Spin-dependent Schottky barriers and vacancy-induced spin-selective ohmic contacts in magnetic vdW heterostructures

Abstract

The 2D ferromagnets, such as CrX3 (X=Cl, Br and I), have been attracting extensive attentions since they provide novel platforms to fundamental physics and device applications. Integrating CrX3 with other electrodes and substrates is an essential step to their device realization. Therefore, it is important to understand the interfacial properties between CrX3 and other 2D materials. As an illustrative example, we have investigated the heterostructures between CrX3 and graphene (CrX3/Gr) from firstprinciples. We find unique Schottky contacts type with strongly spin-dependent barriers in CrX3/Gr. This can be understood by synergistic effects between the exchange splitting of semiconductor band of CrX3 and interlayer charge transfer. The spinasymmetry of Schottky barriers may result in different tunneling rates of spin-up and down electrons, and then lead to spin-polarized current, namely spin-filter (SF) effect. Moreover, by introducing X vacancy into CrX3/Gr, an Ohmic contact forms in spin-up direction. It may enhance the transport of spin-up electrons, and improve SF effect. Our systematic study reveals the unique interfacial properties of CrX3/Gr, and provides a theoretical view to the understanding and designing of spintronics device based on magnetic vdW heterostructures.

Spin‐Transport through Van der Waals Heterojunctions Based on 2D‐Ferromagnet and Transition Metal Dichalcogenides: A Study from First‐Principles Calculations

“…[25] The report shows that thicker samples with smaller work functions in graphene electrodes generally show higher TMR. Spin-dependent Schottky barrier at the CrX 3 /graphene interface has been reported in the last year by Li et al [22] These recent studies suggest that CrX 3 based compounds/heterostructures could suit spintronic applications. Therefore, it would be interesting to study the spin transport through heterojunctions consisting of CrX 3 and other interesting 2D materials, namely, the transition metal dichalcogenides (TMDC).…”

“…These values are comparable to the previously reported CrX 3 /graphene tunneling barrier heights. [22] Although the tunneling barriers present in CrX 3 /TMDC heterostructures are independent of the electron's spin, the Schottky barrier heights are highly spin-sensitive. Therefore, these heterostructures can induce a highly spin-polarized transmission through the interface.…”

“…The flat atomic interface in Van der Waals heterostructures can render uniform tunneling throughout the interface. [ 22 ] In addition, the interlayer space in Van der Waals heterostructures can serve as a natural tunneling barrier. Both experimental and theoretical studies have recently been carried out to study the magnetoresistance in heterojunctions consisting of 2D ferromagnets.…”

“…Spin‐dependent Schottky barrier at the CrX 3 /graphene interface has been reported in the last year by Li et al. [ 22 ]…”

Hybridized bands and stacking-dependent band edges in ferromagnetic Fe3GeTe2/CrGeTe3 moiré heterobilayer

“…Recently, heterostructures consisting of 2D ferromagnetic (FM) vdW layered materials have attracted considerable interest 8 – 10 . In particular, research on the 2D vdW heterobilayer composed of magnetic metals and magnetic semiconductors is still early, as it was only recently revealed that vdW monolayer (ML) or few-layer materials retain magnetism 11 – 13 . Furthermore, the recent discovery of novel properties of twisted vdW nonmagnetic homo and heterobilayers 14 – 16 further prompts the investigation of twisted vdW magnetic homo and heterobilayers.…”