Magnetic Anisotropy Study for GaMnAs-Based Magnetic Tunnel Junction

概要

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Magnetic anisotropy of GaMnAs/AlAs/GaMnAs magnetic tunnel junctions (MTJs) was investigated through tunnel magnetoresistance (TMR). The TMR ratio measured at 8 K for the fabricated MTJs took its maximum value of approximately 39% along the $\langle 100\rangle$ direction, and decreased to about 19 and 10% in the [110] and [1$\bar{1}$0] directions, respectively. This anisotropic TMR ratio suggests that the cubic magnetic anisotropy with its easy axis along the $\langle 100\rangle$ directions is dominant, whereas the uniaxial anisotropy with its easy axis along the [110] direction slightly exists. The domain-wall displacement model, rather than the coherent rotation model, accurately explained the angular dependences of both the switching field and the TMR ratios. Temperature dependences of anisotropic TMR ratios revealed that lower than 25 K the maximum TMR ratio was obtained along the $\langle 100\rangle$ directions, whereas higher than 25 K the maximum was obtained along the [110] direction, indicating crossover of the easy axis directions.
Japan Society of Applied Physicsの論文
2005-10-10