Berlin 2024 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 28: Focus Session: Heat transport at the nanoscale: theory meets experiment
HL 28.7: Talk
Wednesday, March 20, 2024, 12:15–12:30, EW 203
anisotropic thermal conductivity studied with the ab initio Green-Kubo approach: the example of Ga2O3 — •Shuo Zhao, Thomas A. R. Purcell, Kisung Kang, Matthias Scheffler, and Christian Carbogno — The NOMAD Laboratory at the FHI of the Max-Planck-Gesellschaft and IRIS-Adlershof of the Humboldt-Universität zu Berlin
Anisotropic heat transport is important in thermoelectric materials and electronic devices since the efficiency of heat dissipation depends on the crystal axis. [1] The anisotropic thermal conductivity is often addressed in the phonon picture, but the role of (strong) anharmonicity is rarely discussed. To clarify this question, we employ the ab initio Green-Kubo method, [2] which accounts for all anharmonic effects through ab initio molecular dynamics. By extending its applicability to anisotropic transport, we discuss the thermal conductivity for the β, α, and κ-phase of Ga2O3, promising candidate materials for field-effect transistors. Our calculations show reasonable agreement with the experiment and allow us to explain the observed anisotropic transport. In particular, we discuss the role of strong anharmonic effects beyond the phonon picture at higher temperatures. In this regard, we also analyze the role of the employed exchange-correlation functional. This study paves the way for exploring the anisotropic, strongly anharmonic systems.
[1] C. Chang et al., Science 360, 778 (2018).
[2] C. Carbogno, R. Ramprasad, and M. Scheffler, Phys. Rev. Lett. 118, 175901 (2017).
Keywords: Thermal transport; ab initio Green-Kubo; Anisotropy; Ga2O3