We propose a mechanism of superconductivity in which the order of the ground state does not arise from the usual Landau mechanism of spontaneous symmetry breaking but is rather of topological origin. The low-energy effective theory is formulated in terms of emerging gauge fields rather than a...

The electronic structure of strontium ferrite Sr<Subscript>3</Subscript>Fe<Subscript>2</Subscript>O<Subscript>6</Subscri pt> was calculated using the tight-binding linear muffin-tin orbital method (TB LMTO) in the local spin density approximation of density functional theory with Coulomb correlations correction (LSDA+U). The semiconducting character of the...<//subscri></subscript></subscript></subscript>

We discuss the hysteretic behavior of the field-induced variations of the microwave surface resistance in superconductors in the critical state. Measurements have been performed in a bulk sample of Nb and a powdered one at different values of the temperature. We discuss a model, based on the...

Using Scanning Tunneling Microscope at low temperature we explore the superconducting phase diagram in the π-band of the two-band superconductor MgB<Subscript>2</Subscript>. In this band the peculiar shape of the local tunneling spectra and their dynamics in the magnetic field reveal the complex character of the...</subscript>

The complete phase diagrams of the antiferromagnetic spin-2 Blume-Capel Ising system is studied on the Bethe lattice by the use of exact recursion relations. In order to specify the states of the system, i.e. the different spin configurations, the ground state phase diagram is obtained on the...

We report on the microwave surface resistance of two polycrystalline Mg<Superscript>11</Superscript> B<Subscript>2</Subscript> samples; one consists of pristine material, the other has been irradiated at very high neutron fluence. It has already been reported that in the strongly irradiated sample the two gaps merge into a single value. The mw...</subscript></superscript>