Fractional Edge Reconstruction in Integer Quantum Hall Phases

TL;DR

This paper reveals that integer quantum Hall edges can support fractional excitations, challenging the traditional view of a single chiral mode and suggesting new experimental phenomena in topological matter.

Contribution

It demonstrates the formation of fractional edge modes in integer quantum Hall phases, overturning the previous belief of only integer-charge modes.

Findings

Edge modes can support fractional excitations.

Previous observations are explained by fractional modes.

New experimental predictions are proposed.

Abstract

Protected edge modes are the cornerstone of topological states of matter. The simplest example is provided by the integer quantum Hall state at Landau level filling unity, which should feature a single chiral mode carrying electronic excitations. In the presence of a smooth confining potential it was hitherto believed that this picture may only be partially modified by the appearance of additional counterpropagating integer-charge modes. Here, we demonstrate the breakdown of this paradigm: The system favors the formation of edge modes supporting fractional excitations. This accounts for previous observations, and leads to additional predictions amenable to experimental tests.