电荷密度波相单层过渡金属二硫族化合物中超导电性的第一性原理研究

电荷密度波与超导竞争共存是凝聚态物理领域一经典话题，但机理尚不明确。研究它们之间的相互作用，不仅可揭示其中的物理，还有助于理解高温超导的形成。据报导，单层过渡金属二硫族化合物（单层2H-NbSe2、2H-TaS2、2H-TaSe2）有相似的晶格和电子结构，却表现出不同的电荷密度波与超导的竞争关系，相关研究尚在起步阶段。.本项目以第一性原理计算为研究手段，以电荷密度波相单层过渡金属二硫族化合物为主要研究对象，拟开展如下探索：1）电荷密度波对超导电性的影响及机制；2）应力、电荷掺杂对超导电性的调控及机制；3）自旋轨道耦合效应对超导电性的影响及机制。.本项目从第一性原理角度，细致地研究上述体系中电声耦合及超导电性。一方面有助于更准确、系统地理解这类多关联体系的相图，为理解电荷密度波与超导竞争共存这一经典话题提供参考。另一方面揭示应力、电荷掺杂对体系超导电性调控的机制，有助于深入理解部分实验现象。

The competition and coexistence between charge-density wave (CDW) and superconductivity is a longstanding issue in condense matter physics, but the mechanism still remains investigation. The study of the interplay between the above two orders, on one hand, may reveal the underlying physics therein, on the other hand, may help to understand the formation of high-temperature superconductivity. According to the latest reports, monolayer transition-metal dichalcogenides (monolayer 2H-NbSe2, 2H-TaS2, 2H-TaSe2), though with similar crystal and electronic structures, were found to exhibit different competition relationships between CDW and superconductivity, which calls for further studies. ..The present project mainly focuses on the monolayer transition-metal dichalcogenides in CDW states using first-principles methods. In detail, the project covers the following topics. 1) The influence of the CDW on the superconductivity and the corresponding mechanism. 2) The influence of strain engineering and charge doping on the superconductivity and the corresponding mechanism. 3) The influence of spin-orbit coupling effect on the superconductivity and the corresponding mechanism...In summary, this project investigates the electron-phonon coupling and superconducting properties of the monolayer transition-metal dichalcogenides of CDW phases in detail from the perspective of first principles calculations. On one hand, the research may help to get better understanding of the rich phase diagrams in these multi-correlated systems and provide useful information to the classic issue regarding the competition and coexistence between CDW and superconductivity. On the other hand, the research may reveal the nature of the influence of strain engineering and charge doping on the superconducting properties of the systems, which may help to obtain a deeper understanding about some experimental observations.