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The competition between kinetic energy and Coulomb interactions in electronic systems can lead to complex many-body ground states with competing superconducting, charge density wave, and magnetic orders. Here we study the low temperature…
We describe a self consistent magnetic tight-binding theory based in an expansion of the Hohenberg-Kohn density functional to second order, about a non spin polarised reference density. We show how a first order expansion about a density…
Ground state properties of the spin$-1/2$ Falicov-Kimball model on a triangular lattice in the presence of uniform external magnetic field are explored. Both the orbital and the Zeeman field-induced effects are taken into account and in…
The quantum dynamics of quasi-one-dimensional ring with varying electron filling factor is investigated in presence of external electric field. The system is modeled within Hubbard Hamiltonian with attractive Coulomb correlation, which…
Exact ground states of interacting electrons on the diamond Hubbard chain in a magnetic field are constructed which exhibit a wide range of properties such as flat-band ferromagnetism and correlation induced metallic, half-metallic or…
We investigate the emergence of ferromagnetism in the two-dimensional metal-halide CoBr$_2$, with a special focus on the role of electronic correlations. The calculated phonon spectrum shows that the system is thermodynamically stable…
The magnetic character of the ground-state of two electrons on a double quantum dot, connected in series to left and right single-channel leads, is considered. By solving exactly for the spectrum of the two interacting electrons, it is…
An important consequence of the discovery of giant magnetoresistance in metallic magnetic multilayers is a broad interest in spin dependent effects in electronic transport through magnetic nanostructures. An example of such systems are…
The study of multi-band superconductivity is relevant for a variety of systems, from ultra cold atoms with population imbalance to particle physics, and condensed matter. As a consequence, this problem has been widely investigated bringing…
Metallic magnetism is both ancient and modern, occurring in such familiar settings as the lodestone in compass needles and the hard drive in computers. Surprisingly, a rigorous theoretical basis for metallic ferromagnetism is still largely…
These are introductory lectures to some aspects of the physics of strongly correlated electron systems. I first explain the main reasons for strong correlations in several classes of materials. The basic principles of dynamical mean-field…
Using a positive semidefinite operator technique one deduces exact ground states for a zig-zag hexagon chain described by a non-integrable Hubbard model with on-site repulsion. Flat bands are not present in the bare band structure, and the…
Metal insulator transitions driven by local Coulomb interactions are among the most fascinating phenomena in condensed matter physics. They occur in a large variety of transition metal compounds. Most of these strongly correlated materials…
We investigate the interplay of ferroelectricity and quantum electron transport at the nanoscale in the regime of Coulomb blockade. Ferroelectric polarization in this case is no longer the external parameter but should be self-consistently…
A new two-pole approximation, which allows to describe the transition from an insulating state to a metallic one at increase of bandwidth, and also the observable in some compounds transition from a metalic state to an insulating one with…
A semi-empirical formalism based on the second moment tight binding approach, considering two bands is presented for deriving interatomic potentials for magnetic d-band materials and transition metal alloys. It incorporates an empirical…
We consider the proximity effects in hybrid superconductor (S) - ferromagnet (F) structures drawing attention to the induced ferromagnetism of the S metal. The analysis is based on a quasiclassical theory of proximity effect for metals in…
Entanglement has been widely investigated in condensed matter systems since they are considered good candidates for developing quantum technologies. Additionally, entanglement is a powerful tool to explore quantum phase transitions in…
The three dimensional periodic Anderson model is studied with Quantum Monte Carlo. We find that the cross-over to the Kondo singlet regime is remarkably sharp at low temperatures, and that the behavior of magnetic correlations is…
Motivated by the search for design principles of rare-earth-free strong magnets, we present a study of electronic structure and magnetic properties of the ferromagnetic metal Fe3GeTe2 within local density approximation (LDA) of the density…