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arXiv · 2012.01645

Temperature evolution of quasiparticle dispersion dynamics in semimetallic 1T-TiTe2 via high-resolution angle-resolved photoemission spectroscopy and ultrafast optical pump-probe spectroscopy

Shuang-Xing Zhu·Chen Zhang·Qi-Yi Wu·Xiao-Fang Tang·Hao Liu·Zi-Teng Liu·Yang Luo·Jiao-Jiao Song·Fan-Ying Wu·Yin-Zou Zhao·Shu-Yu Liu·Tian Le·Xin Lu·He Ma·Kai-Hui Liu·Ya-Hua Yuan·Han Huang·Jun He·H. Y. Liu·Yu-Xia Duan·Jian-Qiao Meng
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Abstract

High-resolution angle-resolved photoemission spectroscopy and ultrafast optical pump-probe spectroscopy were used to study semimetallic 1T - TiTe2 quasiparticle dispersion and dynamics. A kink and a flat band, having the same energy scale and temperature-dependent behaviors along the G-M direction, were detected. Both manifested at low temperatures but blurred as temperature increased. The kink was formed by an electron-phonon coupling. And the localized flat band might be closely related to an electron-phonon coupling. Ultrafast optical spectroscopy identified multiple distinct time scales in the 10-300 K range. Quantitative analysis of the fastest decay process evidenced a significant lifetime temperature dependence at high temperatures, while this starts to change slowly below ~ 100 K where an anomalous Hall coefficient occurred. At low temperature, a coherent A1g phonon mode with a frequency of ~ 4.36 THz was extracted. Frequency temperature dependence suggests that phonon hardening occurs as temperature falls and anharmonic effects can explain it. Frequency fluence dependence indicates that the phonons soften as fluence increases.

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Shuang-Xing Zhu, Chen Zhang, Qi-Yi Wu, Xiao-Fang Tang, Hao Liu, Zi-Teng Liu, Yang Luo, Jiao-Jiao Song, Fan-Ying Wu, Yin-Zou Zhao, Shu-Yu Liu, Tian Le, Xin Lu, He Ma, Kai-Hui Liu, Ya-Hua Yuan, Han Huang, Jun He, H. Y. Liu, Yu-Xia Duan, Jian-Qiao Meng. 2020-12-03. Temperature evolution of quasiparticle dispersion dynamics in semimetallic 1T-TiTe2 via high-resolution angle-resolved photoemission spectroscopy and ultrafast optical pump-probe spectroscopy. https://doi.org/10.1103/physrevb.103.115108

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