Ab initio prediction of thermomagnetic and thermoelectric transport phenomena in 3d and 2d materials

Abstract

In this work we study the thermomagnetic and thermoelectric transport phenomena in 3d and 2d crystals. We first present the general theory for transport in presence of electric and magnetic external fields. In this context, we introduce the linearised Boltzmann Transport Equation and the Kubo formalism, with a focus on their derivation from first-principles and on the ab-initio evaluation of their main ingredients. Here, a particular emphasis is given to the development of an efficient approach to determine magneto-transport coefficients, that firmly relies on our highly scalable and strongly optimized computational implementation. Then, we apply the theory to three different systems: bulk p-doped diamond, graphene and the tetrahedrite compound Cu12Sb4S13. Each one of these systems, beside being of interest for technological applications, poses its own challenge to the calculation of transport properties. p-doped diamond presents a complex interplay between the electronic and vibrational properties, that has prevented detailed experimental investigation to extract the true value of transport observables; in graphene, the electrons near the Dirac cone have very large momenta that generate non-trivial trends and values of the transport properties, that are in sharp contrast with known behaviours of traditional semiconductors; finally, the tetrahedrite system dis-plays a complex crystal structure stabilized by temperature so that the description of its transport properties requires a proper sampling of the electron-ion dynamics of the system. In this perspective, the theoretical study of these systems and the comparison with experimental data serve both purposes of increasing the knowledge of specific material properties and of testing the theory on challenging cases.

Date of Award	1 Jul 2021
Original language	English
Awarding Institution	King's College London
Supervisor	Nicola Bonini (Supervisor) & Cedric Weber (Supervisor)