2 research outputs found
Frequency-dependent magnetotransport and particle dynamics in magnetic modulation systems
We analyze the dynamics of a charged particle moving in the presence of
spatially-modulated magnetic fields. From Poincare surfaces of section and
Liapunov exponents for characteristic trajectories we find that the fraction of
pinned and runaway quasiperiodic orbits {\em vs}. chaotic orbits depends
strongly on the ratio of cyclotron radius to the structure parameters, as well
as on the amplitude of the modulated field. We present a complete
characterization of the dynamical behavior of such structures, and investigate
the contribution to the magnetoconductivity from all different orbits using a
classical Kubo formula. Although the DC conductivity of the system depends
strongly on the pinned and runaway trajectories, the frequency response
reflects the topology of all different orbits, and even their unusual temporal
behavior.Comment: Submitted to PRB - 14 figure files - REVTEX tex
Anisotropic scattering and quantum magnetoresistivities of a periodically modulated 2D electron gas
We calculate the longitudinal conductivities of a two-dimensional
noninteracting electron gas in a uniform magnetic field and a lateral electric
or magnetic periodic modulation in one spatial direction, in the quantum
regime. We consider the effects of the electron-impurity scattering anisotropy
through the vertex corrections on the Kubo formula, which are calculated with
the Bethe-Salpeter equation, in the self-consistent Born approximation. We find
that due to the scattering anisotropy the band conductivity increases, and the
scattering conductivities decrease and become anisotropic. Our results are in
qualitative agreement with recent experiments.Comment: 19 pages, 8 figures, Revtex, to appear in Phys. Rev.