论文标题
前体阶段，具有全声子软化，高于电荷密度 - 波相变的$ 2H $ tase $ _2 $
Precursor phase with full phonon softening above the charge-density-wave phase transition in $2H$-TaSe$_2$
论文作者
论文摘要
对电荷密度波（CDW）有序的过渡金属二核苷的研究继续揭示与缠绕的晶格和电子自由度相关的量子物质的新状态。在这里，我们报告了针对角度分辨光发射光谱辅助的规范CDW化合物$ 2H $ tase $ _2 $的晶格动力学的非弹性X射线散射研究。我们的结果排除了CDW过渡以$ 2H $ -TASE $ _2 $的中心峰值场景，并为CDW过渡温度$ T_ {CDW} $上方的新型前体阶段提供了证据。 $ t^{*} \，（= 128.7 \ ,, \ rm {k}）$和$ t_ {cdw} \，（= 121.3 \，\ rm {k}）$之间的温度相位的阶段。 100 \，\ rm {\ Mathring {a}} -200 \，\ rm {\ Mathring {a}}）$ static CDW域。在我们的光发射实验中只能检测到$ t_ {cdw} $。因此，$ 2H $ tase $ _2 $在电子静态订单之前显示结构性，并强调了对CDW过渡的重要晶格贡献。
Research on charge-density-wave (CDW) ordered transition-metal dichalcogenides continues to unravel new states of quantum matter correlated to the intertwined lattice and electronic degrees of freedom. Here, we report an inelastic x-ray scattering investigation of the lattice dynamics of the canonical CDW compound $2H$-TaSe$_2$ complemented by angle-resolved photoemission spectroscopy. Our results rule out the central-peak scenario for the CDW transition in $2H$-TaSe$_2$ and provide evidence for a novel precursor phase above the CDW transition temperature $T_{CDW}$. The phase at temperatures between $T^{*}\,(= 128.7\,,\rm{K})$ and $T_{CDW}\,(= 121.3\,\rm{K})$ is characterized by a fully softened phonon mode and medium-range ordered ($ξ_{corr} = 100\,\rm{\mathring{A}}- 200\,\rm{\mathring{A}})$ static CDW domains. Only $T_{CDW}$ is detectable in our photoemission experiments. Thus, $2H$-TaSe$_2$ exhibits structural before electronic static order and emphasizes the important lattice contribution to CDW transitions.
