The stability of hole-doped antiferromagnetic state in a two-orbital model

Abstract

We investigate the hole-doped antiferromagnetic state in a two-orbital model of cuprates. The model also includes d3z2−r2 orbital. Unlike the one-orbital model, we find the antiferromagnetic state stable against the hole doping for the cuprates with orbital splitting between dx2−y2 and d3z2−r2 orbitals being ∼1 eV. This results from the fact that the Hund’s coupling enforces the filling of dx2−y2 orbital ≈1 indicated by a significant reduction of dx2−y2 spectral density at the Fermi level. This, in turn, leads to the suppression of intraband fluctuations detrimental to the antiferromagnetic phase. In this scenario, hole doping involves removal of mainly d3z2−r2 electrons that are comparatively more localized. One important caveat of our meanfield theoretic result and conclusion is that they are reliable only for a very low hole doping region.