Effective Hamiltonian for nickelate oxides Nd1-xSrxNiO2

Abstract

We derive the effective single-band Hamiltonian in the flat NiO2 planes for nickelate compounds Nd1-xSrxNiO2. We implement the first-principles calculation to study electronic structures of nickelates using the Heyd-Scuseria-Ernzerhof hybrid density functional and derive a three-band Hubbard model for Ni-O pdσ bands of Ni+3dx2-y2 and O2-2px/y orbitals in the NiO2 planes. To obtain the effective one-band t-t′-J model Hamiltonian, we perform the exact diagonalization of the three-band Hubbard model for the Ni5O16 cluster and map the low-energy spectra onto the effective one-band models. We find that the undoped NiO2 plane is a Hubbard Mott insulator and the doped holes are primarily located on Ni sites. The physics of the NiO2 plane is a doped Mott insulator, described by the one-band t-t′-J model with t=265meV, t′=-21meV, and J=28.6meV. We also discuss the electronic structure for the self-doping effect and heavy fermion behavior of electron pockets of Nd3+5d character in Nd1-xSrxNiO2.