Electrode band structure effects in thin MgO magnetic tunnel junctions

Abstract

In this study, we demonstrate that, beyond the standard magnon excitations, the electronic band structure of the electrodes plays a significant role on the low bias voltage window (0 < |V| < 0.4 V) of the tunnel magnetoresistance (TMR) in thin MgO-CoFeB junctions. The tunneling conductance in the parallel state presents a minimum at about ±0.35 and ±0.3 V for the negative and positive bias, respectively. The presence of this minimum indicates a related decrease in the TMR(V). These observations are explained by the electronic band structures of bcc-Fe and Co.