The TRR 227 kindly invites you to the joint Colloquium of the TRR 227 & FU Physics Department.

Speaker: Prof. Dr. Sebastian F. Maehrlein,
Helmholtz-Zentrum Dresden-Rossendorf; Technische Universität Dresden, Institut für Angewandte Physik; Fritz-Haber-Institut der Max-Planck-Gesellschaft

Title: Driving coherent phonon-phonon angular momentum transfer via lattice anharmonicity

Abstract:

I will introduce the basics of THz-driven lattice trajectory control for IR- and Raman-active modes, and extend it by tailored THz helicity states to establish helical or chiral nonlinear phononics. By this, we coherently control angular momentum transfer between two lattice modes by the inverse process of anharmonic decay abundant in nature. The observed rotational phonon-phonon Umklapp scattering enforces the conservation of quantized crystal angular momentum, as dictated by the crystal’s discrete rotational symmetry. [see also arXiv:2503.11626]