Thermal conductivity of superlattices and ferroelectric thin films. Effect of boundary sizes and vacancies

Thermal transport in solids has recently seen great advances. This thesis focuses on thermal transport in two different interesting cases: superlattices and ferroelectric thin films. Thermal conductivity of superlattices of SrTiO3/LaCoO3 show a non-trivial change upon modification of the thickness of the repetition unit. It is shown how coherent and incoherent phonons shape this dependence and how they are affected by the structure of the superlattices. On the other hand, ferroelectric thin films of BaTiO3 and PbTiO3 with different cationic concentrations were investigated. It is proven that ferroelectric domain walls hinder thermal transport in both materials, as well as cationic defects