Femtosecond dynamics in layered materials

这个项目的目标是研究层状材料中的超快电子动力学，范围从具有原子厚度的二维系统到拓扑绝缘体和非传统超导体，其中维度和二维电子气的微观物理起着关键作用。这一研究课题将需要在超快光谱技术方面取得重大进展，并开发一种新的装置来研究脉冲光激励驱动的飞秒动力学。人们对层状材料的物理特别感兴趣，因为它们的特殊特性可以在光电子学和电子学的单原子厚度器件中得到技术上的利用，从而克服当前半导体技术的小型化限制。要全面研究发生在这种维度尺度上的基本过程，如电子-电子和电子-声子散射机制，就需要实施一种能够实现极高时间分辨率、结合广泛光谱覆盖和特殊灵敏度的超快光谱系统。特别是，我们将专注于产生各种光谱范围的超短光脉冲，用于双色泵浦-探测实验，目标是获得低于10-fs的时间分辨率。高重复率将确保对少数/单层材料产生的小信号进行灵敏检测。利用在该项目中开发的新的光谱工具，将有可能揭示最终的电荷动力学，这些动力学是二维系统光学和电子性质的基础。

This project aims at the study of ultrafast electronic dynamics in the class of layered materials, ranging from two-dimensional systems with atomic thickness to topological insulators and nonconventional superconductors where dimensionality and the microscopic physics of two-dimensional electron gases play a key role. This research topic will require significant advances in ultrafast spectroscopy techniques and the development of a new setup for the study of femtosecond dynamics driven by impulsive photoexcitation. The particular interest in the physics of layered materials is related to their peculiar characteristics that can be technologically exploited in mono-atomically thick devices for optoelectronics and electronics, thus overcoming the miniaturization limitations of current semiconductor technologies.A full study of the fundamental processes, such as electron-electron and electron-phonon scattering mechanisms occurring at this dimensional scale, calls for the implementation of an ultrafast spectroscopy system capable of extreme temporal resolution combined to broad spectral coverage and exceptional sensitivity. In particular, we will focus on the generation of ultrashort optical pulses in various spectral ranges to be employed in two-color pump-probe experiments with the goal to obtain sub-10-fs temporal resolution. High repetition rate will ensure sensitive detection of the small signal arising from few/mono-layered materials. With the novel spectroscopic tools developed in the project, it will be possible to unveil the ultimate charge dynamics that are at the basis for the optical and electronic properties in 2-dimensional systems.