Room temperature magnetic barrier layers in magnetic tunnel junctions

Abstract

We investigate the spin transport and interfacial magnetism of magnetic tunnel junctions with highly spin polarized La0.7Sr 0.3MnO3 (LSMO) and Fe3O4 electrodes and a ferrimagnetic NiFe2O4 (NFO) barrier layer. The spin-dependent transport can be understood in terms of magnon-assisted spin-dependent tunneling where the magnons are excited in the barrier layer itself. The NFO/ Fe3O4 interface displays strong magnetic coupling, while the LSMO/NFO interface exhibits clear decoupling as determined by a combination of x-ray absorption spectroscopy and x-ray magnetic circular dichroism. This decoupling allows for distinct parallel and antiparallel electrode states in this all-magnetic trilayer. The spin transport of these devices, dominated by the NFO barrier layer magnetism, leads to a symmetric bias dependence of the junction magnetoresistance at all temperatures. © 2010 The American Physical Society.