The Stripe-Phase Quantum-Critical-Point Scenario for Hight- T c Superconductors

A summary is given of the main outcomes of the quantum-critical-point scenario for high-Tc superconductors, developed in the last few years by the Rome group. Phase separation, which commonly occurs in strongly correlated electronic systems, turns into a stripe instability when Coulomb interaction is taken into account. The stripe phase continuously connects the high-doping regime, dominated by charge degrees of freedom to the low-doping regime, where spin degrees of freedom are most relevant. Dynamical stripe fluctuations enslave antiferromagnetic fluctuations at high doping. Critical fluctuations near the stripe instability mediate a singular interaction between quasi-particles, which is responsible for the non-Fermi liquid behavior in the metallic phase and for the Cooper pairing with d-wave symmetry in the superconducting phase.