YIG thickness and frequency dependence of the spin-charge current conversion in YIG/Pt systems

TL;DR

This study investigates how YIG thickness influences spin-charge current conversion efficiency and frequency dependence in YIG/Pt systems, revealing optimal conditions for device applications and the role of three-magnon splitting processes.

Contribution

It provides new insights into the YIG thickness dependence of spin pumping efficiency and the frequency threshold for three-magnon splitting in YIG/Pt systems.

Findings

Thinner YIG films exhibit higher spin pumping efficiency.

Conversion factor peaks at 2.5 GHz for 1 μm YIG.

Threshold frequency for three-magnon splitting varies with YIG thickness.

Abstract

We report the frequency dependence of the spin current emission in a hybrid ferrimagnetic insulator/normal metal system as function of the insulating layer thickness. The system is based on a yttrium iron garnet (YIG) film [0.2, 1, and 3 \mu m] grown by liquid-phase-epitaxy coupled with a spin current detector of platinum [6 nm]. A strong YIG thickness dependence of the efficiency of the spin pumping has been observed. The highest conversion factor \Delta V/P_{abs} has been demonstrated for the thinner YIG (1.79 and 0.55 mV/mW^{-1} at 2.5 and 10 GHz, respectively) which presents an interest for the realisation of YIG-based devices. A strong YIG thickness dependence of the efficiency of the spin pumping has been also observed and we demonstrate the threshold frequency dependence of the three-magnon splitting process.