论文标题
vse $ _2 $的3D电荷密度波的声子崩溃和范德华熔化的熔化
Phonon collapse and van der Waals melting of the 3D charge density wave of VSe$_2$
论文作者
论文摘要
在过渡金属二分法（TMD）中，VSE $ _2 $被认为是在T $ _ {cdw} $ = 110 K处开发纯粹的3维（3D）电荷密度波（CDW）。在此，通过高分辨率的弹性X射线散射（IXS），我们显示了CDW次数的高度分辨率，我们表明CDW的过渡是驱动的。 \ textit {q} $ _ {cdw} $ =（2.25 0 0.7）r.l.u.和临界温度t $ _ {cdw} $ = 110 k。对于低于2 $ \ times $ t $ _ {cdw} $的温度开始，该模式的软化开始发音，并在布里远区域的一个相当广泛的区域扩展，这表明电子与CDW形成的电子相互作用很大。这种解释得到了我们的第一个原理计算的支持，这些计算决定了在存在嵌套的情况下，确定电子 - 光子相互作用的大量动量依赖性，在CDW波形处达到峰值。完全anharmonic {\ it In hibio}计算确认\ textit {q} $ _ {cdw} $的一个声学分支的软化为CDW组的负责，并表明van der waals的交互对于融化CDW至关重要。我们的工作还强调了平面外相互作用在描述TMD中的3D CDW的重要作用。
Among transition metal dichalcogenides (TMDs), VSe$_2$ is considered to develop a purely 3-dimensional (3D) charge-density wave (CDW) at T$_{CDW}$=110 K. Here, by means of high resolution inelastic x-ray scattering (IXS), we show that the CDW transition is driven by the collapse of an acoustic mode at the critical wavevector \textit{q}$_{CDW}$= (2.25 0 0.7) r.l.u. and critical temperature T$_{CDW}$=110 K. The softening of this mode starts to be pronounced for temperatures below 2$\times$ T$_{CDW}$ and expands over a rather wide region of the Brillouin zone, suggesting a large contribution of the electron-phonon interaction to the CDW formation. This interpretation is supported by our first principles calculations that determine a large momentum-dependence of the electron-phonon interaction, peaking at the CDW wavevector, in the presence of nesting. Fully anharmonic {\it ab initio} calculations confirm the softening of one acoustic branch at \textit{q}$_{CDW}$ as responsible for the CDW formation and show that van der Waals interactions are crucial to melt the CDW. Our work also highlights the important role of out-of-plane interactions to describe 3D CDWs in TMDs.
