Phase diagram of high-temperature superconducting cuprates and pnictides

Phase diagram of high-temperature superconducting cuprates and iron pnictides is considered based on the theory emphasizing that the electronic state of superconductors can be described by the composed fermions. The theory is constructed with the Hamiltonian so modified by the unitary transformation as to apply the mean field approximation. It is indicated that the phase diagram of these superconductors can be explained from the viewpoint unifying the electronic states of superconducting cuprates and pnictides. The issues relevant to exotic phases are also discussed.