Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 32: Electronic structure of surfaces: Spectroscopy, surface states I

O 32.2: Vortrag

Dienstag, 13. März 2018, 14:15–14:30, MA 004

Photoelectron Momentum Microscopy with Large k-Field of View using Soft X-Rays — •Sergey Babenkov¹, Arndt Quer², Katerina Medjanik¹, Dmitry Vasilyev¹, Martin Ellguth¹, Florian Diekmann², Sebastian Rolf², Matthias Kalläne², Kai Rossnagel², Jens Viefhaus³, Hans-Joachim Elmers¹, and Gerd Schönhense¹ — ¹JGU, Inst. für Physik, Mainz — ²CAU, Inst. für Exp. und Angew. Physik, Kiel — ³DESY, Hamburg, Germany

Time-of-flight k-microscopy at the high-brilliance soft X-ray beamline P04 (PETRA III) was employed for studying the electronic structure of several transition-metal dichalcogenides. Main emphasis was to maximize the field-of-view in k-space allowing to observe the k-patterns and circular dichroism (CDAD) texture in several repeated Brillouin zones (BZs) along k_x,y (parallel) and k_z (perpendicular to the surface). CDAD patterns exhibit a rich texture, varying with k-vector in all directions and with photon energy. The dichalcogenides constitute an interesting intermediate case between true 2D systems as discussed in early CDAD work [1] and bulk systems as studied recently [2]. Varying k_z in small steps via the photon energy (from 290 to 370 eV, with ca. 5 eV increment) reveals strong redistributions of spectral weight of the Fermi-surface pockets at Γ, M, M’ between the first and the repeated BZs along k_x,y. This is accompanied by pronounced changes in the CDAD texture. The variation with k_z allows to quantify the size of the quasi-3D Fermi surface via tomographic k-space mapping.

[1] G. Schönhense, Phys. Scripta T31, 255 (1990); [2] O. Fedchenko et al., submitted (2017)