# Negative Schottky Barriers and Spin-Polarized Fermi Crossings at WSe2/NbSe2 Interfaces

## TL;DR

This paper explores how the interface between WSe2 and NbSe2 creates spin-polarized Fermi crossings, offering insights for spintronic devices and next-gen transistors.

## Contribution

The study reveals a negative Schottky barrier and tunable spin-polarized Fermi crossings at the WSe2/NbSe2 interface.

## Key findings

- A negative Schottky barrier height of ~−30 meV is observed at the WSe2/NbSe2 interface.
- Spin-polarized charge carriers form a surface-localized Fermi surface at the K-point valleys.
- Increasing WSe2 thickness shifts Fermi pockets from K to Γ, enabling tunable semimetallic phases.

## Abstract

Discovering and engineering spin-polarized surface states
in the
electronic structures of condensed matter systems is a crucial first
step in the development of spintronic devices, wherein spin-polarized
bands crossing the Fermi level can facilitate information transfer.
Here, through nanofocused angle-resolved photoemission spectroscopy
(nano-ARPES) and density functional theory-based calculations, we
show that the interface between monolayer WSe2 and metallic
NbSe2 exhibits a negative Schottky barrier height of ∼
−30 meV: the K-point valleys of the semiconducting layer are
shifted by ∼800 meV to produce a surface-localized Fermi surface
populated only by spin-polarized charge carriers. By increasing the
WSe2 thickness, the Fermi pockets can be moved from K to
Γ, demonstrating tunability of novel semimetallic phases that
exist atop a substrate additionally possessing charge density wave
and superconducting phases. Together, this study provides a spectroscopic
understanding into p-type, Schottky barrier-free interfaces, which
are of urgent interest for bypassing the limitations of current-generation
vertical field effect transistors, in addition to longer-term spintronics
development.