The Critical Temperature of Cuprate and Organic Superconductors

At present, there is no complete theory of superconductivity, which entails the need to solve a number of important research problems. In particular, is no expression capable of describing the critical temperature of all superconducting materials. Superconductors in the transition from their superconducting to normal state are considered. To this end, an analogy between the plasmons in metal and oscillations of superconducting electrons is taken, based of which expressions for the critical temperature and superconducting particle velocity as functions of coherence length and London penetration depth are obtained. The obtained dependences show that the critical temperature increases with increasing the coherence length and decreases with increasing the London penetration depth. The possible coherence length and London penetration depth values for possible room-temperature superconductors are given. The theoretical values of the superconductor critical temperature are in good agreement with the experimentally measured values for organic and cuprate superconductors. Based on the obtained expression for the critical temperature, a generalization of the expression for some alloys, metal compounds, Chevrel phases, and iron pnictides is proposed.