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O: Fachverband Oberflächenphysik

O 16: Ultrafast Electron Dynamics at Surface and Interfaces II

O 16.3: Vortrag

Montag, 27. März 2023, 15:30–15:45, TRE Phy

Photoinduced dynamics of flat bands in the kagome metal CoSn by TR-ARPES — •Denny Puntel¹, Wibke Bronsch², Manuel Tuniz¹, Mingu Kang³, Paul Neves³, Shiang Fang³, Efthimios Kaxiras^4,5, Joseph G. Checkelsky³, Riccardo Comin³, Fulvio Parmigiani^1,2, and Federico Cilento² — ¹Dipartimento di Fisica, Università degli Studi di Trieste, Trieste (Italy) — ²Elettra - Sincrotrone Trieste S.C.p.A., Trieste (Italy) — ³Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA — ⁴Department of Physics, Harvard University, Cambridge, MA, USA — ⁵John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA

In kagome systems, the geometry of the lattice localises the electrons in real space, enhancing the correlations and giving rise to flat bands. In CoSn two flat bands with nontrivial topological character lie below the Fermi level [1]. In order to study the response of the localisation mechanism to impulsive excitation, we performed the first time- and angle-resolved photoelectron spectroscopy study on CoSn. At temporal overlap we observe an increase in the electronic temperature, along with a shift and broadening of the flat bands by few meV. A smaller broadening of the flat band persists for the whole duration of the investigated time delay range (about 6 ps). A possible explanation for this broadening is the partial disruption of the real-space electron localisation, because of the increased mobility of the carriers due to the energy injected by the infrared pump pulse.

[1] M. Kang et al., Nat. Commun. 11, 4004 (2020)