Structural phase transitions in two-dimensional Mo- and W-dichalcogenide monolayers
Structural phase transitions in two-dimensional Mo- and W-dichalcogenide monolayers
复制标题
DOI：
10.1038/ncomms5214
复制
发表时间：
2014-07-01
影响因子：
16.6
通讯作者：
Reed, Evan J.
中科院分区：
文献类型：
--
作者：
Duerloo, Karel-Alexander N.;Li, Yao;Reed, Evan J.
钼和钨二硫属化物化合物具有二维单层形式，在一个重要方面与石墨烯不同：它可能具有多个晶体结构。其中一些单分子层表现出令人着迷的暗示，即人们对结构金属到绝缘体的转变知之甚少，并且可能具有较长的亚稳态寿命。如果可控的话，这种转变可以为石墨烯以外的单层材料带来令人兴奋的新应用空间。在这里，我们发现机械变形提供了在这些单层材料的半导体和金属晶体结构之间切换热力学稳定性的途径。基于最先进的密度泛函和混合 Hartree-Fock/密度泛函计算（包括振动能量校正），我们发现 MoTe2 是一种出色的候选相变材料。我们确定在室温下单轴条件下转变 MoTe2 所需的拉伸应变范围为 0.3% 至 3%。预测了所有六种研究化合物的机械相变潜力。
Mo- and W-dichalcogenide compounds have a two-dimensional monolayer form that differs from graphene in an important respect: it can potentially have more than one crystal structure. Some of these monolayers exhibit tantalizing hints of a poorly understood structural metal-to-insulator transition with the possibility of long metastable lifetimes. If controllable, such a transition could bring an exciting new application space to monolayer materials beyond graphene. Here we discover that mechanical deformations provide a route to switching thermodynamic stability between a semiconducting and a metallic crystal structure in these monolayer materials. Based on state-of-the-art density functional and hybrid Hartree-Fock/density functional calculations including vibrational energy corrections, we discover that MoTe2 is an excellent candidate phase change material. We identify a range from 0.3 to 3% for the tensile strains required to transform MoTe2 under uniaxial conditions at room temperature. The potential for mechanical phase transitions is predicted for all six studied compounds.