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arXiv 1609.08618cond-mat.str-elcond-mat.mes-hall
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在低维平带中实现拓扑表面态

Realizing topological surface states in a lower-dimensional flat band

Andrew C. Potter, Chong Wang, Max A. Metlitski, Ashvin Vishwanath

摘要:

对称性保护拓扑相的反常表面态通常被认为只可能与高维拓扑体相结合。然而,它最近已经意识到,一类异常的SPT表面状态可以实现在相同的维度,如果对称性被允许在一个非本地的方式。一个例子是粒子-空穴对称半填充朗道能级,它有效地实现了3D手性拓扑绝缘体(AIII类)的反常表面态。还讨论了狄拉克复合费米子的对偶描述。在这里,我们探讨这些结构的多组分量子霍尔态的推广。我们的结果包括一个对偶映射的双层的情况下,复合玻色子与Kramers简并和粒子空穴对称整数量子霍尔态的可能性时,组件的数量是8的倍数。接下来,我们通过半填充其他类拓扑带和施加粒子空穴对称性来进一步扩展。当应用于时间反演不变的拓扑绝缘体,我们实现了不同的手征类(CII)拓扑表面状态。值得注意的是,半填充3D TI带允许实现否则不可接近的4D拓扑绝缘体的表面,其支持异常3D狄拉克锥。构造了与三维狄拉克锥等价的表面拓扑序(从全局反常的观点来看),并与Witten的SU(2)反常建立了联系。这些观测结果对于拓扑表面态和没有费米子加倍的狄拉克费米子的数值模拟也是有用的。

英文摘要:

The anomalous surface states of symmetry protected topological (SPT) phases are usually thought to be only possible in conjunction with the higher dimensional topological bulk. However, it has recently been realized that a class of anomalous SPT surface states can be realized in the same dimension if symmetries are allowed to act in a nonlocal fashion. An example is the particle-hole symmetric half filled Landau level, which effectively realizes the anomalous surface state of a 3D chiral Topological Insulator (class AIII). A dual description in terms of Dirac composite fermions has also been discussed. Here we explore generalizations of these constructions to multicomponent quantum Hall states. Our results include a duality mapping of the bilayer case to composite bosons with Kramers degeneracy and the possibility of a particle hole symmetric integer quantum Hall state when the number of components is a multiple of eight. Next, we make a further extension by half filling other classes of topological bands and imposing particle hole symmetry. When applied to time-reversal invariant topological insulators we realize a different chiral class (CII) topological surface state. Notably, half-filling a 3D TI band allows for the realization of the surface of the otherwise inaccessible 4D topological insulator, which supports an anomalous 3D Dirac cone. Surface topological orders equivalent to the 3D Dirac cone (from the global anomaly standpoint) are constructed and connections to Witten's SU(2) anomaly are made. These observations may also be useful for numerical simulations of topological surface states and of Dirac fermions without fermion doubling.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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