Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 5: Ultrafast Electron Dynamics at Surfaces and Interfaces I
O 5.2: Vortrag
Montag, 18. März 2024, 10:45–11:00, MA 041
The wandering spins of Fe3GeTe2: itinerant vs localized behaviour in the electronic structure — •Tommaso Pincelli1,2, Tania Mukherjee1,2, Lawson Lloyd2, Jyoti Krishna3, Túlio de Castro2, Shuo Dong4, Victoria Taylor2, Yoav William Windsor1,2, Martin Wolf2, Laurenz Rettig2, and Ralph Ernstorfer1,2 — 1Institute of Optics and Atomic Physics, Technische Universität Berlin, Berlin, Germany — 2Fritz Haber Institute of the Max Planck Society, Berlin, Germany — 3Max-Born-Institut (MBI), Berlin — 4Institute of Physics, Beijing National Laboratory for Condensed Matter Physics, Beijing, China
Iron Germanium Telluride (FGT) is a van der Waals metallic ferromagnet that has shown a wealth of exotic phenomena, ranging from 2D ferromagnetism with gate-tunable Curie temperature to heavy fermion behaviour. Despite its interest, its electronic structure and the microscopic interactions giving rise to magnetic order are still poorly understood: evidence exists of both itinerant and localized magnetic behaviour, an anomaly in a purely 3d electronic system. By employing time-resolved angle-resolved photoemission spectroscopy (trARPES), we observe clear evidence of the closure of the Stoner exchange gap, a clear indication of an itinerant character of the electronic excitations. This is in contrast with previous results of quasi-equilibrium studies, which ascribed FGT demagnetization to localized excitations. We also observe, by employing frequency domain ARPES, the impact of phononic excitations, resulting in an A1g phonon strongly coupled with the bandstructure at the Brillouin zone centre.
Keywords: Fe3GeTe2; ferromagnetism; 2D materials; van der Waals crystals; ARPES