Local Geometry of the Fermi Surface and Magnetoacoustic Responce of Two-Dimensional Electron Systems in Strong Magnetic Fields

TL;DR

This paper develops a semiclassical theory to analyze how local flattening of the Composite Fermion Fermi surface affects magnetoacoustic responses in quantum Hall systems, predicting observable changes in surface acoustic wave oscillations.

Contribution

It introduces a model linking local Fermi surface geometry to magnetoacoustic effects, enabling new insights into Fermi surface shape and symmetries in quantum Hall systems.

Findings

Local Fermi surface flattening influences SAW velocity shift and attenuation.

Predicted oscillation changes are detectable in experiments.

Results applicable to higher filling factors like ν=3/2, 5/2.

Abstract

A semiclassical theory for magnetotrasport in a quantum Hall system near filling factor $\nu = 1/2 $ based on the Composite Fermions physical picture is used to analyze the effect of local flattening of the Composite Fermion Fermi surface (CF-FS) upon magnetoacoustic oscllations. We report on calculations of the velocity shift and attenuation of a surface acoustic wave (SAW) which travels above the two-dimensional electron system, and we show that local geometry of the CF-FS could give rise to noticeable changes in the magnitude and phase of the oscillations. We predict these changes to be revealed in experiments, and to be used in further studies of the shape and symmetries of the CF-FS. Main conclusions reported here could be applied to analyze magnetotransport in quantum Hall systems at higher filling factors $ \nu = 3/2, 5/2 $ provided the Fermi-liquid-like state of the system.