Oxidation kinetics of tunnel barrier and its effect on exchange bias of proximity interface

Abstract

Atomic migration in metallic multilayers of magnetic tunnel junction (MTJ), and consequent compositional modulation at the interface during plasma oxidation of an Al tunnel barrier is reported. Surprising effects of such modulation in our specific MTJ appear as the systematic increase in exchange bias of the NiFe buffer layer beneath an FeMn antiferromagnet. Cation-current-limited oxidation of the Al metal layer drives atomic migration in the underlying multilayers to compensate for the cation vacancies created in the metal side of the metal/oxide interface. The condition of oxide growth which manifests different migration behavior is also discussed. (C) 2001 American Institute of Physics.