Seminário Geral: Signatures of phonon hydrodynamics in thermal conductivity
- Palestrantes: Profa. Valentina Martelli - IF/USP
Sobre este evento
The hydrodynamic regime of phonon flow in a crystal is a wave-like transport regime where phonons do not degrade their momentum. This regime was identified decades ago  and is gaining renewed attention in the context of graphene-like two-dimensional systems  motivated by the increasing demand for efficient heat removal from nanoelectronic devices .
The hydrodynamic flow is revealed in solids by the presence of the second sound and the Poiseuille flow of phonons. The latter can be observed studying thermal conductivity, where a faster-than cubic temperature dependence in a temperature window below the peak is the hallmark of this regime.
In this seminar, I will revise the scattering events that determine the finite thermal conductivity in insulating crystals (Normal, Umklapp, impurities), discussing under which conditions the Poiseuille flow displays in thermal transport. Finally, I will discuss our recently published results on the study of thermal conductivity of SrTiO3 , where the emergence of this phenomenon is ascribed to an enhanced space of three-phonon events that conserve momentum, allowing to attain the stricted precondition for the emergence of the hydrodynamic flow without recurring to a high purity sample.
 Beck H. et al. “Phonon hydrodynamics in solids.” Phys status solidi (a) (1974)
 Lee S. et al. “Hydrodynamic phonon transport in suspended graphene” Nature Comm (2015)
 Cahill D., et al. “Nanoscale thermal transport. II. 2003–2012.” Appl Phys Rev 1.1 (2014)
 Martelli V., et al. “Thermal transport and phonon hydrodynamics in strontium titanate.” Phys Rev Lett (2018)