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arXiv 1206.0979cond-mat.str-el
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蜂窝晶格上的竞争拓扑相和Kondo绝缘相

Competing topological and Kondo insulator phases on a honeycomb lattice

Xiao-Yong Feng, Jianhui Dai, Chung-Hou Chung, Qimiao Si

摘要:

我们研究了蜂窝晶格中巡游电子的自旋-轨道相互作用与它们的近藤耦合之间的竞争。我们发现,在半填充模型显示拓扑和Kondo绝缘体之间的量子相变在非零Kondo耦合。在近藤屏蔽的情况下,调整电子浓度可以导致新的拓扑绝缘体相。结果表明,重费米子相图包含一个新的区域,拓扑态、近藤相干态和磁态相互竞争,该区域可能与含$5d$传导电子的近藤晶格系统特别相关.最后,我们讨论了我们的研究结果的背景下,最近的实验对钐$_6$牵连的拓扑绝缘体的表面状态,以及现有的实验在钐$_6$的压力下,在CeNiSn的化学压力下的相变。

英文摘要:

We investigate the competition between the spin-orbit interaction of itinerant electrons and their Kondo coupling with local moments densely distributed on the honeycomb lattice. We find that the model at half-filling displays a quantum phase transition between topological and Kondo insulators at a nonzero Kondo coupling. In the Kondo-screened case, tuning the electron concentration can lead to a new topological insulator phase. The results suggest that the heavy-fermion phase diagram contains a new regime with a competition among topological, Kondo-coherent and magnetic states, and that the regime may be especially relevant to Kondo lattice systems with $5d$-conduction electrons. Finally, we discuss the implications of our results in the context of the recent experiments on SmB$_6$ implicating the surface states of a topological insulator, as well as the existing experiments on the phase transitions in SmB$_6$ under pressure and in CeNiSn under chemical pressure.

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