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MON: Monday Contributed Sessions
MON 23: Poster Session: Fundamental Aspects and Model Systems
MON 23.29: Poster
Monday, September 8, 2025, 18:30–20:30, ZHG Foyer 1. OG
Limits of the anomalous-velocity description for currents in solid state systems driven by ultrafast pulses — •Jelena Schmitz, Adrian Seith, Jan Wilhelm, and Ferdinand Evers — Institute of Theoretical Physics and Regensburg Center for Ultrafast Nanoscopy, University of Regensburg, Germany
The current response of solids to electric fields E(t) is often described using a quasi-classical current approximation including an anomalous velocity term containing the Berry curvature Ωn(k) [1], j(t) = ∫BZ dk/(2π)^d q ∑n (∂є_n(k) / ∂_k+ q E(t) ×Ω_n(k)) f_n^(0)(k) , where fn(0)(k) denote the (initial) band occupations and єn(k) the dispersion. To test the limits of the quasi-classical descriptions for ultrafast and strong driving fields, we compare Eq. (1) with results from a quantum mechanical calculation using the Semiconductor Bloch equations (SBE) [2,3]. By deriving Eq. (1) from the SBE, we determine the parametric regime of validity of the quasi-classical description. The small dimensionless parameters that control the domain of applicability are weak fields and slow driving in comparison to the system dependent effective gap. We confirm our analytic predictions by comparing Eq. (1) to numerically exact solutions of the SBE using a two band massive Dirac Hamiltonian as our model system. [1] Xiao, D. et. al., Rev. Mod. Phys. 82, 1959 (2010) [2] Schmitt-Rink, S. et. al., Phys. Rev. B 37, 941 (1988) [3] Wilhelm, J. et. al., Phys. Rev. B 103, 125419 (2021) [4] https://github.com/ccmt-regensburg/CUED/
Keywords: Berry-curvature; anomalous-velocity; Semiconductor-Bloch Equations; Ultrafast dynamics; photocurrent