Evidence for quasi-classical transport of composite fermions in an inhomogeneous effective magnetic field

Abstract

We report on transverse magnetic focusing experiments in arrays of equidistant constrictions with centre-to-centre constriction spacings L varying from 500 nm to in the vicinity of the Landau level filling factor of a two-dimensional electron system. Provided the composite fermion mean free path is comparable to L, focusing is observed for both effective magnetic field directions. The non-uniform electron distribution with a saddle point in the middle of each constriction, and the associated inhomogeneous effective magnetic field for the composite fermions, invokes characteristic differences in the composite fermion focusing spectra compared with the electron focusing spectra near zero magnetic field. These changes are well predicted by quasi-classical calculations of the composite fermion dynamics in the corresponding potential landscape.