Phase transition and anomalous scaling in the quantum Hall transport of topological insulator Sn-Bi1.1Sb0.9Te2S devices

TL;DR

This paper investigates the quantum Hall transport in topological insulator devices, revealing two distinct scaling regimes, a non-universal critical exponent, and evidence of electron-electron interactions affecting the topological surface states.

Contribution

It provides new insights into the scaling physics and transport mechanisms in topological insulators, highlighting the role of quantum tunneling and electron interactions in quantum Hall effects.

Findings

Two exponential scaling regimes in temperature-dependent dissipation

Scaling relations with a critical exponent of ~0.2, half the universal value

Evidence of percolation assisted by quantum tunneling and electron-electron interactions

Abstract

The scaling physics of quantum Hall transport in optimized topological insulators with a plateau precision of ~1/1000 e2/h is considered. Two exponential scaling regimes are observed in temperature-dependent transport dissipation, one of which accords with thermal activation behavior with a gap of 2.8 meV (> 20 K), the other being attributed to variable range hopping (1-20 K). Magnetic field-driven plateau-to-plateau transition gives scaling relations of (dR$_{xy}$/dB)$^{max}$ \propto T$^{-\kappa}$ and \DeltaB$^{-1}$ \propto T$^{-\kappa}$ with a consistent exponent of \kappa ~ 0.2, which is half the universal value for a conventional two-dimensional electron gas. This is evidence of percolation assisted by quantum tunneling, and reveals the dominance of electron-electron interaction of the topological surface states.