# Are thermal fluctuations the sole reason for finite longitudinal resistance in quantum anomalous Hall experiments?

## TL;DR

This paper investigates whether thermal fluctuations are the only cause of finite longitudinal resistance in quantum anomalous Hall systems, showing that disorder and inelastic scattering can produce similar effects even at zero temperature.

## Contribution

The study demonstrates that disorder and inelastic scattering can induce finite longitudinal resistance in QAH systems, challenging the notion that thermal fluctuations are the sole cause.

## Key findings

- Finite longitudinal resistance can arise from disorder and inelastic scattering.
- Similar effects occur at zero temperature, not just due to thermal fluctuations.
- Disorder impacts the robustness of the quantum anomalous Hall effect.

## Abstract

In some recent experiments [A. J. Bestwick, et. al., Phys. Rev. Lett. 114, 187201 (2015), Cui-Zu Chang, et. al., Nat. Materials. 14, 473-477 (2015)] it has been shown that in observations of the quantum anomalous Hall (QAH) effect the longitudinal resistance $R_L$ increases as temperature $T$ increases, while Hall resistance $R_H$ loses its quantization with increase in $T$. This behavior was explained due to increased thermal fluctuations as $T$ increases. We show that similar effects arise in QAH samples with quasi-helical edge modes as disorder increases in presence of inelastic scattering or otherwise even at temperature $T=0$.