Two-dimensional electron gas tilt-induced Landau level crossings

TL;DR

This paper investigates how tilting the magnetic field in a two-dimensional electron gas affects Landau level crossings and density of states, revealing behavior driven by the tilt angle rather than spin-orbit strength.

Contribution

It introduces a theoretical analysis of Landau level crossings in a 2DEG under tilted magnetic fields, highlighting the role of tilt angle in spin-splitting tuning.

Findings

Landau levels cross at high tilt angles (~87°)

Beats appear in the density of states at crossings

Behavior is due to tilt angle, not just in-plane magnetic field effects

Abstract

This work elucidates the novel behavior found in a two-dimensional electron gas (2DEG) under a tilted magnetic field in which the field's angle becomes the dominant factor in tuning the spin-splitting rather than the strength of the spin-orbit interaction. The 2DEG eigenvalues are derived with Rashba and Zeeman interactions for various tilt angles and they show crossing-free levels except at very high tilt. Moreover, concomitant with the crossings is the appearance of beats in the 2DEG density of states. The crossings from different levels occur consecutively at around 87^{\circ}. Similar new observations in Shubnikov-de Haas experimental measurements by Hatke et al. [1] attributed such phenomena to an in-plane-magnetic-field-induced increase in the effective mass. We show here that this behavior is inherent to a 2DEG where spin-orbit interaction and the in-plane magnetic field contribution are taken into account.