Quantum transport, bifurcations, and emergent dynamic phases in strongly driven nanostructures

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This theoretical project addresses two spectacular nonequilibrium phenomena in the low-temperature magnetotransport of irradiated two-dimensional electron systems: microwave-induced resistance oscillations (MIRO) and associated zero resistance states (ZRS). Recent time-resolved measurements of spontaneous voltages provided first direct evidence for the domain nature of ZRS. At the same time, these experiments revealed slow temporal dynamics (including self-oscillations of the order parameter and the regime of nearly periodic switching between domain configurations of the opposite polarity) not expected from the existing theory predicting static domains. A mechanism of slow dynamics that gives a plausible explanation for the rich dynamics of ZRS was recently proposed by the principal investigator and will be comprehensively studied in this project. Joint efforts with leading experimental groups promise significant advances in the understanding of several competing dynamic and static regimes of the ZRS. While until recently MIRO and ZRS were only observed in high-mobility AlGaAs/GaAs heterostructures, novel experimental techniques such as local pulsed terahertz-laser excitation as well as rapid technological advances made feasible their observation in several different material systems (currently including p-type Si/SiGe, ZnO/MnZnO, and electrons on surface of liquid He). Further combined theoretical and experimental studies in this direction should (i) provide a distinction between universal and material/geometry dependent properties of these phenomena; (ii) establish generic conditions for their observation; (iii) shed light on remaining controversial issues such as the striking polarization immunity of MIRO; (iv) provide access to the material parameters not accessible from standard transport measurements.