# Angle resolved photoemission spectroscopy reveals spin charge separation in metallic MoSe2 grain boundary

## TL;DR

This study uses angle resolved photoemission spectroscopy to demonstrate that twin-grain boundaries in MoSe2 exhibit one-dimensional metallic behavior with spin-charge separation, indicating potential for quantum device applications.

## Contribution

It provides the first direct evidence of spin-charge separation in grain boundary states of MoSe2 using spectroscopic techniques.

## Key findings

- Observation of parabolic metallic bands at grain boundaries
- Evidence of spinon and holon excitations
- Dispersions match Hubbard model calculations

## Abstract

Material line defects are one-dimensional structures but the search and proof of electron behaviour consistent with the reduced dimension of such defects has been so far unsuccessful. Here we show using angle resolved photoemission spectroscopy that twin-grain boundaries in the layered semiconductor MoSe2 exhibit parabolic metallic bands. The one-dimensional nature is evident from a charge density wave transition, whose periodicity is given by kF/{\pi}, consistent with scanning tunneling microscopy and angle resolved photoemission measurements. Most importantly, we provide evidence for spin- and charge-separation, the hallmark of one-dimensional quantum liquids. Our studies show that the spectral line splits into distinctive spinon and holon excitations whose dispersions exactly follow the energy-momentum dependence calculated by a Hubbard model with suitable finite-range interactions. Our results also imply that quantum wires and junctions can be isolated in line defects of other transition metal dichalcogenides, which may enable quantum transport measurements and devices.