Geometric Resonance of Composite Fermion Cyclotron Orbits with a Fictitious Magnetic Field Modulation

In dc transport measurements of two-dimensional electron systems containing a small charge density modulation in one direction, resonance structure in resistance is observed near filling factor $\frac{1}{2}$. For a sufficiently well-controlled modulation amplitude, the magnetic field positions of these distinct resistance minima are consistent with values for a periodic magnetic modulation as predicted in a Chern-Simons fermion picture of $\nu =\frac{1}{2}$.