Possible Universal Cause of High-T_c Superconductivity in Different Metals

Using the theory of the high temperature superconductivity based on the idea of the fermion condensation quantum phase transition (FCQPT), we show that neither the d-wave pairing symmetry, nor the pseudogap phenomenon, nor the presence of the Cu-O_2 planes are of decisive importance for the existence of the high-T_c superconductivity. We analyze recent experimental data on this type of superconductivity in different materials and show that these facts can be understood within the theory of superconductivity based on FCQPT. The latter can be considered as a universal cause of the high-T_c superconductivity. The main features of a room-temperature superconductor are discussed.