Klöckner C, Karrasch C, Kennes D M
Technische Universität Braunschweig, Institut für Mathematische Physik, Mendelssohnstrae 3, 38106 Braunschweig, Germany.
Institut für Theorie der Statistischen Physik, RWTH Aachen University and JARA-Fundamentals of Future Information Technology, 52056 Aachen, Germany.
Phys Rev Lett. 2020 Oct 2;125(14):147601. doi: 10.1103/PhysRevLett.125.147601.
We employ a novel, unbiased renormalization-group approach to investigate nonequilibrium phase transitions in infinite lattice models. This allows us to address the delicate interplay of fluctuations and ordering tendencies in low dimensions out of equilibrium. We study a prototypical model for the metal to insulator transition of spinless interacting fermions coupled to electronic baths and driven out of equilibrium by a longitudinal static electric field. The closed system features a Berezinskii-Kosterlitz-Thouless transition between a metallic and a charge-ordered phase in the equilibrium limit. We compute the nonequilibrium phase diagram and illustrate a highly nonmonotonic dependence of the phase boundary on the strength of the electric field: for small fields, the induced currents destroy the charge order, while at higher electric fields it reemerges due to many-body Wannier-Stark localization physics. Finally, we show that the current in such an interacting nonequilibrium system can counter-intuitively flow opposite to the direction of the electric field. This nonequilibrium steady state is reminiscent of an equilibrium distribution function with an effective negative temperature.
我们采用一种新颖的、无偏重整化群方法来研究无限晶格模型中的非平衡相变。这使我们能够处理低维非平衡态下涨落与有序倾向之间的微妙相互作用。我们研究了一个原型模型，该模型描述了无自旋相互作用费米子与电子库耦合，并由纵向静电场驱动至非平衡态时的金属 - 绝缘体转变。在平衡极限下，该封闭系统在金属相和电荷有序相之间存在贝雷津斯基 - 科斯特利茨 - Thouless 转变。我们计算了非平衡相图，并说明了相边界对电场强度的高度非单调依赖性：对于小电场，感应电流会破坏电荷序，而在较高电场下，由于多体万尼尔 - 斯塔克局域化物理机制，电荷序会重新出现。最后，我们表明，在这样一个相互作用的非平衡系统中，电流会出人意料地流向与电场方向相反的方向。这种非平衡稳态让人联想到具有有效负温度的平衡分布函数。
