arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1602.00618cond-mat.str-elcond-mat.mes-hall
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拓扑绝缘体超薄膜多层膜中Weyl半金属的手征磁导率和表面态

Chiral magnetic conductivity and surface states of Weyl semimetals in topological insulator ultra-thin film multilayer

S. A. Owerre

摘要:

我们研究了一个超薄的拓扑绝缘体(TI)多层薄膜作为三维(3D)Weyl半金属模型。我们引入隧穿参数$t_S$,$t_\perp$,和$t_D$,其中前两个参数耦合层相同的薄膜在小和大的动量,和后一个参数耦合相邻的薄膜层沿$z$方向。计算了体系各拓扑相的Chern数,发现对于$t_S,t_D>0$,随着体系从Weyl半金属相向绝缘相转变,隧道参数$t_\perp$由正向负变化.我们进一步研究了在含时磁场存在下系统的手征磁效应。我们计算的手征磁导率的低温依赖性,并表明,它捕获三个不同的阶段的系统分离的高原。此外,我们提出并研究了卟啉薄膜的三维晶格模型,卟啉薄膜是一种已知支持拓扑Frenkel激子边缘态的有机材料。我们表明,该模型具有三维外尔半金属相,也支持二维外尔半金属相。进一步证明了该模型恢复了拓扑绝缘体薄膜多层膜中三维Weyl半金属的模型。从而为模拟拓扑绝缘体薄膜多层膜中的三维Weyl半金属铺平了道路。我们得到了3D模型中的表面态(费米弧)和2D模型中的手征边缘态,并分析了它们的拓扑性质。

英文摘要:

We investigate an ultra-thin film of topological insulator (TI) multilayer as a model for a three-dimensional (3D) Weyl semimetal. We introduce tunneling parameters $t_S$, $t_\perp$, and $t_D$, where the former two parameters couple layers of the same thin film at small and large momenta, and the latter parameter couples neighbouring thin film layers along the $z$-direction. The Chern number is computed in each topological phase of the system and we find that for $t_S,t_D>0$, the tunneling parameter $t_\perp$ changes from positive to negative as the system transits from Weyl semi-metallic phase to insulating phases. We further study the chiral magnetic effect (CME) of the system in the presence of a time dependent magnetic field. We compute the low-temperature dependence of the chiral magnetic conductivity and show that it captures three distinct phases of the system separated by plateaus. Furthermore, we propose and study a 3D lattice model of Porphyrin thin film, an organic material known to support topological Frenkel exciton edge states. We show that this model exhibits a 3D Weyl semi-metallic phase and also supports a 2D Weyl semi-metallic phase. We further show that this model recovers that of 3D Weyl semimetal in topological insulator thin film multilayer. Thus, paving the way for simulating a 3D Weyl semimetal in topological insulator thin film multilayer. We obtain the surface states (Fermi arcs) in the 3D model and the chiral edge states in the 2D model and analyze their topological properties.

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