Magnetic Focusing of Composite Fermions through Arrays of Cavities

The magnetoresistance $R_{\mathrm{xx}}$ was investigated in arrays of abutted square cavities with lengths $L$ ranging from $500\mathrm{nm}$ to $1.2\mu \mathrm{m}$ near filling factor $\nu =1\mathrm{}/2$. Maxima in $R_{\mathrm{xx}}$ 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.