Effect of oxidizing the ferromagnetic electrode in magnetic tunnel junctions on tunneling magnetoresistance

Abstract

The ferromagnetic layer in magnetic tunnel junctions (MTJs) was oxidized with varying O-2 concentrations, and the corresponding effect on spin-dependent transport was studied. As expected from our previous results for MTJs with an over-oxidized AlOx tunnel barrier, a partially oxidized ferromagnetic layer plays an important role in spin-dependent transport. As the temperature is lowered, the junction resistance increases dramatically, and the tunneling magnetoresistance (TMR) is strongly suppressed. Increasing the O-2 concentration enhances the increase of resistance and suppression of TMR. This work supports our previous conclusion that oxidizing the ferromagnetic layer generates localized magnetic moments, which act as a scattering center for spin-polarized tunneling electrons. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4704557]