Conductance resonances and crossing of the edge channels in the quantum Hall ferromagnet state of Cd(Mn)Te microstructures

TL;DR

This paper investigates high magnetoconductance peaks in Cd(Mn)Te microstructures, revealing edge channel crossings and topological defects in the quantum Hall ferromagnet state, with controllable channel crossings via voltage application.

Contribution

It demonstrates the spontaneous lifting of edge channel degeneracy and controllable crossing of chiral channels in quantum Hall ferromagnets, supported by experimental and theoretical analysis.

Findings

High and narrow magnetoconductance peaks observed.

Edge channels can cross, forming topological defects.

Channel crossings can be induced by voltage control.

Abstract

In this paper we report on the observation of very high and narrow magnetoconductance peaks which we attribute to the transition to quantum Hall ferromagnet (QHFM) state occurring at the edges of the sample. We show that the expected spatial degeneracy of chiral edge channels is spontaneously lifted in agreement with theoretical studies performed within the Hartree-Fock approximation. We indicate also that separated edge currents which flow in parallel, may nevertheless cross at certain points, giving rise to the formation of topological defects or one-dimensional magnetic domains. Furthermore, we find that such local crossing of chiral channels can be induced on demand by coupling spin states of a Landau level to different current terminals and applying a DC source-drain voltage.