Matteo COSTA

PhD Student

Resarch activities at CPHT: Condensed Matter

Research interests: Strongly correlated materials, ab initio simulations, magnetism, spin-orbit coupling, superexchange mechanisms, multipolar interactions.

Thesis:  "Multipolar orders in correlated insulators."
Advisor: Leonid Poyurovskiy

Abstract

My research focuses on a particular type of strongly correlated materials: correlated insulators composed of heavy elements, which exhibit unusual ordered phases at low temperatures. Using an ab initio methodology developed by a group at the CPHT in collaboration with international partners, it is currently possible to evaluate the superexchange interactions between multipolar moments. However, this approach allows to derive a complete low-energy model for multipolar systems only in the strongly insulating limit. Our objective is to extend its applicability to insulators close to the Mott transition by integrating higher-order superexchange contributions as well as electron-lattice coupling. These improvements should make it possible to study systems such as transition metal halides and iridium-based perovskites. To conclude, we also employ Monte Carlo simulations within mean field approximation and linear response theory to compute thermodynamic observables and magnetic excitation spectra at finite temperatures.

Publication