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

这个理论项目研究了辐照二维电子系统低温磁输运中的两个壮观的非平衡现象：微波诱导的电阻振荡(MIRO)和相关的零电阻态(ZRs)。最近对自发电压的时间分辨测量为ZRs的区域性质提供了第一个直接证据。同时，这些实验揭示了慢的时间动力学(包括有序参数的自振荡和相反极性的磁区构型之间的近周期切换)，这是现有的预测静态磁区的理论所不期望的。最近，首席研究人员提出了一种慢动力学机制，它对ZRS丰富的动力学给出了合理的解释，并将在本项目中进行全面研究。与主要实验小组的共同努力有望在理解ZRS的几个相互竞争的动态和静态制度方面取得重大进展。虽然直到最近，MIRO和ZRS还只在高迁移率的AlGaAs/GaAs异质结中观察到，但新的实验技术，如局域脉冲太赫兹激光激发以及快速的技术进步，使得它们可以在几种不同的材料系统(目前包括p型Si/SiGe，ZnO/MnZnO，以及液体He表面的电子)中观察到。在这方面进一步的理论和实验相结合的研究应该：(1)区分这些现象的普遍性质和与材料/几何有关的性质；(2)确定观察这些现象的一般条件；(3)阐明仍然存在争议的问题，如MIRO的显著偏振免疫性；(4)提供从标准传输测量中无法获得的材料参数。

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.