Effective Hamiltonian for superconducting Ni oxides Nd$_{1-x}$Sr$_x$NiO$_2$

Hu Zhang; Lipeng Jin; Shanmin Wang; Bin Xi; Xingqiang Shi; Fei Ye; Jia-Wei Mei

doi:10.1103/PhysRevResearch.2.013214

paper

Effective Hamiltonian for superconducting Ni oxides Nd $_{1 - x}$ Sr $_{x}$ NiO $_{2}$

arXiv:1909.07427 · doi:10.1103/PhysRevResearch.2.013214

Abstract

We derive the effective single-band Hamiltonian in the flat NiO $_{2}$ planes for nickelate compounds Nd $_{1 - x}$ Sr $_{x}$ NiO $_{2}$ . We first 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 $p d σ$ bands of Ni $^{+}$ $3 d_{x^{2} - y^{2}}$ and O $^{2 -}$ $2 p_{x / y}$ orbitals in the NiO $_{2}$ 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 Ni $_{5}$ O $_{16}$ cluster and map the low-energy spectra onto the effective one-band models. We find that the undoped NiO $_{2}$ plane is a Hubbard Mott insulator, and the doped holes primarily locate on Ni sites. The physics of the NiO $_{2}$ plane is a doped Mott insulator, described by the one-band $t$ - $t^{'}$ - $J$ model with $t = 265$ ~meV, $t^{'} = - 21$ ~meV and $J = 28.6$ ~meV. We also discuss the electronic structure for the "self-doping" effect and heavy fermion behavior of electron pockets of Nd $^{3 +}$ $5 d$ character in Nd $_{1 - x}$ Sr $_{x}$ NiO $_{2}$ .

Effective Hamiltonian for superconducting Ni oxides Nd1−x​Srx​NiO2​

Abstract

Effective Hamiltonian for superconducting Ni oxides Nd $_{1 - x}$ Sr $_{x}$ NiO $_{2}$