Dresden 2026 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 37: Ultrafast electron dynamics at surface and interfaces – Poster (joint session O/TT)

TT 37.11: Poster

Tuesday, March 10, 2026, 14:00–16:00, P2

Ultrafast electron dynamics in the valence-fluctuating intermetallic EuIr₂Si₂ — •Abeer Arora¹, Túlio de Castro¹, Amine Wahada¹, Lawson Lloyd¹, Tommaso Pincelli², Kristin Kliemt³, Cornelius Krellner³, Denis V. Vyalikh^4,5, Yoav Will Windsor², Martin Wolf¹, Ralph Ernstorfer^1,2, and Laurenz Rettig¹ — ¹Fritz Haber Institute of the Max Planck Society, Berlin, Germany — ²Institut für Physik und Astronomie, TU Berlin, Germany — ³Physikalisches Institut, Göthe-Universität Frankfurt, Germany — ⁴Donostia International Physics Center, San Sebastián, Spain — ⁵Ikerbasque, Basque Foundation for Science, Bilbao, Spain

EuIr₂Si₂ is a valence-fluctuating intermetallic compound that, despite its non-magnetic bulk, develops 2D ferromagnetic order below 48 K in the topmost Eu layer due to a stable Eu²⁺ configuration. Its heavy Ir ions generate strong Rashba spin-orbit coupling, which interacts with magnetic exchange and influences the surface electronic states. Probing the non-equilibrium dynamics of the 2D electrons in the Si-Ir-Si surface layer offers a direct way to study the coupling of the spin-orbit and surface magnetic interaction. Using femtosecond XUV time- and angle-resolved photoemission spectroscopy, we investigate how the surface states evolve following photoexcitation with a 1.55 eV pulsed laser. Our preliminary results show an ultrafast quenching of the surface-state splitting, which we discuss in terms of demagnetization of the Eu 4f moments and modified spin-orbit coupling.

Keywords: Intermetallics; Mixed-valent; Ultrafast 2D magnetism; Rashba spin-orbit coupling; trAPRES