On the basis of Quantum-Monte-Carlo results the evolution of the spectral weight A(k, ω) of the two-dimensional Hubbard model is studied from insulating to metallic behavior. As observed in recent photoemission experiments for cuprates, the electronic excitations display essentially doping-independent features: a quasiparticle-like dispersive narrow band of width of the order of the exchange in...

– We have studied the chemical potential shift in La1−xSrxMnO3 as a function of doped hole concentration by core-level x-ray photoemission. The shift is monotonous, which means that there is no electronic phase separation on a macroscopic scale, whereas it is consistent with the nano-meter scale cluster formation induced by chemical disorder. Comparison of the observed shift with the shift dedu...

High radon concentrations indoors usually depend on the possibilities of radon penetration from the surrounding soil into the buildings. Radon concentrations in dwellings up to 100 kBq/m3 were found in some special regions (i.e. Schneeberg/Saxony, Umhausen/Tyrol), where the soil shows a high uranium content and additionally, a fast radon transport in the soil is possible. To reduce the radon ex...

A novel method for connecting single conductive polydiacetylene chains to single organic molecules was recently developed in order to connect molecules each other and fabricate a practical singlemolecule integrated circuit. The method was named “chemical soldering” [1]. This method uses the nanoscale control of chain polymerization of diacetylene compounds (general formula R–C≡C–C≡C–R′) in a se...

The quasiparticle spectra in the metallic rutile and insulating monoclinic phases of VO2 are shown to be dominated by local Coulomb interactions. In the rutile phase the small orbital polarization among V 3d t2g states leads to weak static but strong dynamical correlations. In the monoclinic phase the large 3d orbital polarization caused by the VuV Peierls distortion gives rise to strong static...

We consider interaction effects in a granular normal metal at not very low temperatures. Assuming that all weak localization effects are suppressed by the temperature we replace the initial Hamiltonian by a proper functional of phases and study the possibility for a phase transition depending on the tunneling conductance g. It is demonstrated for any dimension that, while at small g the conduct...

Kondo insulators are a particularly simple type of heavy electron material, where a filled band of heavy quasiparticles gives rise to a narrow band insulator. Starting with the Anderson lattice Hamiltonian, we develop a topological classification of emergent band structures for Kondo insulators and show that these materials may host three-dimensional topological insulating phases. We propose a ...

We examined the characteristics of a metal–insulator transition on a two-dimensional nonbipartite lattice when both disorders and electron interactions are present. Using a real-space renormalization group method and finite-size scaling analysis we have found that after the disordered system transits from the insulating state to the metal one, it can reenter an insulating state if there is a fu...

We study the resonating valence bond theory of the Hubbard-Heisenberg model on the half-filled anisotropic triangular lattice. Varying the frustration changes the wave vector of maximum spin correlation in the Mott insulating phase. This, in turn, changes the symmetry of the superconducting state that occurs at the boundary of the Mott insulating phase. We propose that this physics is realized ...

We present an ab initio quantum theory of the metal-insulator transition in Ti2O3. The recently developed cluster LDA+DMFT scheme is applied to describe the many-body features of this compound. The conventional single site DMFT cannot reproduce a low temperature insulating phase for any reasonable values of the Coulomb interaction. We show that the nonlocal Coulomb interactions and the strong c...