Theory of nonspecular tunneling through magnetic tunnel junctions

We derive a simple formalism of vertex corrections for the tunneling probability of an electron due to nonspecular scattering. Predictions of the model in terms of the barrier thickness dependence of the resistance and oscillatory tunneling magnetoresistance (TMR) are in excellent agreement with experiment. We show that the TMR is directly linked to the vertex corrections. Thus, reducing the nonspecular scattering within the barrier layer is crucial for increasing the TMR. Applying this model to the analysis of the temperature dependence of TMR yields a temperature dependent interface scattering rate.