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Research subjects at department 23

Macroscopic quantum phenomena of strongly correlated and disordered electrons in crystalline solids

Most of macroscopic properties of solids at low temperatures is determined by valence electrons and their interactions. The microscopic behavior of electrons is governed by the laws of quantum mechanics, while the electron gas on macroscopic distances may mostly be characterized by classical thermodynamics. Long-range quantum coherence due to electron correlations may, however, lead to macroscopically observable effects and emergence of macroscopic quantum states such as magnetism or superconductivity.  The whole text »

Far-from-equilibrium transport in quasi-1D structures

Mechanical and thermal properties of out-of-equilibrium media containing active particles are investigated within the theoretical framework of stochastic thermodynamics. We study effective forces from such systems to attached and externally controlled probes, and we relate anomalous features of the forces to non-equilibrium thermodynamic and kinetic properties of the medium itself. We also consider non-mechanical probing like the measurement of heat response to variations in temperature or chemical potentials.   The whole text »

Non-equilibrium dynamics of electrons and charge or energy transfer in nanoscopic systems

Our research is focused on time-dependent electronic processes in nanoscopic systems. We study tunneling of electrons through bridges between massive metallic leads under strongly non-equilibrium conditions given by the electric bias between both leads and by rapid changes of the acting fields or of the boundary conditions (switching or modification of the tunneling junctions). The leads being transition metals have a complex spectral structure and may be in a magnetic state.  The whole text »

Ab-initio calculations of electronic structure and material properties

The electronic structure of complex materials with unusual properties is studied with ab-initio methods based on the density-functional theory (DFT). The calculations of the electronic structure are used to predict new materials with application potential. We have developed means that allow us to take into account various forms of disorder, relativistic effects as well as correlation-induced dynamical fluctuations. The effects of strong electron correlations are described in the framework typically referred to as DFT+DMFT that builds on material-specific Hubbard models which are solved by the dynamical-mean-field theory (DMFT). We study alloys, surfaces, individual atoms adsorbed on surfaces, as well as various interfaces, interlayers and multilayers. We concentrate on magnetic materials and on compounds containing heavy elements from the lower parts of the periodic table. Besides the standard ways of representing the electron wave functions (TB-LMTO, FP-LAPW), a real-space ab-initio code based on finite-elements method and pseudopotentials is being developed. It will be applicable to nonperiodic structures even in the case of broken charge neutrality.   The whole text »