Abstract

The spin-charge gauge approach to the two-dimensional t-J model to consider the metal-insulator crossover and other anomalous transport properties in High-Tc cuprates is first briefly reviewed. Within this framework we propose a new non-BCS mechanism for superconductivity in underdoped cuprates. The gluing force is an attraction between spin vortices centered at the empty sites (described by fermionic holons) in two different Néel sublattices. This attraction induces in turn, through a gauge interaction originated from the no-double occupation constraint, formation of Resonance Valent Bond (RVB) spin pairs (described in terms of bosonic spinons). When holon pairs condense, a finite density of RVB spinon pairs appears. Superconductivity occurs at T=0 at a finite doping concentration, when both holon- vortex pairs and the RVB spinon pairs are condensed. Its precursor is a normal state region where magnetic vortices proliferate, leading to superconductivity via a 3D gauged-XY transition.

References:

[1] P.A. Marchetti, Z.B. Su, L.Yu, J. Phys. Condens. Matter 19, 125209 (2007) and references therein

[2] P.A. Marchetti, F. Ye, Z.B. Su, L.Yu, Proceedings of the 2009 M2S Conference, September 2009, Tokyo.