Enhancement of spin Hall magnetoresistance effect in CoFe2O4/Pt/CoFe2O4 trilayers

TL;DR

This study demonstrates that CoFe2O4/Pt/CoFe2O4 trilayers significantly enhance spin Hall magnetoresistance compared to bilayers, with SMR ratios influenced by Pt thickness and interference effects, advancing understanding of spin current phenomena.

Contribution

The paper introduces a trilayer structure that amplifies SMR effects and analyzes the influence of layer thickness and interference, providing new insights into spin current manipulation.

Findings

SMR ratio in trilayers is four times higher than in bilayers.

SMR ratio depends on Pt layer thickness due to interference effects.

Parameters like spin diffusion length and mixing conductance were derived.

Abstract

The spin Hall magnetoresistance (SMR) phenomenon includes the fundamental physics of spin current, and originates from spin accumulation at an interface owing to the spin Hall effect. Although bilayers are the simplest structure exhibiting SMR, these exploit spin accumulation at only one side of a layer. Herein, trilayers of CoFe2O4/Pt/CoFe2O4 were fabricated and their spin Hall magnetoresistance was investigated. The trilayer structure featuring a thin Pt layer exhibited an SMR ratio four times that of a CoFe2O4/Pt bilayer. Further, the SMR ratio exhibited a dependence on Pt layer thickness that can be attributed to interference of the spin accumulations at both sides. Herein, several parameters such as spin diffusion length and mixing conductance were derived using the theory of Chen et al.