Local geometry of the Fermi surface and magnetoacoustic response of two-dimensional electron systems in strong magnetic fields

摘要

A semiclassical theory for magnetotransport in a quantum Hall system near filling factor nu = 1/2 based on the composite fermion physical picture is used to analyse the effect of local flattening of the composite fermion Fermi surface (CF-FS) upon magnetoacoustic oscillations. 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 will be revealed in experiments, and will be used in further studies of the shape and symmetries of the CF-FS. The main conclusions reported here could be applied to analyse magnetotransport in quantum Hall systems at higher filling factors nu = 3/2 and 5/2 for a Fermi-liquid-like state of the system.