Distinguishing pseudogap models

Understanding and describing the pseudogap state in the cuprate superconductors continues to be a major unsolved problem. There are several physically distinct models for this state of matter (fluctuating d-wave superconductor, density wave state, nodal metal, ...). A key problem to explain are the "arcs" seen in ARPES experiments. A nice comparison of the different models has been given by Mike Norman and collaborators in this PRB paper.

Mike Smith and I have just finished a paper where we consider the charge and thermal transport of the different pseudogap models. One thing we encountered was that defining the charge current operator is a rather confusing and ambiguous problem. This has significant effects on the results, particularly the doping and disorder dependence of the conductivity and Lorenz ratio. Consequently, it may be possible to rule out some of the models using transport measurements.