Role of quantum confinement and interlayer coupling in CrI3 -graphene magnetic tunnel junctions

Abstract

Recent demonstrations of magnetic ordering and spin transport in two-dimensional heterostructures have opened research venues in these material systems. In order to control and enhance the tunneling magnetoresistance phenomena in 2D magnetic heterostructures beyond phenomenological descriptions, quantitative estimates of tunneling rates in terms of the atomic details are required. Here we combine first principles and quantum ballistic transport calculations to shed important insights from an atomistic viewpoint on the underlying mechanisms governing spin transport in graphene/CrI 3 junctions. Descriptions of the electronic structure reveal that tunneling is the dominant transport mechanism in these heterostructures and helps differentiate intermediate metamagnetic states present in the switching process. We find that quantum confinement and layer-layer interactions are key to describing transport in these two-dimensional systems. Ballistic transport calculations further support these findings and yield magnetoresistance values in remarkable agreement with experiments. The short width of these barriers limits analysis solely based on the bulk complex band structure often employed in the description of magnetic tunnel junctions. Our work devises mechanisms to attain larger tunneling magnetoresistances, proving valuable to the advancement of spin valves in layered heterostructures.

Recent progress and challenges in magnetic tunnel junctions with 2D materials for spintronic applications

“…For example, Heath et al 172 In order to manipulate spin in non-magnetic 2D materials, one can dope them by charge transfer from FM metals or proximity-induced spin splitting in themselves. For example, Asshoff et al 167…”

Theoretical study on the quantum well junction CrI3/CrGeTe3

“…That idea of conducting in one direction (x-direction) allows to constructing a two-dimensional (2D) layered materials which show fascinating possibilities [10,11,12]. The CrI3 have been extensively studied, where it is provide a new window into magnetic insulators which are a resource for next-generation topological devices [13,14,15,16,12,17,18,19,20,21]. Twodimensional monolayer crys-tal of CrI3 in its equilibrium con guration is a ferromagnetic semiconductor.…”

Large Magnetoresistance and Efficient Spin Injection in Ferromagnet/Graphene/Fe3GeTe2 Van der Waals Magnetic Tunnel Junctions

“…Very recently, the discovery of magnetic order in 2D materials, Fe 3 GeTe 2 (FGT), , Cr 2 Ge 2 Te 6 , VSe 2 , and CrI 3 , has re-stimulated the MTJs research due to their novel physical phenomena. − In particular, FGT is recognized as a promising electrode material due to its metallic nature, large perpendicular magnetocrystalline anisotropy, , and relatively high Curie temperature . Extensive studies have been devoted to the spin-dependent transport of vdW MTJs with FGT as ferromagnetic layers and various vdw 2D materials (e.g., graphene, graphite, h-BN, MoS 2 ) as spacer layers from both theory − and experiments. − Despite these interesting studies, MTJs based on conventional FM materials as electrodes and newly discovered 2D magnetic materials as spacer layers remain unexplored at present.…”