Infrared magneto-spectroscopy of graphite in tilted fields

TL;DR

This study uses infrared magneto-spectroscopy to explore how tilted magnetic fields affect the electronic structure of Bernal-stacked graphite, revealing Landau level degeneracy lifting and behavior of Dirac fermions.

Contribution

It provides new insights into the effects of tilted magnetic fields on graphite's electronic structure, particularly the degeneracy lifting at the H point.

Findings

Broadening and splitting of interband Landau level transitions observed.

Degeneracy of Landau levels at the H point is lifted by in-plane magnetic fields.

Charge carriers at the H point behave as massless Dirac fermions.

Abstract

The electronic structure of Bernal-stacked graphite subject to tilted magnetic fields has been investigated using infrared magneto-transmission experiments. With the increasing in-plane component of the magnetic field B, we observe significant broadening and partially also splitting of interband inter-Landau level transitions, which originate at the H point of the graphite Brillouin zone, where the charge carriers behave as massless Dirac fermions. The observed behavior is attributed to the lifting of the twofold degeneracy of Landau levels at the H point - a degeneracy which in graphite complements the standard spin and valley degeneracies typical of graphene.