Regensburg 2019 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 46: Ultra-fast phenomena
HL 46.8: Talk
Friday, April 5, 2019, 11:30–11:45, H31
Ultrafast lattice dynamics in thin film black phosphorus — •Patrick-Nigel Hildebrandt1,2, Daniela Zahn1, Thomas Vasileiadis1, Helene Seiler1, Yingpeng Qi1, and Ralph Ernstorfer1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, Berlin, Germany — 2Humboldt-Universität zu Berlin, Germany
We study the ultrafast lattice dynamics of thesemiconductor black phosphorus after photoexitation. Using femtosecond electron diffraction, we obtain a time-resolved picture of the electron-lattice equilibration and the subsequent relaxation of a non-thermal phonon population in an anisotropic material. Along the in-plane directions, armchair and zigzag, we measure an anisotropic Debye-Waller-Factor. The time-dependence of the average mean-square displacement reveals anisotropic phonon relaxation. This shows that the structural anisotropy of black phosphorus leads to anisotropic lattice dynamics, which is tentatively explained by different phonon density of states with armchair- or zigzag-polarization.