Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 26: Focus Session Ultrafast Electron Microscopy at the Space-Time Limit III

O 26.6: Vortrag

Dienstag, 18. März 2025, 12:00–12:15, H2

FEL-based core-cum-conduction momentum microscopy of ultrafast charge-density-wave dynamics — •N. Wind^1,2,3, M. Heber^1,3, D. Kutnyakhov¹, L. Wenthaus¹, J. Dilling², L. Bruckmeier², S. Chernov¹, O. Tkach⁴, A. Mehta⁵, J. Koralek⁵, G. Dakovski⁵, J.A. Sobota⁶, P.E. Majchrzak⁶, D. Puntel⁶, D. Liu⁶, G. Schönhense⁴, H.J. Elmers⁴, Z.X. Shen⁶, M. Scholz¹, and K. Rossnagel^1,2 — ¹Deutsches Elektronen Synchrotron DESY, 22607 Hamburg, Germany — ²Christian-Albrechts-Universität zu Kiel IEAP, 24098 Kiel, Germany — ³Universität Hamburg, IExP, 22761 Hamburg, Germany — ⁴Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany — ⁵SLAC National Accelerator Laboratory, Menlo Park, CA 94205, USA — ⁶Stanford University, Institute for Materials and Energy Science, CA 94305, USA

Transition-metal dichalcogenides (TMDCs) offer a rich platform for studying novel forms of quantum and nanoelectronics in layered structures approaching the 2D limit. Among them, 1-T TaS₂ has been extensively studied due to its various charge-density-wave (CDW) phases. Here, we provide novel insights into the CDW melting in 1-T TaS₂, using time- and angle-resolved photoemission spectroscopy with a momentum microscope at the free-electron laser FLASH in Hamburg. Our near-infrared pump–FEL probe experiment uncovers momentum-dependent conduction-band dynamics and core-level responses, advancing our understanding of ultrafast coupled electronic and structural dynamics.

Keywords: Momentum Microscopy; FEL; Ultrafast; ARPES; TMDC