Strong anisotropy of cuprate pseudogap correlations: implications for Fermi arcs and Fermi pockets

A full Fermi surface exists in underdoped high-temperature superconductors if the temperature T lies above the pseudogap (PG) temperature T*. Below T* the Fermi surface is anomalous. Some experiments indicate that only arcs of Fermi surface survive. Others indicate that the Fermi surface is closed but consists of pockets with a small surface area. We show that generalizing the Bardeen–Cooper–Schrieffer theory of normal superconductivity to include d-wave pairs and antiferromagnetism on a two-dimensional lattice leads to a T* having a pronounced k dependence because of strong anisotropy in the PG correlations. We discuss implications for gapping of the Fermi surface within the Fermi arc and Fermi pockets picture of underdoped cuprates, and propose that related phenomena arising from anisotropic PG correlations may also occur in underdoped iron arsenide superconductors.