Barnett Ryan L, Polkovnikov Anatoli, Demler Eugene, Yin Wei-Guo, Ku Wei
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Phys Rev Lett. 2006 Jan 20;96(2):026406. doi: 10.1103/PhysRevLett.96.026406.
An unexpected feature common to 2H transition metal dichalcogenides ( 2H TMDs) is revealed with a first-principles Wannier function analysis of the electronic structure of the prototype 2H TaSe2: The low-energy Ta "5d(z2)" bands governing the physics of a charge-density wave (CDW) is dominated by hopping between next-nearest neighbors. With this motivation we develop a minimal effective model for the CDW formation, in which the unusual form of the hopping leads to an approximate decoupling of the three sublattices. In the CDW phase one sublattice remains undistorted, leaving the bands associated with it ungapped everywhere in the Fermi surface, resolving the long-standing puzzle of the coexistence of gapless excitations and commensurate CDW in the 2H TMDs.
通过对原型2H-TaSe₂的电子结构进行第一性原理的万尼尔函数分析，揭示了二硫化物过渡金属（2H-TMDs）常见的一个意外特征：控制电荷密度波（CDW）物理性质的低能Ta “5d(z2)” 能带主要由次近邻之间的跳跃主导。基于此，我们开发了一个用于CDW形成的最小有效模型，其中跳跃的异常形式导致三个子晶格近似解耦。在CDW相中，一个子晶格保持不变形，使得与其相关的能带在费米面处处无带隙，解决了2H-TMDs中无隙激发与相称CDW共存的长期难题。
