论文标题
在光激发之后揭示1T-TISE $ _2 $的顺序参数动力学
Revealing the order parameter dynamics of 1T-TiSe$_2$ following optical excitation
论文作者
论文摘要
电荷密度波状态的形成为特征在于顺序参数。建立的方式提供了有关相关性在推动电荷密度波的形成以及其形成背后的机制中起作用的作用的独特信息。在这里，我们使用时间和角度分辨率的光电子光谱法将电荷密度相动为1T-TISE $ _2 $，并遵循其顺序参数的恢复，这是能量，动量和激发密度的函数。我们的结果表明，两个不同的顺序有助于间隙形成，CDW顺序和类似伪PSE的顺序，这表现为光学激发的整体鲁棒性。详细分析了间隙的大小作为激发密度和延迟时间的函数，揭示了CDW间隙的激子长距离性质和伪PSEUDOGAP阶的短距离Jahn-Teller特征。与差距相反，折叠的SE $ _ {4p} $*频段的强度只能访问激子订单。这些结果为关于差距的起源的长期辩论提供了新的信息，并将其放置在其他量子材料的相同情况下，其中伪随阶段似乎是远程顺序的前体。
The formation of a charge density wave state is characterized by an order parameter. The way it is established provides unique information on both the role that correlation plays in driving the charge density wave formation and the mechanism behind its formation. Here we use time and angle resolved photoelectron spectroscopy to optically perturb the charge-density phase in 1T-TiSe$_2$ and follow the recovery of its order parameter as a function of energy, momentum and excitation density. Our results reveal that two distinct orders contribute to the gap formation, a CDW order and pseudogap-like order, manifested by an overall robustness to optical excitation. A detailed analysis of the magnitude of the the gap as a function of excitation density and delay time reveals the excitonic long-range nature of the CDW gap and the short-range Jahn-Teller character of the pseudogap order. In contrast to the gap, the intensity of the folded Se$_{4p}$* band can only give access to the excitonic order. These results provide new information into the the long standing debate on the origin of the gap in TiSe$_2$ and place it in the same context of other quantum materials where a pseudogap phase appears to be a precursor of long-range order.
