Helical Luttinger liquid on the edge of a 2-dimensional topological antiferromagnet

TL;DR

This paper demonstrates the existence of a helical Luttinger liquid at the edge of a topological antiferromagnet, MnBi2Te4, using direct imaging and conductance measurements, revealing a robust, tunable topological state with potential spintronics applications.

Contribution

It provides experimental evidence of helical Luttinger liquid behavior on the edge of a topological antiferromagnet, a novel topological phase in layered AFM semiconductors.

Findings

Direct imaging of helical edge current in MnBi2Te4.

Edge conductance follows a power-law dependence on temperature and bias.

HLL behavior remains robust under finite magnetic fields below the quantum critical point.

Abstract

Boundary helical Luttinger liquid (HLL) with broken bulk time-reversal symmetry belongs to a unique topological class which may occur in antiferromagnets (AFM). Here, we search for signatures of HLL on the edge of a recently discovered topological AFM, MnBi2Te4 even-layer. Using scanning superconducting quantum interference device, we directly image helical edge current in the AFM ground state appearing at its charge neutral point. Such helical edge state accompanies an insulating bulk which is topologically distinct from the ferromagnetic Chern insulator phase as revealed in a magnetic field driven quantum phase transition. The edge conductance of the AFM order follows a power-law as a function of temperature and source-drain bias which serves as strong evidence for HLL. Such HLL scaling is robust at finite fields below the quantum critical point. The observed HLL in a layered AFM semiconductor represents a highly tunable topological matter compatible with future spintronics and quantum computation.