异质界面中的量子相变和无序效应的动力学平均场理论研究

项目名称： 异质界面中的量子相变和无序效应的动力学平均场理论研究

项目编号： No.11474023

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 宋筠

作者单位： 北京师范大学

项目金额： 81万元

中文摘要： 金属氧化物异质结构新型材料能呈现出迥异于其块体材料诸多的新奇量子特性，在非磁性绝缘体构成的LaAlO/SrTiO界面上业已发现二维电子液体态、铁磁态和超导态，且铁磁与超导竟会共存，这些奇特的现象急待合理的理论解释。因界面上屏蔽效应减弱而导致了电子关联显著增强，而Rashba自旋-轨道耦合又会引起平移不变性的破缺，另外无序对量子相变的影响也是不应被完全忽视的，因此理论研究的难度很大。本项目计划发展的实空间晶胞动力学平均场理论是一个研究异质界面的最有效的理论方法，这一方法不仅能够有效地处理电子间的相互作用，而且也能够合理地考虑空间的涨落及平移不变性的破缺。我们拟从新奇的量子态和量子相变入手，通过研究各种重要因素之间的相互关系和共同效应来揭示输运现象的微观机制，为实现界面新奇量子相的调控供理论依据。

中文关键词： 异质结构；动力学平均场理论；自旋轨道耦合；金属绝缘体相变；无序效应

英文摘要： Heterointerfaces between metal oxides have been shown to exhibit some interesting properties which are not seen in the bulk materials. A variety of unusual electronic phases, such as two-dimensional electron liquid state, ferromagnetic order and superconducting phase have been found at the interface between two nonmagnetic insulators LaAlO3 and SrTiO3, where superconductivity can even coexist with ferromagnetism. In the theoretical studies of LaAlO/SrTiO interface, we should take into consideration the following aspects: the strong electronic correlations introduced by the reduction of the screening effect at interfaces, the broken translation invariance caused by Rashba spin-orbital coupling, and the effect of disorder on the quantum phase transitions. In this project, the real-space cluster dynamical mean-field theory is going to be set up by extending the cellular dynamical mean-field theory to real space. As a result, the strong electronic correlations, the spatial fluctuation and the broken translation invariance can be treated on an equal footing. To reveal the mechanism of transport properties at the heterointerfaces of metal oxides, we will concentrate on the interplay between some important factors and their effects on the quantum phase transitions, providing theoretical bases for manipulating the quantum phases at heterointerfaces.

英文关键词： Heterostructure;Cluster Dynamical Mean-Field Theory;Spin-Orbital Coupling;Metal-Insulator Transition;Effect of Disorder