Condensed Matter Seminar - Exploring thermal transport in complex oxides

Heat transport investigations can reveal information about phonon dynamics and collective transport regimes in an insulator. In this talk, I will discuss the insights and implications of the features observed in the thermal transport of two representative perovskite-type complex oxides, SrTiO3 and BaBiO3. The first compound has gathered fundamental research efforts across different topics, such as superconductivity, thermoelectricity, and ferroelectricity [1-2]. Thermal transport in single crystalline SrTiO3 revealed the presence of the Poiseuille flow of phonons at low temperatures and a high-temperature diffusivity approaching the Planckian limit (τ=ℏ/kBT) [3]. The findings pointed to the role of the lattice degrees of freedom and specific phonon modes in setting and manipulating the heat conduction profile. The second one, BaBiO3, is the parent compound of the first high-Tc superconductor without transition metal ions. Its undoped insulating phase has an origin yet to be understood. Our very recent investigations of thermal conductivity in high-quality single crystals of BaBiO3 revealed an efficient suppression of heat transfer at high temperatures and a glass-like behaviour at low temperatures, suggesting an exceptionally high anharmonicity which could be at the base of phonon-mediated emerging phenomena [4].

REFERENCES
1. X. Lin et al, Phys. Rev. X, 3, 021002 (2013).
2. D. Bäuerle et al., Condensed Matter, 38, 335 (1980).
3. V. Martelli et al., Phys. Rev. Lett. 120, 125901 (2018)
4. Henriques et al. unpublished.