Related papers: Insulator-to-Metal Transition in Selenium-Hyperdop…
We investigate a quarter-filled two-band Hubbard model involving a crystal-field splitting, which lifts the orbital degeneracy as well as an inter-orbital hopping (inter-band hybridization). Both terms are relevant to the realistic…
The mechanisms that drive metal-to-insulator transitions (MIT) in correlated solids are not fully understood. For example, the perovskite (PV) SrCoO3 is a FM metal while the oxygen-deficient (n-doped) brownmillerite (BM) SrCoO2.5 is an…
Metals with values of the resistivity and the Hall coefficient much larger than typical ones, e.g., of sodium, are called semimetals. We suggest a model for semimetals which takes into account the strong Coulomb repulsion of the charge…
We consider a heterostructure of a metal and a paramagnetic Mott insulator using an adaptation of dynamical mean field theory to describe inhomogeneous systems. The metal can penetrate into the insulator via the Kondo effect. We investigate…
We present a comprehensive optical study of the narrow gap $FeSb_2$ semiconductor. From the optical reflectivity, measured from the far infrared up to the ultraviolet spectral range, we extract the complete absorption spectrum, represented…
Hyperdoping consists of the intentional introduction of deep-level dopants into a semiconductor in excess of equilibrium concentrations. This causes a broadening of dopant energy levels into an intermediate band between the valence and…
Structural and electronic properties of pristine and transition metal doped ZnS monolayer are investigated within the framework of density functional theory. The pristine ZnS monolayer is showing direct band gap of about 2.8 eV. The…
It was recently demonstrated the possibility to tune, through the application of a control gate voltage, the superconducting properties of mesoscopic devices based on Bardeen-Cooper-Schrieffer metals. In spite of the several experimental…
The Superconductor-to-Insulator Transition (SIT) in two-dimensional superconductors occurs due to a competition between superconductivity, quantum interferences, Coulomb interactions and disorder. Despite extensive theoretical and…
We report infrared studies of the insulator-to-metal transition (IMT) in GaAs doped with either magnetic (Mn) or non-magnetic acceptors (Be). We observe a resonance with a natural assignment to impurity states in the insulating regime of…
We present a microscopic picture rationalizing the surprisingly steep decrease of the band gap with temperature in insulators, crystalline or otherwise. The gap narrowing largely results from fluctuations of long-wavelength optical…
A band gap for electronic states in crystals governs various properties of solids, such as transport, optical and magnetic properties. Its estimation and control have been an important issue in solid state physics. The band gap can be…
We present a first-principles study of semiconducting carbon nanotubes adsorbed on the unpassivated Si(100) surface. We have found metallicity for the combined system caused by n-doping of the silicon slab representing the surface by the…
First-principles band structure investigations of the electronic, optical and magnetic properties of Mo-doped In$_2$O$_3$ reveal the vital role of magnetic interactions in determining both the electrical conductivity and the Burstein-Moss…
It is shown that recent experiments indicating a metal-insulator transition in 2D electron systems can be interpreted in terms of a simple model, in which the resistivity is controlled by scattering at charged hole traps located in the…
Transport and magnetic properties have been systematically investigated for SmMnAsO_{1-x} with controlled electron-doping. As the electron band-filling is increased with the increase of oxygen deficiency (x), the resistivity monotonically…
The phase diagram of the high-Tc cuprates is dominated by the Mott insulating phase of the parent compounds. As we approach it from large doping, a standard Fermi-liquid gradually turns into a bad non-Fermi liquid metal, a process which…
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…
Superconductivity in a doped topological insulator (TI) is a very interesting phenomenon and constitute a new finding of the modern day condensed matter physics. Here we have investigated the physical and transport properties of such an…
We show that optically pumped semiconductors can exhibit superconductivity. We illustrate this phenomenon in the case of a two-band semiconductor tunnel-coupled to broad-band reservoirs and driven by a continuous wave laser. More…