Abstract
We predict that the spin-transfer, , and fieldlike, , components of the local spin torque are dramatically enhanced in double-barrier magnetic tunnel junctions. The spin-mixing enhancement is due to the energetic proximity of majority and minority quantum well states (QWSs) of different quantum numbers within the bias window. The local-spin-torque enhancement is not associated with a corresponding enhancement of the spin-polarized currents. exhibits a switch-on and switch-off steplike bias behavior when spin-polarized QWSs enter the bias window or exit the energy band, while changes sign between switch-on biases. The net exhibits an anomalous angular behavior due to the bias interplay of the bilinear and biquadratic effective exchange couplings.
2 More- Received 4 October 2007
DOI:https://doi.org/10.1103/PhysRevB.76.224406
©2007 American Physical Society