural properties of YIG films grown on Gd3Ga5O12 (GGG) and (CaGd)3(MgZrGa)5O12 (SGGG) substrates. Differences in lattice mismatch-YIG//GGG ( eta=-0.06%) and YIG//SGGG ( eta=-0.83%)-lead to out-of-plane tensile strains in the first case and unexpected compressive strain in the latter. On the other hand, we study the spin injection efficiency on Pt/YIG bilayers evaluated by the inverse spin Hall effect (ISHE). We find that the resulting perpendicular magnetic anisotropy in YIG//SGGG, while not dominant over shape anisotropy, correlates with enhanced ISHE signals as observed in spin pumping ferromagnetic resonance and spin Seebeck effect experiments. Strain engineering proves effective in enhancing S -> C conversion, providing insight into the design of efficient spintronic devices.