Impact of electron-electron interactions induced by disorder at interfaces on spin-dependent tunneling in Co-Fe-B/MgO/Co-Fe-B magnetic tunnel junctions

Abstract

In this study, we demonstrate that, beyond the standard magnon excitations, the electron-electron interactions in presence of disorder in CoFeB electrodes play a significant role on the zero-bias anomaly measured in CoFeB/MgO/CoFeB junctions. The low-temperature dependence of the tunneling conductance presents cusplike dip at low voltage varying as the square root of the bias voltage. The amplitude of this zero-bias anomaly decreases with the annealing temperature, indicating interface crystallization and related increase in the tunnel magnetoresistance.