Dynamical Kohn Anomaly in Surface Acoustic Wave Response in Quantum Hall Systems Near $\nu =1/2$

Abstract

The dynamical analog of the Kohn Anomaly image of the Fermi Surface is demonstrated for the response functions to the surface acoustic waves in Quantum Hall Systems near $\nu =1/2$. Kinks appear in the velocity shift $Deltas/s$ and attenuation coefficient $\Gamma$. The effect is considerably enhanced under periodic modulation and should be observable.

5 pages, 2 figures, the published version