Analysis of anisotropic tunnel magneto-resistance of (Ga,Mn)As/AlAs/(Ga,Mn)As magnetic tunnel junction

Abstract

Anisotropic tunnel magneto-resistance (TMR) of (Ga,Mn)As/AlAs/(Ga,Mn)As magnetic tunnel junctions (MTJs) was investigated by both experimentation and simulation. The TMR ratios measured at 8 K for the fabricated MTJs with magnetic fields applied in the ( 0 0 1 ) plane along the [ 1 0 0 ] , [ 1 1 0 ] , and [ 1 1 ¯ 0 ] directions were 39%, 19%, and 10%. These asymmetrical TMR ratios can be explained by the magnetic anisotropy of (Ga,Mn)As, in which the cubic magnetic anisotropy dominated the magnetization switching with its easy axis along the 〈 1 0 0 〉 directions, whereas the uniaxial anisotropy contributed slightly with its easy axis along the [ 1 1 0 ] direction. Two models of magnetization reversal were considered: (1) the coherent rotation model and (2) the domain-wall displacement model, for the analysis. As a result, the domain-wall displacement model accurately explained both the TMR ratio and switching field of the fabricated MTJ with 8 × 8 μ m 2 junction size.