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MA: Fachverband Magnetismus
MA 17: Computational Magnetism II
MA 17.10: Vortrag
Dienstag, 19. März 2024, 12:00–12:15, EB 202
Ab-initio study of x-ray circular dichroism in chiral solids: disentangling magnetic and natural cross-sections — •Alberto Marmodoro1,2, Ondrej Sipr1,2, Sergiy Mankovsky3, and Hubert Ebert3 — 1Institute of Physics (FZU), AS CR Prague, Czech Republic — 2New Technologies Center (NTC), University of West Bohemia, Plzen, Czech Republic — 3Ludwig Maximilians University (LMU), Munich, Germany
Circular dichroism in x-ray absorption (XCD), i.e. the different cross-section for a left or right circularly polarized beam, can arise from a variety of mechanisms.
Ferromagnetic order leads to a magnetic signal (XMCD) which mainly arises from dipole-allowed transitions and which follows a well-known cosine dependence with respect to azimuthal angle between beam and magnetic moments.
Even in the absence of atomic magnetic moment, a chiral arrangement of the atoms lead among other chirality induced spin-selectivity effects (CISS) to a "natural" signal (XNCD) [1-2], which involves instead higher order terms in electron-photon interaction and which also follows a different angular dependence.
We use fully-relativistic multiple scattering / Green's function methods (KKR-GF) and density functional theory (DFT) plus enhancements for core-hole effects, in order to numerically study this phenomenology in e.g. Strukturbericht B20 compounds, and to offer some predictions for the different impact of finite temperature effects [3] onto the two above components of XCD.
Keywords: chirality induced spin selectivity (CISS); x-ray absorption (XAS/XMCD); multiple scattering (KKR); theoretical spectroscopy; finite temperature