Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 22: 2D Materials II: Electronic Structure (joint session O/TT)
O 22.1: Talk
Tuesday, March 19, 2024, 10:30–10:45, MA 005
On the origin of circular dichroism from graphene, WSe2, and other quantum materials — •Lukasz Plucinski — PGI-6 Forschungszentrum Jülich
On the example of graphene, within the dipole approximation, we discuss various contributions to the circular-dichroic angle-resolved photoemission (CD-ARPES) [1] which include phase shifts of the participating partial waves in the atomic photoionization [2], the finite inelastic mean free path induced CD [3], the interatomic phase shifts [4], and the CD due to multiple scattering of the excited electron [5]. Using tabulated phase shifts and radial integrals [6], we predict photon energies at which CD signal might exhibit sign changes, and compare the prediction to experimental results. Subsequently, we perform similar analysis for WSe2, a material where orbital characters are relatively well-defined, however, varying over Brillouin zone, with different contributions at K, K’, and Γ points. This can be translated into understanding CD-ARPES from topological materials. Within this context, we briefly discuss how various components needed to derive the Berry curvature, the spin characters [4], and the phases of the wave functions, can be accessed through CD-ARPES and its spin-polarized variant.
[1] Plucinski, arXiv:2309.02187 (2023), [2] Dubs et al., Phys. Rev. B 32, 8389 (1985) [3] Moser, JESRP 214, 29 (2017) [4] Heider, et al., PRL 130, 146401 (2023) [5] Daimon et al., JJAP 32, L1480 (1993) [6] Goldberg et al., JESRP 21, 285 (1981)
Keywords: photoemission; circular dichroism; Berry curvature; angle-resolved photoemission; electron scattering