Frequency-dependent magnetotransport in a two-dimensional magnetic modulation system

We analyze the dynamics of a charged particle moving in the presence of spatially modulated magnetic fields, motivated by recent transport experiments by Ye et al. (Phys. Rev. Lett. 74 (1995) 3013). We show from Poincare surfaces of section that the ratio of pinned orbits to chaotic orbits depends strongly on the energy and the structure parameters. We present a complete characterization of the dynamical behavior of such structures, and calculate the magnetoconductivity using a classical Kubo formula. We investigate the contribution to the conductivity from pinned and runaway orbits. Although the DC conductivity of the system depends strongly on the ratio of pinned to runaway trajectories, the high-frequency response reflects the topology of the different orbits. (C) 1998 Elsevier Science B.V. All rights reserved.