TOWARD A UNIFIED MAGNETIC PHASE-DIAGRAM OF THE CUPRATE SUPERCONDUCTORS

We propose a unified magnetic phase diagram of the cuprate superconductors. A new feature of this phase diagram is a broad intermediate doping region of quantum-critical, z = 1, behavior, characterized by temperature independent T1T/T2G and linear TiT, where the high energy spin waves are not overdamped. The spin gap in the moderately doped materials is related to the suppression of the spectral weight for frequencies 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 const, occurs only in the fully doped materials.