Magnetothermoelectric properties of Bi2Se3

TL;DR

This study investigates the thermoelectric and quantum oscillation properties of Bi2Se3 at low temperatures and high magnetic fields, revealing insights into its Fermi surface, Landau levels, and the influence of bulk carriers on surface states.

Contribution

It provides a detailed analysis of entropy transport, quantum oscillations, and Landau level spectrum in Bi2Se3, highlighting the impact of bulk carriers on surface state properties.

Findings

Seebeck coefficient tracks Fermi temperature across carrier concentrations

Giant quantum oscillations in Nernst response observed

Large g-factor and decreasing Fermi energy with magnetic field

Abstract

We present a study of entropy transport in Bi2Se3 at low temperatures and high magnetic fields. In the zero-temperature limit, the magnitude of the Seebeck coefficient quantitatively tracks the Fermi temperature of the 3D Fermi surface at \Gamma-point as the carrier concentration changes by two orders of magnitude (10$^{17}$ to 10$^{19}$cm$^{-3}$). In high magnetic fields, the Nernst response displays giant quantum oscillations indicating that this feature is not exclusive to compensated semi-metals. A comprehensive analysis of the Landau Level spectrum firmly establishes a large $g$-factor in this material and a substantial decrease of the Fermi energy with increasing magnetic field across the quantum limit. Thus, the presence of bulk carriers significantly affects the spectrum of the intensively debated surface states in Bi2Se3 and related materials.