Enhancement of Spin Pumping in $\mathrm{Y_3Fe_5O_{12}/Pt/Ni_{81}Fe_{19}}$ Trilayer Film

TL;DR

This study investigates spin pumping in a YIG/Pt/NiFe trilayer, revealing unconventional voltage signals due to interactions between layers, with potential implications for spintronic device design.

Contribution

It demonstrates that simultaneous excitation of both ferromagnets leads to enhanced and sign-reversed voltages, highlighting interlayer interactions affecting spin pumping behavior.

Findings

Opposite sign voltages when ferromagnets are excited separately.

Same sign and increased magnitude when excited simultaneously.

Unconventional voltage primarily from Py/Pt interface spin pumping.

Abstract

We study spin pumping in a $\mathrm{Y_3Fe_5O_{12}(YIG)/Pt/Ni_{81}Fe_{19}(Py)}$ trilayer film by means of the inverse spin Hall effect (ISHE). When the ferromagnets are not excited simultaneously by a microwave, ISHE-induced voltage is of the opposite sign at each ferromagnetic resonance (FMR). The opposite sign is consistent with spin pumping of bilayer films. On the other hand, the voltage is of the same sign at each FMR when both the ferromagnets are excited simultaneously. Futhermore, the voltage greatly increases in magnitude. The observed voltage is unconventional; neither its sign nor magnitude can be expected from spin pumping of bilayer films. Control experiments show that the unconventional voltage is dominantly induced by spin pumping at the Py/Pt interface. Interaction between YIG and Py layers is a possible origin of the unconventional voltage.