对大量NbX2 (X = S和Se) 的CDW阶段的理论研究
Hongwei Du1, Zhenyi Jiang1, Jiming Zheng1
1Shaanxi Key Laboratory for Theoretical Physics Frontiers, Institute of Modern Physics, Northwest University, Xi'an 710069, China.
Physical chemistry chemical physics : PCCP
|January 3, 2024
概括
这项研究理论上预测了大量2H-NbS2中更稳定的电荷密度波 (CDW) 阶段,解决了它与超导的长期共存. 建议在特定的充电注入水平下进行实验观察.
科学领域:
- 凝聚物质物理学 凝聚物质物理学
- 材料科学 材料科学 材料科学
- 固态物理 固态物理
背景情况:
- 大多数二维过渡金属化物表现出共存的超导和电荷密度波 (CDW) 阶段.
- 大量2H-NbS2是一个例外,缺乏CDW阶段的实验证据,尽管自1975年以来一直有兴趣.
- 对于CDW相的热力学稳定性,特别是在电荷注入下,仍然是一个悬而未决的问题.
研究的目的:
- 理论上研究CDW阶段的存在和稳定性,包括2H-NbS2和2H-NbSe2.
- 解决这些材料中CDW和超导相共存的长期问题.
- 预测CDW阶段的实验观测条件,大批量2H-NbS2.2.
主要方法:
- 调和声波软化理论和第一原则计算的应用.
- 对理论CDW散装配置 (TC为2H-NbS2,TT为2H-NbSe2) 的分析.
- 状态密度 (DOS) 和带结构的计算,以确定载体类型和过渡.
主要成果:
- 理论上预测了更稳定的CDW配置,其中部分伪能量差距为散装2H-NbS2和2H-NbSe2.
- 在CDW阶段的伪间隙比率与超导阶段的2H-NbX2 (X = S, Se) 大量相匹配.
- 在CDW形成时预测2H-NbS2的p型载体和2H-NbSe2的 p-到n型交替载体;在2H-NbSe2.2中观察到Lifshitz过渡.
结论:
- 理论上,CDW相对于2H-NbS2散装的金属相要稳定得多,尤其是在充电注入的情况下.
- CDW阶段应该与超导状态并存,而不是金属阶段,在临界温度以下的2H-NbS2中.
- 预计在0.5e/Nb18S36.6的充电注入时,CDW阶段的实验观测将得到加强.
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