SKM 2023 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 26: Interface Controlled Properties and Nanomaterials: Grain Boundaries and Stability, Spectroscopy and Interatomic Potentials

MM 26.8: Vortrag

Mittwoch, 29. März 2023, 12:15–12:30, SCH A 216

Soft and Hard X-ray Circular Dichroism in Valence-Band and Core-Level Momentum Microscopy — •O. Tkach^1,2, O. Fedchenko¹, K. Medjanik¹, Y. Lytvynenko¹, S. Babenkov¹, D. Vasilyev¹, Q.L. Nguyen³, T.P. Vo⁴, T.R.F. Peixoto⁵, A. Gloskovskii⁵, C. Schlueter⁵, M. Hoesch⁵, D. Kutnyakhov⁵, M. Scholz⁵, L. Wenthaus⁵, N. Wind^5,6, S. Marotzke⁵, A. Winkelmann⁷, J. Minar⁴, K. Rossnagel^5,8, H.-J. Elmers¹, and G. Schönhense¹ — ¹Univ. Mainz — ²SSU, Ukraine — ³SLAC Nat. Accel. Lab., USA — ⁴Univ. West Bohemia, Czech — ⁵DESY Hamburg — ⁶Univ. Hamburg — ⁷AGH Univ., Poland — ⁸Univ. Kiel

We introduce full-field mapping of the circular dichroism texture in X-ray momentum microscopy. I(EB,k) energy-momentum space tomography with both soft and hard X-rays at PETRA-III yields CDAD patterns. Kinetic energies of up to >7 keV and a large k-field-of-view enable capturing of structural information via XPD Kikuchi patterns, which show pronounced asymmetries. Patterns at different azimuthal angles exhibit sharp zero lines, when the helicity vector lies in a mirror plane. Similar zero lines also appear in the XPD patterns of core levels, as exemplified for Ge 3p, Si 2p and various W core levels at hv = 6 keV. Calculations using Bloch-wave approach and one-step photoemission show good agreement with experiment. In order to disentangle the contributions of the photoexcitation (intrinsic part) from the Kikuchi process (extrinsic), XPD has been implemented in the Munich SPRKKR package, unifying one-step model of photoemission and multiple scattering theory.