Condensed-Matter Physics & Materials Science Seminar

We propose a unified quantum kinetic description of a family of
nonequilibrium magnetooscillations recently discovered in
high-mobility quantum Hall structures, including the microwave induced
resistance oscillations (MIRO), Hall-field induced RO (HIRO), and
phonon induced RO (PIRO). The magnetoresistivity is due to quantum
oscillations in the density of states in high Landau levels and is
governed by spectral and spatial resonances set by the cyclotron
frequency and the cyclotron diameter in various combinations with the
parameters of the external fields and phonons. External ac or dc
driving leads to local population inversion in the energy distribution
of electrons and modifies the scattering off impurities and phonons.
In particular, PIRO are shown to be very
sensitive to the applied direct current. In the supersonic regime,
where the Hall velocity exceeds the sound velocity, the
phonon-assisted conductivity remains finite at zero temperature, while below
the supersonic transition the oscillations get exponentially suppressed
at low temperature.
Quite interestingly, in the microwave-illuminated inhomogeneous 2D
electron gas, the photocurrent and photovoltage oscillations arise in
the absence of the external dc driving, due to nonequilibrium
violation of the Einstein relation between electrical current and
diffusion.