Quantum-limit Hall effect with large carrier density in topological semimetals

TL;DR

This paper proposes a method to achieve the quantum-limit Hall effect in topological semimetals with high carrier densities, challenging traditional requirements of low density and strong magnetic fields, and revealing new quantum phenomena.

Contribution

It introduces a novel approach to realize quantum-limit Hall effect in topological semimetals with large residual carrier densities, bypassing the need for extremely strong magnetic fields.

Findings

Quantum-limit Hall effect can occur with large carrier densities.

The filling factor  is explicitly shown to violate Onsager's relation.

A single Fermi surface can host both electron and hole carriers.

Abstract

The quantum-limit Hall effect at $\nu = nh/eB\sim O(1)$ that hosts a variety of exotic quantum phenomena requires demanding strong magnetic field $B$ and low carrier density $n$. We propose to realize quantum-limit Hall effect even in the presence of large carrier density residues $n_e$ and $n_h$ relative to the magnetic field $B$ in topological semimetals, where a single Fermi surface contour allow both electron-type and hole-type carriers and approaches charge neutrality as $n_e\sim n_h$. The underlying filling factor $\nu = |n_e-n_h|h/eB$ explicitly violates the Onsager's relation for quantum oscillations.