Nernst quantum oscillations in bulk semi-metals

TL;DR

This paper investigates quantum oscillations in the Nernst effect in bulk semi-metals bismuth and graphite under magnetic fields, revealing unexpected peaks beyond the quantum limit linked to sample purity.

Contribution

It reports the observation of unexpected Nernst peaks beyond the quantum limit in bismuth, suggesting new phenomena not explained by non-interacting models.

Findings

Nernst peaks sharply occur at Landau tube squeezing.

Unexpected Nernst peaks are observed beyond the quantum limit.

Peak amplitudes are larger in samples with longer electron mean-free-path.

Abstract

With a widely available magnetic field of 10 T, one can attain the quantum limit in bismuth and graphite. At zero magnetic field, these two elemental semi-metals host a dilute liquid of carriers of both signs. When the quantum limit is attained, all quasi-particles are confined to a few Landau tubes. Each time a Landau tube is squeezed before definitely leaving the Fermi surface, the Nernst response sharply peaks. In bismuth, additional Nernst peaks, unexpected in the non-interacting picture, are resolved beyond the quantum limit. The amplitude of these unexpected Nernst peaks is larger in the samples with the longest electron mean-free-path.