Abstract:
First part of this talk, we study a model of the exact (2+1)-dimensional case. We employ the massless Gross-Neveu model at finite temperature and density, to study the superconductivity and superconducting instability. Both an attractive and repulsive cases are considered. Our investigation is related to the superconductivity in (2+1)-dimensional two-band systems like MgB₂ or intercalated graphite.
Second part of this talk, we examine a quasi-(2+1) dimensional model. In this model, the intra-layer particle dynamics is described by a (2+1)-dimensional Gross-Neveu-type four-body contact interaction model, while inter-layer particle motions will be caused by a hopping term with a transfer parameter t. ( Hence, the model of the second part will include that of the first part. ) Especially, we examine the effects of non-vanishing t, chemical potential mu, and a mass parameter m which will give a gap at a conical intersection point of the relativistic band dispersion, in the BCS s-wave (scalar) superconducting gap function Delta.