TY - THES ID - 135154303 TI - Topological Effects in 2D Strongly Correlated Electron Systems AU - Mellaerts, Simon AU - Locquet, Jean-Pierre AU - KU Leuven. Faculteit Wetenschappen. Opleiding Master of Physics (Leuven) PY - 2020 PB - Leuven KU Leuven. Faculteit Wetenschappen DB - UniCat UR - https://www.unicat.be/uniCat?func=search&query=sysid:135154303 AB - This master thesis studies the fundamental behavior of strongly correlated electron systems (SCES) reduced to a two-dimensional (2D) form. Strongly correlated systems are known to exhibit a rich variety of phenomena, e.g. heavy fermions, metal-insulators transitions, high-temperature superconductivity, etc. The dimensionality reduction of SCES is expected to enhance these correlation effects drastically, while quantum and thermal fluctuations are expected to acquire a more dominant role in 2D systems. This competition between the tendency to order and fluctuations might reveal new exotic systems, and a better understanding of the fundamental physics in these systems. Furthermore, many two-dimensional systems exhibit a Dirac cone in their electronic band structure which is often accompanied with non-trivial topological states. Consequently, these 2D SCES provide an unexplored playground where there is an interesting interplay of relativistic dispersion, strong correlations, and topological ordering. To explore this novel fundamental playground a theoretical study based on first-principle calculations is performed on vanadium sesquioxide V2O3. Three-dimensional bulk V2O3 is known as a SCES where there is a low-temperature non-isostructural metal-insulator transition (MIT), and a high-temperature isostructural MIT upon Cr-doping. Recent first-principle calculations combined with effective Hamiltonian analysis predict 2D single-atomic layer V2O3 with honeycomb-kagome (HK) lattice structure to be a magnetic Chern insulator at room-temperature. A first step in this master thesis is to verify the predictions of 2D HK V2O3 in the literature, followed by a more thorough density functional theory (DFT) based study of its physical properties. The structural stability is studied dynamically, thermally and mechanically. The electronic and orbital structure are investigated by the use of various exchange-correlation functionals accounting for the strong correlation effects present in the system. The second part of this thesis focuses on the type of realization of the quantum anomalous Hall effect. The magnetic properties are determined by DFT complemented by Monte-Carlo simulations, followed by a tight-binding calculation to study the low-energy physics and the topological nature of the band structure. This also led to proposing a unification scheme for this special type of systems, called Dirac half-metals. The last part focuses on the experimental feasibility of the 2D HK V2O3 monolayer by the search for an optimal substrate, followed by a strain study. ER -