Zero-field dissipationless chiral edge transport and the nature of dissipation in the quantum anomalous Hall state

TL;DR

This paper provides experimental evidence for dissipationless chiral edge transport in the quantum anomalous Hall effect at zero magnetic field, clarifying the nature of dissipation and the temperature limits of the effect.

Contribution

It unambiguously demonstrates dissipationless edge transport in the QAH state and identifies the origins of dissipative channels, advancing understanding of the effect's temperature constraints.

Findings

Confirmed dissipationless chiral edge transport at zero magnetic field.

Identified the origin of dissipative channels in the QAH state.

Found the critical temperature of the QAH effect is much lower than the Curie temperature.

Abstract

The quantum anomalous Hall (QAH) effect is predicted to possess, at zero magnetic field, chiral edge channels that conduct spin polarized current without dissipation. While edge channels have been observed in previous experimental studies of the QAH effect, their dissipationless nature at a zero magnetic field has not been convincingly demonstrated. By a comprehensive experimental study of the gate and temperature dependences of local and nonlocal magnetoresistance, we unambiguously establish the dissipationless edge transport. By studying the onset of dissipation, we also identify the origin of dissipative channels and clarify the surprising observation that the critical temperature of the QAH effect is two orders of magnitude smaller than the Curie temperature of ferromagnetism.