Quantum Nernst Effect in a Bismuth Single Crystal

TL;DR

This paper models the phonon-drag contribution to the Nernst effect in bismuth under magnetic fields, successfully explaining experimental oscillations and the dominance of the Nernst signal over the Seebeck effect.

Contribution

It provides a theoretical calculation of the phonon-drag contribution to the Nernst effect in bismuth, matching experimental observations and explaining previously unexplained features.

Findings

Reproduces the magnitude and temperature dependence of Nernst peaks

Explains the large Nernst signal compared to Seebeck effect

Identifies electron Landau levels as origins of minor peaks

Abstract

We calculate the phonon-drag contribution to the transverse (Nernst) thermoelectric power $S_{yx}$ in a bismuth single crystal subjected to a quantizing magnetic field. The calculated heights of the Nernst peaks originating from the hole Landau levels and their temperature dependence reproduce the right order of magnitude for those of the pronounced magneto-oscillations recently reported by Behnia et al [Phys.Rev.Lett. 98, 166602 (2007)]. A striking experimental finding that $S_{yx}$ is much larger than the longitudinal (Seebeck) thermoelectric power $S_{xx}$ can be naturally explained as the effect of the phonon drag, combined with the well-known relation between the longitudinal and the Hall resistivity $rho_{xx}>>|rho_{yx}|$ in a semi-metal bismuth. The calculation that includes the contribution of both holes and electrons suggests that some of the hitherto unexplained minor peaks located roughly at the fractional filling of the hole Landau levels are attributable to the electron Landau levels.