A toy model for dichroism in angle resolved photoemission

https://doi.org/10.1016/j.elspec.2022.147278Get rights and content
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Highlights

  • Angle-resolved photoemission is described in terms of the Huygens-Fresnel principle.

  • The plane wave approximation is augmented to describe energy dependent dichroism.

  • Amplitude and phase of the final state is extracted directly from ARPES intensity.

  • The wave function of p-orbital systems can be reconstructed from ARPES dichroism.

  • (Spin-) ARPES dichroism is analysed exemplarily for Rashba systems BiAg2 and AgTe.

Abstract

Angle-resolved photoemission spectroscopy (ARPES) measures the interference of dipole allowed Coulomb wavelets from the individual orbital emitters that contribute to an electronic band. If Coulomb scattering of the outgoing electron is neglected, this Huygens view of ARPES simplifies to a Fraunhofer diffraction experiment, and the relevant cross-sections to orbital Fourier transforms. This plane wave approximation (PWA) is surprisingly descriptive of photoelectron distributions, but fails to reproduce kinetic energy dependent final state effects like dichroism. Yet, Huygens principle of ARPES can be parsimoniously adapted to allow for distortion and phase shift of the outgoing Coulomb wave. This retains the strong physical intuition and low computational cost of the PWA, but naturally captures momentum dependent interference phenomena that so far required relativistic one-step modeling, such as linear dichroism in Rashba systems BiAg2 and AgTe.

Keywords

Huygens–Fresnel principle
ARPES intensity distribution
ARPES dichroism
Dipole matrix elements
Photon energy dependence
Independent center approximation
BiAg2
AgTe

Data availability

Data will be made available on request.

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