Regensburg 2022 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 23: Computational Materials Modelling: Magnetic & Electrical Properties

MM 23.8: Vortrag

Mittwoch, 7. September 2022, 17:45–18:00, H44

Spin fluctuations and Wigner thermal transport in thermoelectric skutterudites — •Enrico Di Lucente¹, Michele Simoncelli², and Nicola Marzari¹ — ¹Theory and Simulation of Materials (THEOS) and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland — ²TCM Group, Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE UK

Skutterudites are highly promising functional materials due to their peculiar thermoelectric and magnetic properties. We elucidate the complex fenomenology that takes place in these materials both in terms of spin fluctuations and in the crossover from a Peierls-Boltzmann to a Wigner thermal transport regime, where tunneling of phonon wavepackets emerges. We first study the electronic structure using the state-of-the-art DFT+Hubbard theory to uncover multiple self-consistent magnetic and charge disproportionated configurations. While the lowest energy state is antiferromagnetic but metallic, paramagnetic fluctuations captured through a special quasi random structure open a small gap of 61 meV, in good agreement with experiments. Moreover, in going from the parent compound to the related filled skutterudite, a transition from a Peierls-Boltzmann to a Wigner thermal transport regime arises, where, at working temperature of the devices, the tunneling of phonon wavepackets becomes as relevant as the drifting diffusion.