Nonlinear Absorption of Surface Acoustic Waves by Composite Fermions.

摘要

Absorption of surface acoustic waves by a two-dimensional electron gas in a perpendicular magnetic field is considered. The structure of such system at the filling factor nu close to 1/2 can be understood as a gas of composite fermions. It is shown that the absorption at nu = 1/2 can be strongly nonlinear while small deviation from 1/2 will restore the linear absorption. Study of nonlinear absorption allows one to determine the force acting upon the composite fermions from the acoustic wave at turning points of their trajectories.