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 ${d}_{3{z}^{2}-{r}^{2}}$ orbital. Unlike the one-orbital model, we find the antiferromagnetic state stable against the hole doping for the cuprates with orbital splitting between ${d}_{{x}^{2}-{y}^{2}}$ and ${d}_{3{z}^{2}-{r}^{2}}$ orbitals being ∼1 eV. This results from the fact that the Hund’s coupling enforces the filling of ${d}_{{x}^{2}-{y}^{2}}$ orbital ≈1 indicated by a significant reduction of ${d}_{{x}^{2}-{y}^{2}}$ 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 ${d}_{3{z}^{2}-{r}^{2}}$ 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.

Keywords

• cuprates
• Hund's coupling
• spin-wave excitations
• antiferromagnetic state