PhD Thesis Defense- Unai Aseguinolaza

Anharmonic effects in thermoelectric and 2D materials

Candidate: Unai Aseguinolaza

Supervisors: Ion Errea and Aitor Bergara

Research group: Quantum Theory of Materials

When: 18th of September, 10:30 am

Link to  live Streaming

Download pdf

Summary

In this thesis we study materials where anharmonicity is crucial to understand their physical properties. In the first part we have  studied high efficiency thermoelectric materials like SnSe and SnS. We have seen that non-perturbative anharmonicity is very important to understand their vibrational and thermal properties. In the second part we have analyzed the anharmonic effects in the acoustic vibrations of 2D materials. We see that the harmonic approximation completely breaks down and anharmoniciy is crucial for a proper undestanding.

Phonon spectral function of SnSe. a) Spectral function at 600 K, below the transition temperature. b) Spectral function at 800 K, above the transition temperature.