Electronic Properties, Band Structure, and Fermi Surface Instabilities of Ni1+/Ni2+ Nickelate La3Ni2O6, Isoelectronic with Superconducting Cuprates

Electronic structure calculations were performed for the mixed-valent Ni1+/Ni2+ nickelate La3Ni2O6, which exhibits electronic instabilities of the Fermi surface similar to that of the isostructural superconducting La2CaCu2O6 cuprate. La3Ni2O6 shows activated hopping, which fits to Mott's variable-range-hopping model with localized states near the Fermi level. However, a simple local spin density approximation calculation leads to a metallic ground state. The calculations including local density approximation+Hubbard U and hybrid functionals indicate a multiply degenerate magnetic ground state. For electron-doped La2ZrNi2O6, which is isoelectronic with La2CaCu2O6, an antiferromagnetic insulating ground state is found when correlations are included. The nickelates are thus ideal model systems for a deeper understanding of correlated transition metal compounds, magnetism, and superconductivity.