Oscillations of tunneling magnetoresistance on bias voltage in magnetic tunnel junctions with periodic grating barrier

Abstract

A spintronic theory is developed to describe the effect of bias voltages on the magnetic tunnel junctions (MTJs) with a single-crystal barrier. The theory is founded on a conventional optical diffraction method and has already explained the barrier thickness effect, the temperature effect, and the half-metallic electrode effect in the MTJs with a periodic grating barrier. We find that the tunneling magnetoresistance (TMR) will oscillate with the bias voltage. This theoretical result can interpret the bias dependence observed in experiments. The range of bias voltage where the oscillations arise can be regulated by the barrier thickness and the spin polarization of the electrodes. In particular, it demonstrates that the bias voltage smaller than 100mV can hardly change the properties of TMR oscillations on the barrier thickness, which is in agreement with the experiments. Finally, a practical method is proposed to enhance and optimize the output voltage.