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HL: Fachverband Halbleiterphysik

HL 23: Ultra-fast phenomena

HL 23.7: Vortrag

Dienstag, 17. März 2020, 11:30–11:45, POT 112

Femtosecond electron diffuse scattering probes momentum-resolved phonon dynamics in black phosphorus — •Hélène Seiler¹, Daniela Zahn¹, Marios Zacharias¹, Patrick Hildebrandt¹, Thomas Vasileiadis¹, Will Windsor¹, YingPeng Qi¹, Maciej Dendzik¹, Christian Carbogno¹, Claudia Draxl², Fabio Caruso², and Ralph Ernstorfer¹ — ¹Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany. — ²Department of Physics, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 6, 12489 Berlin, Germany

We employ femtosecond electron diffuse scattering in combination with first principle calculations to reveal the consequences of atomic and electronic structure anisotropy on phonon dynamics in prototypical anisotropic semiconductor black phosphorus. We show the presence of two dominant channels for electron-phonon scattering, namely intravalley scattering within the Gamma valley and intervalley scattering towards the Y valley. Phonons subsequently build up along the Gamma-X path over tens of picoseconds, as a result of phonon-phonon coupling. These measurements provide insights into the origin of anisotropic non-equilibrium properties with unprecedented level of detail. Our work provides direct experimental evidence that a transient nonthermal phonon distribution exists for tens of picoseconds in black phosphorus and highlights the key role of phonon-phonon scattering in phonon thermalization. That thermalization in black phosphorus is limited by phonon-phonon scattering is expected to have consequences on heat and electrical transport properties.