Spin-dependent transport in van der Waals magnetic tunnel junctions with Fe3GeTe2 electrodes

TL;DR

This study uses density functional theory to predict giant tunneling magnetoresistance in van der Waals magnetic tunnel junctions with Fe3GeTe2 electrodes, promising for spintronic applications.

Contribution

It demonstrates that vdW MTJs with Fe3GeTe2 electrodes exhibit robust giant TMR effects independent of spacer layer type and interface variations, advancing spintronic device design.

Findings

Junction resistance changes by thousands of percent with magnetic alignment.

Giant TMR effect driven by electronic structure mismatch in spin channels.

Robust TMR effect unaffected by spacer layer type, strain, or lattice mismatch.

Abstract

Van der Waals (vdW) heterostructures, stacking different two-dimensional materials, have opened up unprecedented opportunities to explore new physics and device concepts. Especially interesting are recently discovered two-dimensional magnetic vdW materials, providing new paradigms for spintronic applications. Here, using density functional theory (DFT) calculations, we investigate the spin-dependent electronic transport across vdW magnetic tunnel junctions (MTJs) composed of Fe3GeTe2 ferromagnetic electrodes and a graphene or hexagonal boron nitride (h-BN) spacer layer. For both types of junctions, we find that the junction resistance changes by thousands of percent when the magnetization of the electrodes is switched from parallel to antiparallel. Such a giant tunneling magnetoresistance (TMR) effect is driven by dissimilar electronic structure of the two spin-conducting channels in Fe3GeTe2, resulting in a mismatch between the incoming and outgoing Bloch states in the electrodes and thus suppressed transmission for an antiparallel-aligned MTJ. The vdW bounding between electrodes and a spacer layer makes this result virtually independent of the type of the spacer layer, making the predicted giant TMR effect robust with respect to strain, lattice mismatch, interface distance and other parameters which may vary in the experiment. We hope that our results will further stimulate experimental studies of vdW MTJs and pave the way for their applications in spintronics.