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arXiv 1603.04263cond-mat.str-el
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三维拓扑量子相变的强关联效应

Strong Correlation Effects on Topological Quantum Phase Transitions in Three Dimensions

A. Amaricci, J. C. Budich, M. Capone, B. Trauzettel, G. Sangiovanni

摘要:

利用动力学平均场论,研究了短程电子-电子相互作用在三维拓扑绝缘体的典范模型中的作用,并着重于非磁有序解。非相互作用的带结构是由一个质量项M,其值区分三个不同的绝缘相,平凡的带绝缘体和两个不同的拓扑非平凡的阶段。我们描述了不同相之间的转变作为局部库仑排斥U的函数的演化,并发现U-M相图对局部Hund交换耦合J的值有显著的依赖性。然而,无论J的值如何,随着平凡带绝缘体和拓扑绝缘体之间的拓扑转变线的演化,我们找到了将连续跃迁与一阶跃迁分开的U的临界值。当洪德耦合显著时,莫特绝缘体稳定在大U。在Mott转变附近,我们观察到一个异常的“Mott样”强拓扑绝缘态的出现。

英文摘要:

We investigate the role of short-ranged electron-electron interactions in a paradigmatic model of three dimensional topological insulators, using dynamical mean-field theory and focusing on non magnetically ordered solutions. The non-interacting band-structure is controlled by a mass term M, whose value discriminates between three different insulating phases, a trivial band insulator and two distinct topologically non-trivial phases. We characterize the evolution of the transitions between the different phases as a function of the local Coulomb repulsion U and find a remarkable dependence of the U -M phase diagram on the value of the local Hund's exchange coupling J. However, regardless the value of J, following the evolution of the topological transition line between a trivial band insulator and a topological insulator, we find a critical value of U separating a continuous transition from a first-order one. When the Hund's coupling is significant, a Mott insulator is stabilized at large U . In proximity of the Mott transition we observe the emergence of an anomalous "Mott-like" strong topological insulating state.

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