2017/08/31 by Manfred Ersfeld, Frank Volmer, Pedro Melo +7 · 35 citations
Chemistry · Engineering · Materials Science · Physics and Astronomy · #2D Materials and Applications #Atomic physics #Chemistry #Condensed matter physics #Electron #Optics #Perovskite Materials and Applications #Phonon #Phonon scattering #Physics #Scattering #Spin polarization #Topological Materials and Phenomena #cond-mat.mes-hall
paper · pdf · doi:10.1021/acs.nanolett.9b01485
published in Nano Letters 19(6), 4083-4090 (American Chemical Society) · 18 pages, 17 figures
arxiv created 2019/04/08 · openalex publication_date 2019/05/07 · arxiv updated 2019/06/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
. These long lifetimes are accompanied by an intriguing temperature-dependence of the Kerr amplitude, which increases with temperature up to 50 K and then abruptly switches sign. Using ab initio simulations, we explain the latter behavior in terms of the intrinsic electron-phonon coupling and the activation of transitions to secondary valleys. The phonon-assisted scattering of the photoexcited electron-hole pairs prepares a valley spin polarization within the first few ps after laser excitation. The sign of the total valley magnetization, and thus the Kerr amplitude, switches as a function of temperature, as conduction and valence band states exhibit different phonon-mediated intervalley scattering rates. However, the electron-phonon scattering on the ps time scale does not provide an explanation for the long spin lifetimes. Hence, we deduce that the initial spin polarization must be transferred into spin states, which are protected from the intrinsic electron-phonon coupling, and are most likely resident charge carriers, which are not part of the itinerant valence or conduction band states.