Niyazi, A. (2022). Collective modes in ordered phases of multi-orbital Hubbard model [Dissertation, Technische Universität Wien]. reposiTUm. https://doi.org/10.34726/hss.2022.87705
Multi-orbital Hubbard model is well known for its rich phase diagram, is commonly used for simulation at real materials. Dynamical susceptibilityis related to spectrum of collective excitations in solids. In this thesis we present a dynamical mean-field (DMFT) study of dynamical susceptiblity in multi-orbital Hubbard model. By varying model parameters (band asymmetry,crystal field, temperature) we realize transition between various phases such as triplet excitonic condensate, spin state order (solid), supersolid or anti ferromagnets. We analyze the behavior of relevant dynamical susceptibilities across these transitions, which either breaks continuous or discrete symmetries. Besides revealing the rich physics of the studied model, our results show how DMFT susceptibilities can be used to identify approximate (weakly broken) symmetries and incipient instabilities.modes are found in response to such perturbations. The present work demonstrates the feasibility and utility of DMFT linear response calculations.
