Vortex structure and Hall conductivity in d-wave superconductors

The Hall conductivity σ_xy serves as an important experimental probe for determining the sign of charge carriers in materials. In type II superconductors models of vortex dynamics predicted σ_xy to have the same sign as in the normal state; that is, the same as the charge carriers. However, Hall measurements showed that σ_xy changes sign as a function of temperature in YBCO and other cuprates, in contradiction to these predictions. Recently it was shown that a sign reversal of σ_xy occurs in a generic model for an s-wave superconductor, due to a topological transition in the vortex core. We show that a similar effect occurs in a model for a d-wave superconductor, and find a rich phase diagram of σ_xy as a function of interaction strength and doping p: in addition to a sign reversed phase, we find a phase in which σ_xy ∼ p . While such a relation implies a small Fermi surface, the model does not exhibit a bulk Fermi surface reconstruction.