The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe

• DOI: 10.1038/s41524-021-00523-7
• Publication Date: 2021-04-29T10:05:37Z
• Authors: Đorđe Dangić; Olle Hellman; Stephen Fahy; Ivana Savić
• Keywords: Ferroics; Lattice (music)

Abstract The proximity to structural phase transitions in IV-VI thermoelectric materials is one of the main reasons for their large phonon anharmonicity and intrinsically low lattice thermal conductivity κ . However, GeTe increases at ferroelectric transition near 700 K. Using first-principles calculations with temperature dependent effective potential method, we show that this rise consequence negative expansion rhombohedral increase lifetimes high-symmetry phase. Strong induces non-Lorentzian shapes power spectra. To account these effects, implement a method calculating based on Green-Kubo approach find Boltzmann transport equation underestimates transition. Our findings elucidate influence provide guidance design better materials.