Modeling of bias anomaly in (Ga,Mn)As tunneling magnetoresistance structures

Abstract

We develop a simplified, Slonczewski-type model for the spin-dependent tunneling in (Ga,Mn)As-based trilayers to study the features that influence the bias anomaly, i.e., the drop in tunneling magnetoresistance (TMR) with the bias in these structures. By using the obtained closed formulas, we show that the value of TMR can be increased and the bias anomaly can be reduced by appropriate engineering of the barrier height and of the properties (magnetic ion content, hole concentration) of the dilute ferromagnetic semiconductor leads. Finally, we use the model to describe spin-dependent tunneling in one-dimensional TMR structures and show that in the limit of infinite barrier, our approach corresponds to the Jullière model.