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MA: Fachverband Magnetismus
MA 24: Weyl Semimetals (joint session MA/TT)
MA 24.4: Vortrag
Dienstag, 10. März 2026, 14:45–15:00, POT/0361
Phonon-driven axial fields enable terahertz Kerr rotation in WTe2 — •Soma Dutta, Vishal Shokeen, Ruslan Chulkov, David Muradas Belinchón, M. Venkata Kamalakar, Oscar Grånäs, and Hermann Dürr — Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
Weyl semimetals provide a platform for studying the coupling between lattice dynamics and topological electronic structure through the motion of Weyl nodes and their associated Berry curvature (see Sie et al., Nature 565, 61, 2019). Here we report the observation of terahertz-frequency Kerr rotation in the non-centrosymmetric Weyl semimetal WTe2, generated in the absence of an external magnetic field. Using ultrafast pump-probe polarimetry, we identify coherent oscillations at 0.24 THz and 2.4 THz that originate from interlayer shear vibrations and optical phonon modes, respectively. The 0.24 THz shear mode exhibits maximum amplitude along the a-axis and is strongly suppressed along b, indicating an odd mirror-symmetry character. By modeling the strain-induced modification of the Weyl-node separation, we show that this shear phonon produces an axial vector potential whose sign depends on the direction of atomic displacement. Spatial gradients of this axial potential generate a pseudo-magnetic field with a sign structure that naturally accounts for the observed phase inversion. Our results provide direct evidence for phonon-driven axial electromagnetic fields in a Weyl semimetal and demonstrate a route for ultrafast control of topological optical responses through coherent lattice motion. Ab initio calculations will further clarify the Kerr response mechanism.
Keywords: Weyl semimetal; Terahertz Kerr Rotation; Shear phonons; Axial Fields; Ultrafast Topological Response