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TT: Fachverband Tiefe Temperaturen

TT 68: Graphene: Electronic structure, excitations, etc. – Poster (joint session O/TT)

TT 68.1: Poster

Mittwoch, 11. März 2026, 18:00–20:00, P2

Strong-Field Bloch Electron Interferometry for Band-Structure Retrieval — •Tamara Pröbster, Tobias Weitz, Christian Heide, and Peter Hommelhoff — Friedrich-Alexander-Universität Erlangen-Nürnberg, Department Physik, Staudtstr. 1, 91058 Erlangen

Strong optical fields drive electrons in solids far from equilibrium, enabling access to ultrafast quantum dynamics that directly reflect the underlying band structure. When Bloch electrons in graphene are exposed to an intense few-cycle laser field, they undergo coherent intraband motion during which they accumulate a quantum phase determined by the local band curvature. If this laser-driven trajectory encounters an avoided crossing between the valence and conduction bands, the electron wave packet can coherently split via a Landau-Zener transition. In our work, we exploit pairs of such transitions to realize strong-field Bloch electron interferometry, forming an interferometric sequence fully embedded in the electronic band structure. The resulting interference encodes band information in the phase-dependent photocurrent. We retrieve the Fermi velocity of graphene near the K points as 1.07 ± 0.04 nm·fs⁻¹, in excellent agreement with theoretical expectations. Our results establish strong-field Bloch electron interferometry as a general and versatile approach for band-structure reconstruction under ambient conditions. Because the method relies solely on ultrafast optical driving and detection, it is naturally suited for tracking light-induced modifications of electronic structure with femtosecond temporal resolution.

Keywords: Graphene; Few-cycle laser fields; Carrier envelope phase effects; Band structure retrieval; Light-driven band-structure dynamics