Resistance effects due to magnetic guiding orbits

The Hall and magnetoresistance of a two-dimensional electron gas subjected to a magnetic field barrier parallel to the current direction is studied as a function of the applied perpendicular magnetic field. The recent experimental results of Nogaret et al. [Phys. Rev. Lett. 84, 2231 (2000)] for the magneto- and Hall resistance are explained using a semiclassical theory based on the Landauer-B\"uttiker formula. The observed positive magnetoresistance peak is explained as due to a competition between a decrease of the number of conducting channels as a result of the growing magnetic field, from the fringe field of the ferromagnetic stripe as it becomes magnetized, and the disappearance of snake orbits and the subsequent appearance of cycloidlike orbits.