Multifractal conductance fluctuations in high-mobility graphene in the Integer Quantum Hall regime

TL;DR

This study provides the first experimental evidence of multifractality in conductance fluctuations at a topological phase transition in high-mobility graphene, revealing new insights into quantum Hall physics.

Contribution

It demonstrates the observation of multifractality in conductance at a topological phase transition in graphene, highlighting the importance of high mobility and critical points for such phenomena.

Findings

Multifractality appears at the integer quantum Hall plateau transition.

High-mobility graphene devices are essential to observe this effect.

Multifractality diminishes as the chemical potential moves away from critical points.

Abstract

We present the first experimental evidence for the multifractality of a transport property at a topological phase transition. In particular, we show that conductance fluctuations display multifractality at the integer-quantum-Hall $\nu=1 \longleftrightarrow \nu=2$ plateau-to-plateau transition in a high-mobility mesoscopic graphene device. We establish that to observe this multifractality, it is crucial to work with very high-mobility devices with a well-defined critical point. This multifractality gets rapidly suppressed as the chemical potential moves away from these critical points. Our combination of multifractal analysis with state-of-the-art transport measurements at a topological phase transition provides a novel method for probing such phase transitions in mesoscopic devices.