In this work, we provide an effective model to evaluate the one-electron dipole matrix elements governing optical excitations and the photoemission process of single-layer (SL) and bilayer (BL) transition metal dichalcogenides. By utilizing a k⋅p Hamiltonian, we calculate the photoemission intensity as observed in angle-resolved photoemission from the valence bands around the Kˉ-valley of MoS2. In SL MoS2 we find a significant masking of intensity outside the first Brillouin zone, which originates from an in-plane interference effect between photoelectrons emitted from the Mo d orbitals. In BL MoS2 an additional inter-layer interference effect leads to a distinctive modulation of intensity with photon energy. Finally, we use the semiconductor Bloch equations to model the optical excitation in a time- and angle-resolved pump-probe photoemission experiment. We find that the momentum dependence of an optically excited population in the conduction band leads to an observable dichroism in both SL and BL MoS2.
@article{arxiv.1910.01882,
title = {Layer and orbital interference effects in photoemission from transition metal dichalcogenides},
author = {Habib Rostami and Klara Volckaert and Nicola Lanata and Sanjoy K. Mahatha and Charlotte E. Sanders and Marco Bianchi and Daniel Lizzit and Luca Bignardi and Silvano Lizzit and Jill A. Miwa and Alexander V. Balatsky and Philip Hofmann and Søren Ulstrup},
journal= {arXiv preprint arXiv:1910.01882},
year = {2019}
}