Search academic texts

Information × Registration Number 0118U100167, ( 0219U100034  0220U100699  ) R & D request Title Effects of correlation and frustration in strongly correlated electron and magnetic systems Head Matveev Oleh P., Кандидат фізико-математичних наук Registration Date 25-10-2018 Organization Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine popup.description1 The purpose of the project is to study the effects of strong local and nonlocal correlations in systems described by quantum lattice models of different dimensionality, by calculating and analyzing their static and dynamic properties. It is planned to investigate low-temperature properties of the quantum antiferromagnetic Heisenberg model on lattices of different geometry and dimensionality with frustration between bonds. It is aimed to construct a complex theory for such systems in the presence of strong magnetic fields and at low temperatures, and to obtain observable thermodynamic quantities, which are measured in real compounds. For this purpose, the theory of localized magnons will be applied, which is a key tool to examine the frustrated quantum Heisenberg antiferromagnets with a dispersionless single-magnon zone. The effective models for description of the frustrated quantum Heisenberg antiferromagnets will be developed by using the operator perturbation theory. It is expected that the phase transition may occur for the model on a two-layer lattice at finite temperatures and in presence of strong magnetic fields. It will be found the conditions when this phase transition can be observed. The purpose of the work also includes the analysis of phase diagrams of the frustrated quantum Heisenberg antiferromagnet on the two-layer lattices of different geometry in the ground state and examination of the behavior of a quantum critical end point when parameters of the model are changed, and study of the sublattice magnetization curves. One of the objectives is to study the effects of strong nonlocal correlations for the Falicov-Kimball model on the Bethe lattice. Detailed examination of the optical conductivity spectra and calculation of the charge susceptibility are planned for the systems with correlated hopping within the dynamical mean-field theory approach. popup.nrat_date 2024-12-10 Close