Observation of linearly dispersive edge modes in a magnetic Weyl semimetal Co3Sn2S2

TL;DR

This study demonstrates the existence of linearly dispersive chiral edge modes in the magnetic Weyl semimetal Co3Sn2S2, providing insights into higher temperature quantum anomalous Hall effect realization through surface states.

Contribution

The paper combines experimental STM measurements with theoretical modeling to reveal chiral edge states on the surface of Co3Sn2S2, a magnetic Weyl semimetal, suggesting a new platform for robust QAHE.

Findings

Linearly dispersing edge states observed on Co3Sn2S2 surfaces.

Chiral edge modes localized on Kagome planes.

Potential for higher temperature QAHE realization.

Abstract

The physical realization of Chern insulators is of fundamental and practical interest, as they are predicted to host the quantum anomalous Hall effect (QAHE) and topologically protected chiral edge states which can carry dissipationless current. The realization of the QAHE state has however been challenging because of the complex heterostructures and sub-Kelvin temperatures required. Time-reversal symmetry breaking Weyl semimetals, being essentially stacks of Chern insulators with inter-layer coupling, may provide a new platform for the higher temperature realization of robust QAHE edge states. In this work we present a combined scanning tunneling spectroscopy and theoretical investigation of a newly discovered magnetic Weyl semimetal, Co3Sn2S2. Using modeling and numerical simulations we find that chiral edge states can be localized on partially exposed Kagome planes on the surface of a Weyl semimetal. Correspondingly, our STM dI/dV maps on narrow kagome Co3Sn terraces show linearly dispersing quantum well like states, which can be attributed to hybridized chiral edge modes. Our experiment and theory results suggest a new paradigm for studying chiral edge modes in time-reversal breaking Weyl semimetals. More importantly, this work leads a practical route for realizing higher temperature QAHE.