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

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 $ν= 1/2$. Kinks appear in the velocity shift $Delta s/s$ and attenuation coefficient $Γ$. The effect is considerably enhanced under periodic modulation and should be observable.