TOWARD A UNIFIED MAGNETIC PHASE-DIAGRAM OF THE CUPRATE SUPERCONDUCTORS

We propose a unified magnetic phase diagram of the cuprate superconduc tors. A new feature of this phase diagram is a broad intermediate dopi ng region of quantum-critical, z = 1, behavior, characterized by tempe rature independent T1T/T2G and linear TiT, where the high energy spin waves are not overdamped. The spin gap in the moderately doped materia ls is related to the suppression of the spectral weight for frequencie s smaller than DELTA(xi)=c/xi in the quantum disordered, z = 1, regime . The crossover to the z = 2 regime, where TiT/T2G2 is similar to cons t, occurs only in the fully doped materials.