Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 93: Focus Session: Structural Dynamics in Nanoscale Materials, Probed by Ultrafast Electron Pulses I
O 93.8: Vortrag
Donnerstag, 15. März 2018, 12:45–13:00, HE 101
Probing the interatomic potential of solids with strong-field nonlinear phononics — •A. von Hoegen1, R. Mankowsky1, M. Fechner1, M. Först1, and A. Cavalleri1,2 — 1Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany — 2Department of Physics, University of Oxford, Clarendon Laboratory, Oxford OX1 3PU, UK
Few-cycles optical pulses at mid-infrared and terahertz frequencies have enabled large amplitude excitation of vibrational modes in solids, and with it the dynamical control of material properties. So far, these applications have relied on second-order phonon nonlinearities that are dominant at field strength near 1 MV/cm. Under strong-field excitation (>20 MV/cm) the A1 (transverse optical) phonon mode in the ferroelectric material LiNbO3 can be driven to even larger amplitudes in order to explore higher-order lattice nonlinearities. The time resolved response to this excitation shows phonon harmonics up to the 5th order, extending the well-known physics of higher-order harmonic generation in optics to phononics. Beyond, the time-resolved measurement of the atomic trajectories far from equilibrium allows to reconstruct the anharmonic interatomic potential of the driven mode.