Spectroscopy of strongly correlated materials: cluster approach

Abstract: The materials with strong electronic correlations are one of the most fascinating problems in modern solid state physics. They exhibit a variety of intriguing properties and phenomena, that are very sensitive to a change of control parameters (e.g. magnetization, temperature, pump-probe time delay, pressure). This remarkably rich physics is a consequence of competing kinetic and Coulomb energies of electrons, which makes a theoretical description of these materials and their electronic structure a challenging problem.
In the present talk I will discuss recent progress in theoretical methods that can help to interpret results of spectroscopic experiments and obtain a deeper understanding of the underlying physics. I will discuss recently developed approaches based on combination of material-specific density-functional-based model parameters and explicitly solvable many-body model Hamiltonians, capturing effects caused by electronic correlations.
Using these methods we can calculate X-ray absorption spectra (XAS) of LaCoO₃ and its surface effects. I will also show XAS calculations for magnetite Fe₃O₄ and X-ray emission spectroscopic calculations (XES) for metal-organic framework CPO-27-Ni.