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

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.

After we received the referee's comment, we conducted additional experiments based on reviewer's advice. As the result, we have found the problem of the reproducibility in our experiments. In fact, we observed larger SMR at new experiments, however, the mechanism has not been clear. Therefore, we decided to withdraw the paper once, and reconsider the results