论文标题
电荷密度波转换1T-Tite $ _2 $的厚度依赖性理论
Theory of the thickness dependence of the charge density wave transition in 1T-TiTe$_2$
论文作者
论文摘要
大多数金属过渡金属二进制基因源都会在散装和单层中具有相似或相同的排序向量，但具有电荷密度波（CDW）的不稳定性，尽管具有不同的临界温度。金属1T-Tite $ _2 $是一个了不起的例外，因为它没有显示批量形成电荷密度波的证据，但它以单层形式显示稳定的$ 2 \ times2 $重建。尽管底物和交换相互作用的应变已被指出为可能的形成机制，但这种转变的3D-2D交叉的机制仍不清楚。在这里，通过使用梯度校正和混合功能执行非扰动的非锤子计算，我们可以解释1T-Tite $ _2 $中过渡的厚度行为。我们证明，CDW在单层tite $ _2 $中的出现来自非扰动非harm谐性的相互作用和电子 - 音波相互作用的交换增强，而单层比体积大。最后，我们研究了单层CDW相的电子和结构特性，并提供了其电子结构，声子分散以及红外和拉曼活性声子模式的完整描述。
Most metallic transition metal dichalcogenides undergo charge density wave (CDW) instabilities with similar or identical ordering vectors in bulk and in single layer, albeit with different critical temperatures. Metallic 1T-TiTe$_2$ is a remarkable exception as it shows no evidence of charge density wave formation in bulk, but it displays a stable $2\times2$ reconstruction in single-layer form. The mechanism for this 3D-2D crossover of the transition is still unclear, although strain from the substrate and the exchange interaction have been pointed out as possible formation mechanisms. Here, by performing non-perturbative anharmonic calculations with gradient corrected and hybrid functionals, we explain the thickness behaviour of the transition in 1T-TiTe$_2$. We demonstrate that the occurrence of the CDW in single-layer TiTe$_2$ occurs from the interplay of non-perturbative anharmonicity and an exchange enhancement of the electron-phonon interaction, larger in the single layer than in the bulk. Finally, we study the electronic and structural properties of the single-layer CDW phase and provide a complete description of its electronic structure, phonon dispersion as well as infrared and Raman active phonon modes.
