Resonant tunneling effect and tunneling magnetoresistance in GaMnAs quantum-well double-barrier heterostructures

摘要

We have investigated the d~2 I/dV~2-V characteristics and tunneling magnetoresistance (TMR) in the GaMnAs quantum-well (QW) double-barier heterostructures, and compared them with those of the GaMnAs-based single-barrier heterostructure. We obtained a relatively high TMR ratio of 126.5% in the single-barrier heterostructure at 2.6 K. The value of d~2 I /dV~2 and the TMR ratio of this single-barrier heterostructure monotonically approached zero with increasing the bias voltage. On the other hand, in the double-barrier structures, oscillatory behaviors were seen in the negative bias region of d~2 I/dV~2-V curves. With increasing the QW width, these peaks shifted to a smaller voltage and the period of the oscillation became short. This means that these oscillatory behaviors are induced by the resonant tunneling effect mediated by holes tunneling through the GaMnAs QW. Also, we observed that TMR is increased at these resonant peak bias voltages in the double-barrier heterostructures.