1 T- TaSe2-xTex中的无序抑制电荷密度波及其起源
Disorder suppressed charge-density-wave and its origin in 1T-TaSe2-xTex
摘要：
为了将TaSe $_2$的电荷密度波（CDW）与TaTe $_2$的单\emph{\textbf{q}} CDW型畸变联系起来，我们给出了1 \emph{T} $_{2-x}$ Te $_x$（$0 \leq x \leq 2$）的电子相图.在实验制备的单晶中，CDW被完全抑制为$0.5 < x < 1.5$，而超导性以$0.2 < x < 1.2$出现。理论上，类似于1 \emph{T} -TaSe $_2$和1 \emph{T} -TaTe $_2$，具有有序Se/Ta/Te堆叠的假设1 \emph{T} -TaSeTe显示声子色散的不稳定性，表明在理想有序样品中存在CDW。实验和理论结果之间的矛盾表明，在1 \emph{T} -TaSe $_{2-x}$ Te $_x$中，CDW被无序抑制。CDW的形成和抑制被发现是独立的费米面嵌套的基础上产生的电子磁化率计算。声子线宽的计算表明，强的\textbf{\emph{q}}依赖的电子-声子耦合引起的周期晶格畸变（PLD）与我们的观察有关：掺杂可以极大地畸变TaX $_6$（X = Se，Te）八面体，它们是无序分布的。所得到的起皱的Ta-Ta层与二维PLD不兼容。因此，1 \emph{T} -TaSe $_{2-x}$ Te $_x$中的CDW被抑制。我们的结果提供了一个间接的证据，PLD，可以受到强无序的影响，是在系统中的CDW的起源。
英文摘要：
In the sake of connecting the charge-density-wave (CDW) of TaSe$_2$ and single-\emph{\textbf{q}} CDW-type distortion of TaTe$_2$, we present an overall electronic phase diagram of 1\emph{T}-TaSe$_{2-x}$Te$_x$ ($0 \leq x \leq 2$). In the experimentally prepared single crystals, the CDW is completely suppressed as $0.5 < x < 1.5$, while superconductivity emerges as $0.2 < x < 1.2$. Theoretically, similar to 1\emph{T}-TaSe$_2$ and 1\emph{T}-TaTe$_2$, the hypothetic 1\emph{T}-TaSeTe with ordered Se/Ta/Te stacking shows instability in the phonon dispersion, indicating the presence of CDW in the ideally ordered sample. The contradictory between experimental and theoretical results suggests that the CDW is suppressed by disorder in 1\emph{T}-TaSe$_{2-x}$Te$_x$. The formation and suppression of CDW are found to be independent with Fermi surface nesting based on the generated electron susceptibility calculations. The calculation of phonon linewidth suggests the strong \textbf{\emph{q}}-dependent electron-phonon coupling induced period-lattice-distortion (PLD) should be related to our observation: The doping can largely distort the TaX$_6$ (X = Se, Te) octahedra, which are disorderly distributed. The resulted puckered Ta-Ta layers are not compatible with the two-dimensional PLD. Therefore, CDW is suppressed in 1\emph{T}-TaSe$_{2-x}$Te$_x$. Our results offer an indirect evidence that PLD, which can be influenced by strong disorder, is the origin of CDW in the system.
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