论文标题

光电莫特绝缘子的非平衡稳态理论

Nonequilibrium steady-state theory of photodoped Mott insulators

论文作者

Li, Jiajun, Eckstein, Martin

论文摘要

在激光兴奋的莫特绝缘子中广泛观察到光电型状态,在激光兴奋的莫特绝缘子中,电荷激发很快就会产生,并且可以在外部驾驶的持续时间之外存在。尽管进行了富有成果的实验探索,但对微观模型的理论研究面临着同时处理指数分开的时间尺度的挑战,尤其是在多波段系统中,在多波段系统中,长期行为通常远远超出了最先进的数值工具的范围。在这里,我们通过使用开放系统设置引入光电型莫特绝缘子的稳态描述来解决这一困难,在该设置中,光电型系统通过弱外部驾驶稳定为非平衡稳态(NESS)。利用平稳性,我们使用稳态动态平均场理论(DMFT)实施并讨论了有效的数值工具的细节,并结合了非交叉近似(NCA)。我们证明,这些固定的光载体状态具有相同的瞬态对应物,同时可以通过合理的计算工作来解决。此外,它们只能通过很少的物理量(包括有效温度和电荷激发密度)来参数化,这证实了光电型状态的普遍性确实与激发协议无关。作为第一个应用,我们考虑了带有交织的自旋和轨道订购的两种带哈伯德模型中的固定光解码状态,并从先前的研究中找到了一个未知的隐藏阶段家族,这意味着相互交织订单的放松状态明显未开发。

Photodoped states are widely observed in laser-excited Mott insulators, in which charge excitations are quickly created and can exist beyond the duration of the external driving. Despite the fruitful experimental explorations, theoretical studies on the microscopic models face the challenge to simultaneously deal with exponentially separated time scales, especially in multi-band systems, where the long-time behaviors are often well beyond the reach of state-of-the-art numerical tools. Here, we address this difficulty by introducing a steady-state description of photodoped Mott insulators using an open-system setup, where the photodoped system is stabilized as a non-equilirium steady-state (NESS) by a weak external driving. Taking advantage of the stationarity, we implement and discuss the details of an efficient numerical tool using the steady-state Dynamical Mean-Field Theory (DMFT), combined with the non-crossing approximation (NCA). We demonstrate that these stationary photodoped states exhibit the same properties of their transient counterparts, while being solvable with reasonable computational efforts. Furthermore, they can be parametrized by just few physical quantities, including the effective temperature and the density of charge excitations, which confirms the universal nature of photodoped states indeed independent of the excitation protocols. As a first application, we consider the stationary photodoped states in a two-band Hubbard model with intertwined spin-and-orbital ordering and find a family of hidden phases unknown from the previous studies, implying an apparently unexplored time regime of the relaxation of the intertwined orders.

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