From Fermi Arcs to the Nodal Metal: Scaling of the Pseudogap with Doping   and Temperature
  The pseudogap phase in the cuprates is a most unusual state of matter: it is a metal, but its Fermi surface is broken up into disconnected segments known as Fermi arcs. Using angle resolved photoemission spectroscopy, we show that the anisotropy of the pseudogap in momentum space and the resulting arcs depend only on the ratio T/T*(x), where T*(x) is the temperature below which the pseudogap first develops at a given hole doping x. In particular, the arcs collapse linearly with T/T* and extrapolate to zero extent as T goes to 0. This suggests that the T = 0 pseudogap state is a nodal liquid, a strange metallic state whose gapless excitations are located only at points in momentum space, just as in a d-wave superconductor. 
A. Kanigel, M. R. Norman, M. Randeria, U. Chatterjee, S. Suoma, A.   Kaminski, H. M. Fretwell, S. Rosenkranz, M. Shi, T. Sat...