Strongly Coupled Electron–Phonon Dynamics in Few-Layer TiSe2 Exfoliates,ACS Photonics

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Strongly Coupled Electron–Phonon Dynamics in Few-Layer TiSe2 Exfoliates
ACS Photonics ( IF 6.5 ) Pub Date : 2018-02-07 00:00:00 , DOI: 10.1021/acsphotonics.7b00878
Tony E. Karam ₁ , Jianbo Hu _{1,

2} , Geoffrey A. Blake _{1,

3}

Affiliation

Ultrafast electron diffraction is used to probe the time-resolved dynamics in a few-layer TiSe₂ sample. At normal incidence, the suppression of the Bragg diffraction peak intensities following photoexcitation displays strongly biexponential behavior. For tilted samples, changes in the diffraction peak positions reveal coherent acoustic vibrations that are dependent on the sample thickness and that further permit a calculation of the Young’s modulus. The complex room temperature lattice dynamics observed are attributed to strong electron–phonon coupling and electron–lattice equilibration processes, which support a Jahn–Teller origin of the charge density wave behavior in TiSe₂. Additionally, the significant role that the related Kohn anomalies may play in the electron transport dynamics and transition mechanism of this material is emphasized. These results demonstrate the importance of strongly coupled electron–phonon dynamics in the relaxation of electronically excited room temperature TiSe₂, which is expected to impact its applicability in optoelectronics.

中文翻译：

几层TiSe ₂剥落物中的强耦合电子-声子动力学

超快电子衍射用于探测几层TiSe ₂样品中的时间分辨动力学。在垂直入射下，光激发后对布拉格衍射峰强度的抑制表现出很强的双指数行为。对于倾斜的样品，衍射峰位置的变化会显示出相干的声振动，该振动取决于样品的厚度，并进一步允许计算杨氏模量。观察到的复杂的室温晶格动力学归因于强的电子-声子耦合和电子-晶格平衡过程，这支持了TiSe _2中电荷密度波行为的Jahn-Teller起源。。此外，还强调了相关的Kohn异常可能在这种材料的电子传输动力学和跃迁机制中发挥的重要作用。这些结果证明了强耦合电子-声子动力学在电子激发的室温TiSe ₂弛豫中的重要性，这有望影响其在光电学中的适用性。

更新日期：2018-02-07

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