Real space Green's function approach to angle resolved resonant photoemission: spin polarization and circular dichroism in itinerant magnets

TL;DR

This paper introduces a first-principles real space Green's function method to analyze spin-resolved resonant photoemission in magnetic materials, revealing how resonance conditions affect spectra, spin polarization, and dichroism.

Contribution

It presents a novel computational approach combining multiple scattering Green's functions with first-principles calculations for spin-resolved photoemission.

Findings

Resonance significantly alters spectral intensities and spin polarization.

Identification of spin-flip transitions induced by exchange decay.

Influence of intra-atomic and multiple scattering effects on spectra.

Abstract

A first principles approach, based on the real space multiple scattering Green's function method, is presented for spin- and angle-resolved resonant photoemission from magnetic surfaces. It is applied to the Fe(010) valence band photoemission excited with circularly polarized X-rays around the Fe L3 absorption edge. When the photon energy is swept through the Fe 2p-3d resonance, the valence band spectra are strongly modified in terms of absolute and relative peak intensities, degree of spin-polarization and light polarization dependence. New peaks in the spin-polarized spectra are identified as spin-flip transitions induced by exchange decay of spin-mixed core-holes. By comparison with single atom and band structure data, it is shown that both intra-atomic and multiple scattering effects strongly influence the spectra. We show how the different features linked to states of different orbital symmetry in the d band are differently enhanced by the resonant effect. The appearance and origin of circular dichroism and spin polarization are analyzed for different geometries of light incidence and electron emission direction, providing guidelines for future experiments.