Vortex structure in underdoped cuprates

In underdoped cuprates the normal state is highly anomalous and is characterized as a pseudogap phase. The question of how to describe the “normal” core of a superconducting vortex is an outstanding open problem. We show that the SU(2) formulation of the t-J model provides a description of the normal state as well as the vortex core. Interestingly, the pseudogap persists inside the core. We also found that it is likely that the core consists of a state that breaks translational symmetry due to the existence of a staggered current that generates a staggered magnetic field with very slow dynamics. This staggered-flux state is likely to be the ground state for magnetic fields higher than H_c2. Experiments to test this picture are proposed.