Gap states and valley-spin filtering in transition metal dichalcogenide monolayers

TL;DR

This paper investigates how metal-induced gap states influence valley-spin filtering in transition metal dichalcogenide monolayers, providing a fundamental understanding and design guidelines for efficient valley-spin filter devices.

Contribution

It introduces the concept of MIGS as a key mechanism in valley-spin filtering and analyzes their role in transport processes at the electrode/monolayer interface.

Findings

MIGS mediate valley- and spin-resolved charge transport.

Filtering effectiveness increases as channel length decreases.

Provides scaling trends for valley-spin selectivity.

Abstract

The magnetically-induced valley-spin filtering in transition metal dichalcogenide monolayers ($MX_{2}$, where $M$=Mo, W and $X$=S, Se, Te) promises new paradigm in information processing. However, the detailed understanding of this effect is still limited, regarding its underlying transport processes. Herein, it is suggested that the filtering mechanism can be greately elucidated by the concept of metal-induced gap states (MIGS), appearing in the electrode-terminated $MX_{2}$ materials {\it i.e.} the referential filter setup. In particular, the gap states are predicted here to mediate valley- and spin-resolved charge transport near the ideal electrode/$MX_{2}$ interface, and therefore to initiate filtering. It is also argued that the role of MIGS increases when the channel length is diminished, as they begin to govern the overall valley-spin transport in the tunneling regime. In what follows, the presented study yields fundamental scaling trends for the valley-spin selectivity with respect to the intrinsic physics of the filter materials. As a result, it facilitates insight into the analyzed effects and provide design guidelines toward efficient valley-spin filter devices, that base on the discussed materials or other hexagonal monolayers with a broken inversion symmetry.