Beating of the oscillations in the transport coefficients of a one-dimensionally periodically modulated two-dimensional electron gas in the presence of spin-orbit interaction

TL;DR

This paper investigates how spin-orbit interaction affects the transport properties and oscillation patterns in a modulated two-dimensional electron gas under a magnetic field, revealing complex beating and splitting phenomena.

Contribution

It introduces a detailed analysis of the interplay between spin-orbit interaction and periodic modulation, showing new flat-band conditions and their impact on oscillations in transport coefficients.

Findings

Weiss and SdH oscillations exhibit beating patterns at small SOI strength.

Strong SOI causes splitting of SdH oscillations into two components.

Flat-band conditions vary with SOI strength, influencing transport behavior.

Abstract

Transport properties of a two-dimensional electron gas (2DEG) are studied in the presence of a perpendicular magnetic field $B$, of a {\it weak} one-dimensional (1D) periodic potential modulation, and of the spin-orbit interaction (SOI) described only by the Rashba term. In the absence of the modulation the SOI mixes the spin-up and spin-down states of neighboring Landau levels into two new, unequally spaced energy branches. The levels of these branches broaden into bands in the presence of the modulation and their bandwidths oscillate with the field $B$. Evaluated at the Fermi energy, the $n$-th level bandwidth of each series has a minimum or vanishes at different values of the field $B$. In contrast with the 1D-modulated 2DEG without SOI, for which only one flat-band condition applies, here there are two flat-band conditions that can change considerably as a function of the SOI strength $\alpha$ and accordingly influence the transport coefficients of the 2DEG. The phase and amplitude of the Weiss and Shubnikov-de Haas (SdH) oscillations depend on the strength $\alpha$. For small values of $\alpha$ both oscillations show beating patterns. Those of the former are due to the independently oscillating bandwidths whereas those of the latter are due to modifications of the density of states, exhibit an even-odd filling factor transition, and are nearly independent of the modulation strength. For strong values of $\alpha$ the SdH oscillations are split in two.