Changes of the electronic structure of FeTe_1−xSe_x (x = 0, 0.3) upon ultrafast excitation with near-infrared laser pulses are investigated using time- and angle-resolved extreme ultraviolet photoemission spectroscopy. At different temperatures and for different doping levels we observe a global oscillation of energy bands near the Fermi energy driven by the coherent excitation of the A_1g(Te) phonon mode in FeTe_1−xSe_x. Prominently, photo-induced band shifts and a spectral weight reduction persist for at least 300 ps, long after the decay of the photo-excited carriers and the damping of the coherent phonons. We argue that the system escapes from the original equilibrium state and is transiently trapped in a possibly metastable state envisioning a purely optical means of manipulating the electronic structure in an iron-based superconductor.

使用时间和角度分辨的极紫外光发射光谱研究了在用近红外激光脉冲进行超快激发后 FeTe _{1− x} Se _x (x = 0, 0.3)电子结构的变化。在不同的温度和不同的掺杂水平下，我们观察到FeTe _{1- x} Se _x处的A _{1 g}（Te）声子模的相干激发所驱动的费米能量附近的能带整体振荡. 值得注意的是，在光激发载流子衰减和相干声子衰减很久之后，光致带移和光谱重量减少持续至少 300 ps。我们认为，该系统脱离了原始的平衡状态，并被暂时困在可能处于亚稳态的状态，从而设想了一种纯粹的光学手段来操纵铁基超导体中的电子结构。