Magnetotransport properties of Fe/GaAlAs/GaMnAs hybrid magnetic trilayer structures

We discuss tunneling magnetoresistance (TMR) phenomena observed in hybrid magnetic tunnel junctions (MTJs) fabricated from a Fe/GaAlAs/GaMnAs trilayer. The TMR clearly shows abrupt changes of resistance that depends on the relative alignments of magnetization in the two magnetic layers comprising the MTJ. The TMR ratio of the structure strongly depends on the bias voltage, reaching values up to ∼45% when the bias voltage is low (∼0.2 mV). In addition, the device exhibits intermediate TMR values, which correspond to non-collinear alignments of magnetization in the GaMnAs and the Fe layers. Such alignments are possible due to the presence of two magnetic easy axes both in both magnetic layers originating from their strong cubic magnetic anisotropy. The TMR states realized in such Fe/GaAlAs/GaMnAs MTJs are excellent candidates for use in multi-valued memory storage devices.