University
of Toronto
Physics Department
Condensed Matter and Quantum Optics
MONDAY SEMINAR
University
of Toronto
| Speaker : | DR. ADAM DURST
Yale University |
| Topic : | Radiation-Induced Magnetoresistance Oscillations in a 2D Electron Gas |
| Time : | Monday September 22, 2003 at 12:00 noon |
| Place : | Room MP408, Burton Tower, 60 St. George Street / 255 Huron Street |
Abstract
Recent measurements of a 2D electron gas subjected to microwave radiation
reveal a magnetoresistance with an oscillatory dependence on the ratio of
radiation frequency to cyclotron frequency. We perform a diagrammatic
calculation and find radiation-induced resistivity oscillations with the correct
period and phase. Results are explained via a simple picture of current induced
by photo-excited disorder-scattered electrons. The oscillations increase with
radiation intensity, easily exceeding the dark resistivity and resulting in
negative-resistivity minima. At high intensity, we identify additional features,
likely due to multi-photon processes, which have yet to be observed
experimentally. Andreev, Aleiner, and Millis (cond-mat/0302063) have shown that
the negative resistivity state is unstable, which leads to a domain structure in
the current distribution. This causes the resistivity to saturate at zero rather
than going negative, in agreement with experiment.
Local Host: Yong Baek Kim
(416-978-5193) 