Nonchiral Edge States at the Chiral Metal Insulator Transition in Disordered Quantum Hall Wires

TL;DR

This paper investigates the quantum phase diagram of disordered quantum Hall wires, revealing the existence of nonchiral edge states at the chiral metal-insulator transition, which are distinct from other known states.

Contribution

It identifies and characterizes nonchiral edge states at the CMIT, showing their dependence on wire width and their unique properties compared to other quantum Hall states.

Findings

Discontinuous conductance transitions at the CMIT.

Nonchiral edge states are superpositions of opposite chirality edge states.

Bulk contribution of these states decreases with increasing wire width.

Abstract

The quantum phase diagram of disordered wires in a strong magnetic field is studied as a function of wire width and energy. The two-terminal conductance shows zero-temperature discontinuous transitions between exactly integer plateau values and zero. In the vicinity of this transition, the chiral metal-insulator transition (CMIT), states are identified that are superpositions of edge states with opposite chirality. The bulk contribution of such states is found to decrease with increasing wire width. Based on exact diagonalization results for the eigenstates and their participation ratios, we conclude that these states are characteristic for the CMIT, have the appearance of nonchiral edges states, and are thereby distinguishable from other states in the quantum Hall wire, namely, extended edge states, two-dimensionally (2D) localized, quasi-1D localized, and 2D critical states.