Superconductivity from pseudogap through attraction between spin-vortices

Within the framework of the spin–charge gauge approach to the 2D t–J model (Marchetti et al., 2007 [1]) we propose a new non-BCS mechanism for superconductivity in hole-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 finite doping concentration, when both the 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.