Tunnel magnetoresistance in GaMnAs: Going beyond Jullière formula

Brey, L.; Tejedor, C.; Fernóndez-Rossier, J.
September 2004
Applied Physics Letters;9/13/2004, Vol. 85 Issue 11, p1996
Academic Journal
The relation between tunnel magnetoresistance (TMR) and spin polarization is explored for GaMnAs/GaAlAs/GaMnAs structures where the carriers experience strong spin–orbit interactions. TMR is calculated using the Landauer approach. The materials are described in the 6 band k·p model which includes spin–orbit interaction. Ferromagnetism is described in the virtual crystal mean field approximations. Our results indicate that TMR is a function of spin polarization and barrier thickness. As a result of the stong spin–orbit interactions, TMR also depends on the the angle between current flow direction and the electrode magnetization. These results compromise the validity of Julliere formula.


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