Electric-field-induced lifting of the valley degeneracy in alpha-(BEDT-TTF)_2I_3 Dirac-like Landau levels

TL;DR

This paper demonstrates that applying an in-plane electric field to alpha-(BEDT-TTF)_2I_3 can lift the valley degeneracy of Dirac-like Landau levels by interacting with the tilt of the Dirac cones, affecting low-energy electronic properties.

Contribution

It introduces a method to control valley degeneracy in organic Dirac materials using electric fields, revealing a new way to manipulate electronic states.

Findings

Electric field lifts valley degeneracy in alpha-(BEDT-TTF)_2I_3

Level spacing varies with electric field and cone tilt

Potential for infrared spectroscopy detection

Abstract

The relativistic Landau levels in the layered organic material alpha-(BEDT-TTF)_2I_3 [BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene] are sensitive to the tilt of the Dirac cones, which, as in the case of graphene, determine the low-energy electronic properties under appropriate pressure. We show that an applied inplane electric field, which happens to be in competition with the tilt of the cones, lifts the twofold valley degeneracy due to a different level spacing. The scenario may be tested in infrared transmission spectroscopy.