论文标题
相干的声子以及1 $ t $ t $ t $ _ {2} $的电荷密度波和莫特阶段之间的相互作用
Coherent phonons and the interplay between charge density wave and Mott phases in 1$T$-TaSe$_{2}$
论文作者
论文摘要
1 $ t $ -tase $ _ {2} $是主机，可以共存强相关的相位，包括电荷密度波（CDW）和低温下的异常莫特过渡。在这里，我们使用时间和角度分辨的光发射光谱（TR-ARPES）和时间分辨反射率（TRR）的组合研究了1 $ t $ t $ _ {2} $中1 $ t $ t $ _ {2} $中相干的声子振荡。飞秒激光脉冲的扰动会触发与Mott GAP相关的$γ$点处的价带结合能的调制，这与平面CDW振幅模式频率一致。相比之下，TRR测量结果显示了由属于扭曲的CDW晶格模式的多个频率组成的差异反射率的调节。比较在CDW过渡中相干和自发声子的温度依赖性表明，与其他模式相比，光学激发在CDW状态的扰动过程中更容易抑制振幅模式强度。我们的结果清楚地确定了平面内CDW振幅模式与Mott阶段的关系1 $ t $ -tase $ _ {2} $，并突出了晶格自由度的重要性。
1$T$-TaSe$_{2}$ is host to coexisting strongly-correlated phases including charge density waves (CDWs) and an unusual Mott transition at low temperature. Here, we investigate coherent phonon oscillations in 1$T$-TaSe$_{2}$ using a combination of time- and angle-resolved photoemission spectroscopy (TR-ARPES) and time-resolved reflectivity (TRR). Perturbation by a femtosecond laser pulse triggers a modulation of the valence band binding energy at the $Γ$-point, related to the Mott gap, that is consistent with the in-plane CDW amplitude mode frequency. By contrast, TRR measurements show a modulation of the differential reflectivity comprised of multiple frequencies belonging to the distorted CDW lattice modes. Comparison of the temperature dependence of coherent and spontaneous phonons across the CDW transition shows that the amplitude mode intensity is more easily suppressed during perturbation of the CDW state by the optical excitation compared to other modes. Our results clearly identify the relationship of the in-plane CDW amplitude mode with the Mott phase in 1$T$-TaSe$_{2}$ and highlight the importance of lattice degrees of freedom.
