Modulation of the Shubnikov-de Haas Oscillation in Unidirectional Lateral Superlattices

TL;DR

This paper investigates how a weak unidirectional periodic potential affects the amplitude and phase of Shubnikov-de Haas oscillations in 2D electron gases, revealing suppression and enhancement effects linked to magnetic field strength.

Contribution

It provides a detailed experimental and theoretical analysis of the modulation effects on oscillations, highlighting the roles of collisional and diffusion contributions across magnetic fields.

Findings

Amplitude suppression and phase inversion at low magnetic fields.

Transition from suppression to enhancement with increasing magnetic fields.

Semi-quantitative agreement between theory and experiment.

Abstract

The amplitude and phase of Shubnikov-de Haas oscillations have been analyzed in detail for two-dimensional electron gases subjected to a weak unidirectional periodic potential modulation. The amplitude is suppressed, accompanied by inversion of the phase, at the maximum bandwidth conditions at low magnetic fields. The suppression is gradually taken over by the enhancement with the increase of the magnetic fields. The suppression and the enhancement are attributable to the collisional and the diffusion contribution of the modulated potential to the conductivity, respectively, the former (the latter) being dominant at low (high) magnetic fields. A theoretical calculation that takes the two types of contributions into account shows semi-quantitative agreement with experimental traces.