论文标题
在光诱导的相变期间检测电子偶联
Detecting electron-phonon couplings during photo-induced phase transition
论文作者
论文摘要
由于能够以超快方式控制感兴趣的材料，因此对光诱导的相变已进行了深入研究，这可以诱导无法在平衡处获得无法实现的外来相位。但是，关键机制仍在争论中，目前一直是电子，晶格和自由度自由度之间的耦合如何在光诱导的相转换过程中发展的核心问题。在这里，我们开发了一种新的分析方法，即频域角度分辨光发射光谱，以在光诱导的绝缘体到金属转换期间，可以准确洞悉电子 - phonon耦合。我们证明，由位移激发产生的多个相干声子表明带与电子的耦合。此外，我们发现与2个THZ声子模式相对应的晶格调制，其中TA晶格沿A轴剪切，是与光诱导的半金属态最相关的。
Photo-induced phase transitions have been intensively studied owing to the ability to control a material of interest in the ultrafast manner, which can induce exotic phases unable to be attained at equilibrium. However, the key mechanisms are still under debate, and it has currently been a central issue how the couplings between the electron, lattice, and spin degrees of freedom are evolving during photo-induced phase transitions. Here, we develop a new analysis method, frequency-domain angle-resolved photoemission spectroscopy, to gain precise insight into electron-phonon couplings during photo-induced insulator-to-metal transitions for Ta$_2$NiSe$_5$. We demonstrate that multiple coherent phonons generated by displacive excitations show band-selective coupling to the electrons. Furthermore, we find that the lattice modulation corresponding to the 2 THz phonon mode, where Ta lattice is sheared along the a-axis, is the most relevant for the photo-induced semimetallic state.
