On the Theory of a New Maximum Observed in dc Transport in Modulated Quantum Hall Systems Near ν=1/2

We propose a theory for the new maximum recently observed by Willett et al [1] in the longitudinal magnetoresistance of a weakly modulated two-dimensional electron gas (2DEG) near filling factor \nu =1/2 for the current driven along the modulation lines. The maximum is superimposed upon a new resonance structure. This occurs due to the geometric resonance of composite fermion cyclotron orbits with the period of modulation of the effective magnetic field. We propose here a semiquantitative theory of the dc magnetotransport in a modulated 2DEG near one half filling. Our analysis is based on the Boltzmann transport equation and it enables us to obtain this maximum which was neither observed nor predicted previously.