Dresden 2026 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 98: Ultrafast electron dynamics at surface and interfaces IV
O 98.5: Vortrag
Freitag, 13. März 2026, 10:45–11:00, TRE/MATH
Ultrafast manipulation of topological transport properties in Td-MoTe2 via coherent phonon excitation — •Huimin Wang1, Matthew Day2,3, Juan Aranzadi1, James McIver2,3, and Michael Sentef1 — 1Institute for Theoretical Physics and Bremen Center for Computational Materials Science, University of Bremen, Bremen, Germany — 2Department of Physics, Columbia University, New York, NY, USA. — 3Max Planck Institute for the Structure and Dynamics of Matter, CFEL, Hamburg, Germany
Ultrafast control of topological properties in quantum materials has emerged as a promising route toward dissipative-free and fast optoelectronic functionalities. In type-II Weyl semimetals such as Td-MoTe*, selective photoexcitation of coherent phonons offers an efficient non-thermal pathway to drive topological phase transitions by modifying lattice symmetry. Yet the microscopic origin of the laser-induced interlayer shear mode*central to this process*remains unclear, with both electron*phonon coupling (EPC) and strong phonon anharmonicity expected to contribute. Here, using real-time TDDFT combined with non-adiabatic molecular dynamics, we map out the excitation pathways of this shear mode under varying photon energies, polarizations, and field strengths. We reveal cooperative EPC and phonon*phonon mechanisms that enable control of the phonon phase and amplitude. The resulting lattice dynamics induce shifts of Weyl node positions and associated nonlinear photocurrents, providing insight into observed ultrafast Hall responses.[1]Nature 565, 61*66 (2019). [2]Nat. Commun., vol. 12, p. 1885, 2021.[3]Phys. Rev. X, vol. 9, no. 2, p. 021036, 2019.
Keywords: Non-equilibrium dynamics; Coherent phonons; Topology; Phase transition; Ultrafast laser