Metal–insulator transition in layered cuprates (SDW model)

Abstract

The metal–insulator transition in layered cuprates is analyzed on the basis of the assumption that it is due to formation of a spin-density wave ( Section 2). The phase diagram in the plane of temperature and doping is calculated ( Section 3); doping is described by the chemical potential. The phase transition from the insulating antiferromagnetic phase to a metallic paramagnetic phase proves to be a second order transition at small dopings and a first order transition at larger ones. The connection between the chemical potential and measurable physical properties is analyzed ( Section 4). In the metallic phase it defines the volume, enclosed in the Fermi surface, which is always large. In the insulating phase it defines the energy gap. Next, the role of disorder is studied ( Section 5). It is shown that disorder reduces the antiferromagnetic region at the phase diagram but qualitatively does not change the nature of the transitions, namely second order at smaller dopings and first order at larger ones.