Bose-Einstein condensation in quasi-2D systems: applications to high Tc superconductivity
We describe high-Tc superconductivity in layered materials within a BCS theory as a BEC of massless-like Cooper pairons satisfying a linear dispersion relation, and propagating within quasi-2D layers of finite width defined by the charge distribution about the CuO_2 planes. We obtain a closed formula for the critical temperature, Tc, that depends on the layer width, the binding energy of Cooper's pairs, and the average in-plane penetration depth. This formula reasonably reproduces empirical values of superconducting transition temperatures for several different cuprate materials near the optimal doping regime, as well as for YBCO films with different doping degrees.