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

Abstract Enhancing spin-to-charge (S <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo stretchy="false">→</mml:mo> </mml:mrow> </mml:math> 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo stretchy="false">→</mml:mo> </mml:mrow> </mml:math> C efficiency. On one hand, we analyze strains-induced magnetic anisotropies in yttrium iron garnet (Y 3 Fe 5 O 12 , YIG) by comparing the magnetic and structural properties of YIG films grown on Gd 3 Ga 5 O 12 (GGG) and (CaGd) 3 (MgZrGa) 5 O 12 (SGGG) substrates. Differences in lattice mismatch—YIG//GGG ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>η</mml:mi> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>0.06</mml:mn> </mml:mrow> </mml:math> %) and YIG//SGGG ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>η</mml:mi> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>0.83</mml:mn> </mml:mrow> </mml:math> %)—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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo stretchy="false">→</mml:mo> </mml:mrow> </mml:math> C conversion, providing insight into the design of efficient spintronic devices.