Dresden 2017 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 40: Transport III - thermal transport
MM 40.2: Talk
Wednesday, March 22, 2017, 10:30–10:45, IFW D
Ab initio investigation of the anomalous phonon softening in FeSi — •Robin Stern1 and Georg K. H. Madsen2 — 1ICAMS, Ruhr-Universität Bochum, Germany — 2Institute of Materials Chemistry, TU Wien, Austria
The anomalous softening of the acoustic phonon peak in FeSi has recently received considerable experimental attention. In our work, we investigate the effect of thermal disorder on the lattice dynamics and the filling of the narrow band gap of FeSi using density functional theory. We show, by comparing the phonon density of states from temperature-independent and temperature-dependent force constants, that thermal structural disorder together with thermal expansion explains the anomalously strong renormalization of the acoustic phonons. Furthermore, we find an intricate interplay between thermal disorder and volume in gap closure.