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 kp Hamiltonian, we calculate the photoemission intensity as observed in angle-resolved photoemission from the valence bands around the K 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 interlayer 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.

Layer and orbital interference effects in photoemission from transition metal dichalcogenides

Bignardi, Luca
Membro del Collaboration Group
;
Hofmann, Philip
Membro del Collaboration Group
;
2019

Abstract

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 kp Hamiltonian, we calculate the photoemission intensity as observed in angle-resolved photoemission from the valence bands around the K 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 interlayer 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.
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https://journals.aps.org/prb/abstract/10.1103/PhysRevB.100.235423
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/2954239
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