Velocity shift of surface acoustic waves due to interaction with composite fermions in a modulated structure

TL;DR

This paper investigates how periodic density modulations affect surface acoustic wave propagation in a 2D electron gas near Landau level filling, revealing significant velocity shifts explained by composite fermion theory.

Contribution

It demonstrates that small density modulations cause large SAW velocity shifts, supporting the composite fermion model and aligning with experimental resistivity data.

Findings

A few percent modulation causes a large peak in SAW velocity shift.

Theoretical predictions match recent experimental data.

DC resistivity results support the composite fermion interpretation.

Abstract

We study the effect of a periodic density modulation on surface acoustic wave (SAW) propagation along a 2D electron gas near Landau level filling $\nu=1/2$. Within the composite fermion theory, the problem is described in terms of fermions subject to a spatially modulated magnetic field and scattered by a random magnetic field. We find that a few percent modulation induces a large peak in the SAW velocity shift, as has been observed recently by Willett et al. As further support of this theory we find the dc resistivity to be in good agreement with recent data of Smet et al.