Magnetic focusing of composite fermions in a cavity array

Abstract

The magnetoresistance Rxx was investigated in arrays of abutted square cavities with lengths L ranging from 500 nm to 1.2 ìm near filling factor í = 1/2. Maxima in Rxx occur for effective magnetic field values satisfying the magnetic focusing condition between the cavity spacing and the cyclotron radius of composite fermions, also for the effective magnetic field direction when composite fermions are deflected in the direction opposite to that of electrons. The experimental data are compared with simulation results based on a quasiclassical dynamics of composite fermions in soft potentials.