Phase diagram of bismuth in the extreme quantum limit

TL;DR

This study investigates the behavior of bismuth's electrons in extreme magnetic fields, revealing complex Landau level interactions and electron correlation effects through angular-dependent Nernst measurements.

Contribution

It provides the first detailed experimental mapping of ultraquantum Landau levels and electron interactions in bismuth, confirming theoretical predictions.

Findings

Sharp Nernst peaks at Landau level crossings

Angular dependence matches theoretical models

Additional peaks indicate electron interaction effects

Abstract

Elemental bismuth provides a rare opportunity to explore the fate of a three-dimensional gas of highly mobile electrons confined to their lowest Landau level. Coulomb interaction, neglected in the band picture, is expected to become significant in this extreme quantum limit with poorly understood consequences. Here, we present a study of the angular-dependent Nernst effect in bismuth, which establishes the existence of ultraquantum field scales on top of its complex single-particle spectrum. Each time a Landau level crosses the Fermi level, the Nernst response sharply peaks. All such peaks are resolved by the experiment and their complex angular-dependence is in very good agreement with the theory. Beyond the quantum limit, we resolve additional Nernst peaks signaling a cascade of additional Landau sub-levels caused by electron interaction.