Abstract
We investigate the spin transport and interfacial magnetism of magnetic tunnel junctions with highly spin polarized La0.7Sr0.3MnO3 (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.