Probing the Role of the Barrier Layer in Magnetic Tunnel Junction Transport

TL;DR

This study investigates how the magnetic state of the barrier layer in magnetic tunnel junctions influences electron transport, revealing different dominant scattering mechanisms in paramagnetic versus ferrimagnetic states.

Contribution

It provides new insights into the role of the barrier layer's magnetic properties in tunneling, highlighting the impact of spin wave scattering within the barrier.

Findings

Spin polarized transport is dominated by interface scattering when the barrier is paramagnetic.

Spin flip scattering within the barrier dominates when the barrier is ferrimagnetic.

The magnetic state of the barrier significantly affects tunneling mechanisms.

Abstract

Magnetic tunnel junctions with a ferrimagnetic barrier layer have been studied to understand the role of the barrier layer in the tunneling process - a factor that has been largely overlooked until recently. Epitaxial oxide junctions of highly spin polarized La0.7Sr0.3MnO3 and Fe3O4 electrodes with magnetic NiMn2O4 (NMO) insulating barrier layers provide a magnetic tunnel junction system in which we can probe the effect of the barrier by comparing junction behavior above and below the Curie temperature of the barrier layer. When the barrier is paramagnetic, the spin polarized transport is dominated by interface scattering and surface spin waves; however, when the barrier is ferrimagnetic, spin flip scattering due to spin waves within the NMO barrier dominates the transport.