- Este evento ha pasado.
noviembre 22 @ 2:30 pm - 4:00 pm
Ponente: Sanjoy Saker, University of Alabama
Título: Spin-Charge Split paring mechanism for high-Tc superconductors: Experimental Support
Abstract: The metallic phase of a conventional superconductor is a Fermi liquid, characterized by electron quasiparticles, which form Cooper pairs leading to BCS superconductivity. Anderson argued (1987) that high-Tc superconductors are different. In that spin and charge are carried by separate excitations, in these doped Mott insulators. We discuss recent theoretical developments which have shown that a spin-charge separated state emerges if a) the parent (t-J) model is properly renormalized and b) the spin part of the metallic phase is continuously connected to the corresponding state of Mott insulator (undoped). The renormalization also reveals a novel spin-charge split pairing mechanism which is hidden in the parent model. The Cooper pair is replaced by a composite object, chargeless spins are paired into singlets forming a BCS like state, which evolves from the Mott insulator below a temperature T*. Spinless holes, carrying charge +e, are (real-space) paired to form propagating bosons which are gauge coupled to the spin singlets. Superconductivity occurs via Bose-Einstein condensation (BEC) below a temperature Tc < T*. The theory reproduces the observed phases at low doping. In the superconducting state the quantum zero-point energy, through its dependence on the condensate density, accounts for the mysterious T-linear dependence of the observed specific heat, a result that modifies the standard T^3 law associated with Goldstone modes.