We have investigated the influence of Landau quantization both on the field and temperature dependence of some properties of singlet and triplet type4 superconductors. In particular, we consider a multichannel structure of the superconducting gap function, oscillations of the critical temperature with increasing magnetic field and a possible reentrance of superconductivity. In addition, de Haas-van Alphen-like oscillations of the specific heat and its jumps at the critical temperatures have also been analyzed.

We analyse the ground state phase diagrams of the charge orderings in narrow band materials using two eective models: (1) the spinless fermion model (t−W ) with repulsive intersite interaction (Wij > 0) and (2) the molecular crystal model with the coupling of electrons to intramolecular (crystal eld) vibrations. We present results for the case of half lled bands for d = 2 square lattice. The calculations are performed within the (broken symmetry) Hartree-Fock approximation. The study takes into consideration the eects of frustrating next-nearest--neighbour hopping (t2) on the charge ordered states in these systems. We focus on the two cases: (i) homogeneous phases and phase separations involving checkerboard charge ordering with the nesting vector Q = (π, π) only and (ii) homogeneous phases and phase separations involving two types of charge ordering: (a) checkerboard charge ordering with the nesting vector Q = (π, π), and (b) collinear (CL) charge ordering with Q = (0, π) or Q = (π, 0).

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There is ongoing, intense, research in the eld of electron charge orderings (CO) and charge density waves phenomena, due to experimental discovery of such phases in numerous important compounds. The aim of this work is to extend recent advances in the eld by studying two simple eective paradigmatic models used to describe CO in narrow band materials i.e. (i) a model of correlated electrons: the so-called tW model of spinless fermions with repulsive interaction W and (ii) the molecular crystal model with the coupling of electrons to intramolecular (crystal eld) vibrations in the static limit. The nite temperature phase diagrams are evaluated at arbitrary carriers concentration for several representative cases. Our calculations are performed within the (broken symmetry) HFA for d = 2 square lattice and arbitrary carriers concentration. In this contribution we focus on the eects of next-nearest-neighbor hopping on the CO states in these systems and the problem of phase separations involving checkerboard CO with the nesting vector Q = (π, π). The results we show here are an extension of our previous work on the subject.

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The tunneling current between the metallic tip of a scanning microscope and s-wave and p-wave superconductors in a quantizing magnetic field is investigated. The differential conductance is calculated both as a function of bias voltage at the centre of the vortex line and for varying position of the scanning tunneling microscope tip at a stable voltage.