Revealing transient electronic properties in anisotropic 2D materials is a prerequisite for developing ultrafast optoelectronic functional devices. Here, the ultrafast electronic dynamics of polarization anisotropy for the AB-stacked rhenium disulfide (ReS₂) are studied using time- and energy-resolved photoemission electron microscopy. The ultrafast electronic relaxation process exhibits sensitive layer-dependent polarization anisotropy. The linear dichroism of the ultrafast electronic dynamics is also measured, indicating that the polarization anisotropy is determined by the fast process on the sub-picosecond scale. With ab initio theory calculations, it is confirmed that the ultra-sensitive layer dependence of the lifetime of the fast process originates from a stronger interlayer coupling in the K-Γ direction (along the b-axis) of ReS₂. Further, by analyzing the time-resolved photoemission energy spectrum, distinct “fast” and “slow” regimes are found in the ultrafast dynamics of excited electrons with different energies. The corresponding energy windows also show substantial polarization anisotropy, which is associated with the linear dichroism of the electron-phonon coupling in the AB-stacked ReS₂. This work has implications for the design of angle-sensitive optoelectronic functional devices with the AB-stacked ReS₂.

中文翻译：

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AB 堆叠二硫化铼中超快电子动力学的偏振各向异性


揭示各向异性二维材料的瞬态电子特性是开发超快光电功能器件的先决条件。在这里，使用时间和能量分辨光电子显微镜研究了 AB 堆叠的二硫化铼 (ReS ₂ ) 的偏振各向异性的超快电子动力学。超快电子弛豫过程表现出敏感的层相关偏振各向异性。还测量了超快电子动力学的线性二向色性，表明偏振各向异性是由亚皮秒尺度的快速过程决定的。通过从头理论计算，证实了快速过程寿命的超敏感层依赖性源于ReS ₂ 中电子-声子耦合的线性二向色性有关。这项工作对于采用AB堆叠ReS ₂ 的角度敏感光电功能器件的设计具有重要意义。