Percolation theory of the pseudogap state

A concept of the pseudogap state in high-T-c layered cuprates on the basis of percolation theory is proposed. Contrary to the self-consistent BCS critical temperature, which defines T*, the upper boundary of the pseudogap state, the real critical temperature T-c is defined as the percolation threshold, where the infinite cluster appears. This permits the exact formula for T-c to be obtained as a function of doping and its "domelike" shape to be understood.