论文标题
通过电荷密度波转换的新兴拓扑超导体
Emergent Topological Superconductor by Charge Density Wave Transition
论文作者
论文摘要
多体不稳定性和拓扑物理学是凝结物理学的两个有吸引力的主题。在单个量子材料中探索这些现象之间的相互作用很有趣。在这里，以典型的电荷密度波（CDW）材料单层1H-NBSE $ _2 $为例，我们显示了动量依赖性的电子 - phonon耦合如何将CDW从$ 3 \ times3 $到$ 2 \ $ 2 \ $ 2 \ times 2 $相位。更有趣的是，我们发现在两个$ 2 \ times2 $ cdw阶段之一中，超导性和非平凡拓扑的共存，后者是由非零的z $ _2 $不变的，具有理想的狄拉克锥形状态在Fermi水平附近。同类型的CDW过渡诱导的拓扑超导体也已在单层1H-Tase $ _2 $中得到证实。我们的发现不仅揭示了通过CDW过渡引入非平凡拓扑的独特而通用的方法，而且还提供了一个理想的平台来通过电子掺杂来调节不同的量子阶，从而刺激了实验兴趣。
Many-body instabilities and topological physics are two attractive topics in condensed matter physics. It is intriguing to explore the interplay between these phenomena in a single quantum material. Here, using the prototypical charge density wave (CDW) material monolayer 1H-NbSe$_2$ as an example, we show how momentum-dependent electron-phonon coupling drives the CDW transition from $3\times3$ to $2\times2$ phase under electron doping. More interestingly, we find the coexistence of superconductivity and nontrivial topology in one of the two $2\times2$ CDW phases, the latter of which is identified by the nonzero Z$_2$ invariant with ideal Dirac cone edge states near the Fermi level. A similar CDW transition-induced topological superconductor has also been confirmed in monolayer 1H-TaSe$_2$. Our findings not only reveal a unique and general method to introduce nontrivial topology by CDW transition, but also provide an ideal platform to modulate different quantum orders by electron doping, thus stimulating experimental interest.
