Ab initio simulation of attosecond transient absorption spectroscopy in two-dimensional materials

TL;DR

This paper extends ab initio methods to analyze attosecond transient absorption in two-dimensional materials, specifically monolayer h-BN, revealing nonadiabatic effects and the role of intraband transitions and the dynamical Franz-Keldysh effect.

Contribution

It introduces a first-principles approach to study attosecond spectroscopy in 2D materials, highlighting the significance of intraband transitions and nonadiabatic effects.

Findings

Nonadiabatic features observed in transient absorption spectra.

Laser-induced intraband transitions significantly influence the spectra.

Dynamical Franz-Keldysh effect causes nonadiabatic features in 2D materials.

Abstract

We extend the first-principles analysis of attosecond transient absorption spectroscopy to two-dimensional materials. As an example of two-dimensional materials, we apply the analysis to monolayer hexagonal boron nitride (h-BN) and compute its transient optical properties under intense few-cycle infrared laser pulses. Nonadiabatic features are observed in the computed transient absorption spectra. To elucidate the microscopic origin of these features, we analyze the electronic structure of h-BN with density functional theory and investigate the dynamics of specific energy bands with a simple two-band model. Finally, we find that laser-induced intraband transitions play a significant role in the transient absorption even for the two-dimensional material and that the nonadiabatic features are induced by the dynamical Franz-Keldysh effect with an anomalous band dispersion.