Konrad Wilczyński
supervisor: Mariusz Zdrojek
Anharmonicity is an important feature of van der Waals layered materials due to its significant impact on the thermally induced movement of atoms in the lattice – including interactions between phonons (elementary lattice vibrations) and thermal expansion. Understanding lattice dynamics is important not only from the basic research perspective but also to better interpret experimental data obtained within spectroscopic characterization and from the point of view of potential applications - including the impact of the phonon propagation on thermal conductivity.
In this work, I use first-principles modeling to study layered materials' vibrational properties, including their temperature-dependent evolution. The calculated results are used to interpret or explain available experimental results. The studies are performed as a function of different structural modifications - interesting from the point of view of potential applications. Here, I consider the following modifications:
- The number of layers in thin multi-layered films,
- Effects of substrate-induced strain and charge doping,
- Formation of structural defects.
As representative examples, multi-layered tungsten disulfide (WS2) and defected titanium disulfide (TiS2) are chosen.