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arXiv 2207.05232cond-mat.str-elcond-mat.mtrl-sci
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Mott绝缘电荷密度波态下光激发1T-TaS2光电子能谱的相位分辨频域分析

Phase-resolved frequency-domain analysis of the photoemission spectra for photoexcited 1T-TaS2 in the Mott insulating charge density wave state

Q. -H. Ren, T. Suzuki, T. Kanai, J. Itatani, S. Shin, K. Okazaki

AI总结:

本研究利用时间分辨角分辨光电子能谱及FDARPES分析光激发1T-TaS2,揭示CDW振幅模通过晶格调制动态改变Mott能隙,而CDW平带依然保持。

摘要:

我们利用时间分辨和角分辨光电子能谱研究了1T-TaS2的非平衡电子结构。我们观察到,强光激发会引起Mott能隙坍塌,从而形成光致金属相。研究还发现,由于对应于电荷密度波(CDW)振幅模的相干声子被激发,光电子发射强度出现振荡。为了研究由CDW振幅模调制的能带色散的动态变化,我们采用频域角分辨光电子能谱(FDARPES)进行分析。通过提取FDARPES谱的振幅和相位部分,我们发现两种不同的峰结构彼此呈现反相振荡。它们归因于能量上的最低和最高能带位置,单一能带在这两个位置之间随CDW振幅模同步振荡。我们进一步发现,尽管Mott能隙显著减小,但由CDW能带折叠形成的平带在振荡过程中仍然存在。我们的结果表明,CDW相是稳健的,并且与CDW振幅模相对应的晶格调制会动态调制Mott能隙。

英文摘要:

We investigate the nonequilibrium electronic structure of 1T-TaS2 by time- and angle-resolved photoemission spectroscopy. We observe that strong photoexcitation induces the collapse of the Mott gap, leading to the photo-induced metallic phase. It is also found that the oscillation of photoemission intensity occurs as a result of the excitations of coherent phonons corresponding to the amplitude mode of the charge density wave (CDW). To study the dynamical change of the band dispersions modulated by the CDW amplitude mode, we perform analyses by using frequency-domain angle-resolved photoemission spectroscopy (FDARPES). We find that two different peak structures exhibit anti-phase oscillation with respect to each other by retrieving the amplitude and phase parts of the FDARPES spectra. They are attributed to the minimum and maximum band positions in energy, where the single band is oscillating between them synchronizing with the CDW amplitude mode. We further find that the flat band constructed as a result of CDW band folding survives during the oscillation while the Mott gap is significantly reduced. Our results suggest the CDW phase is robust, and the lattice modulation corresponding to the CDW amplitude mode dynamically modulates the Mott gap.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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