论文标题

耗散性系统的非平衡效应

Non-equilibrium Effects in Dissipative Strongly Correlated Systems

论文作者

Li, Jiajun

论文摘要

当通过外场将强相关系统驱动到平衡时,新的物理学就会产生。物理性质的急剧变化(例如电导率)在高电场下的强相关材料中经验观察到。尤其是,电场驱动的金属绝缘体过渡是多种材料中的电阻切换效果,例如vo $ _2 $,v $ _2 $ o $ $ _3 $和其他过渡金属氧化物。为了令人满意地解释现象学及其基本机制,需要以显微镜对相互作用电子的耗散耗散晶格系统进行建模。在本论文中,我们开发了一种系统的方法,通过非平衡绿色的功能和动力学平均场理论为耗散晶格系统建模非平衡稳态。我们首先建立了一个“最小模型”,以在非相互作用的耗散电子晶格中制定强场传输。该模型完全可溶于讨论能量耗散和稳态特性。然后将形式主义与动态平均场理论结合使用,以提供一个系统的框架,描述相关材料的非平衡稳态。我们使用形式主义研究石墨烯中相关材料,莫特绝缘子和狄拉克电子的强场传输特性。我们集中于电阻转换的微观描述。特别令人感兴趣的是动态相变过程中的细丝形成,这是由于耗散与莫特物理学之间微妙的相互作用而被解释的。我们还将检查$ IV $特征,尤其是石墨烯中狄拉克电子的当前饱和度。 ARXIV版本已通过较小的修改和更正进行了更新。

Novel physics arises when strongly correlated system is driven out of equilibrium by external fields. Dramatic changes in physical properties, such as conductivity, are empirically observed in strongly correlated materials under high electric field. In particular, electric-field driven metal-insulator transitions are well-known as the resistive switching effect in a variety of materials, such as VO$_2$, V$_2$O$_3$ and other transition metal oxides. To satisfactorily explain both the phenomenology and its underlying mechanism, it is required to model microscopically the out-of-equilibrium dissipative lattice system of interacting electrons. In this thesis, we developed a systematic method of modeling non-equilibrium steady states for dissipative lattice systems by means of Non-equilibrium Green's function and Dynamical Mean Field Theory. We firstly establish a "minimum model" to formulate the strong-field transport in non-interacting dissipative electron lattice. This model is exactly soluble and convenient for discussing energy dissipation and steady-state properties. The formalism is then combined with Dynamical Mean Field Theory to provide a systematic framework describing the nonequilibrium steady-state of correlated materials. We use the formalism to study the strong-field transport properties of correlated materials, Mott insulators and Dirac electrons in graphene. We concentrate on the microscopic description of resistive switching. Of particular interest is the filament formation during the dynamical phase transition, which has been interpreted as a result of the delicate interplay between dissipation and Mott physics. We will also examine $IV$ characteristics and particularly the current saturation of Dirac electrons in graphene. The arXiv version has been updated with minor modifications and corrections.

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