Infinite-layer nickelates as Ni eg Hund’s metals

The recent and exciting discovery of superconductivity in the hole-doped infinite-layer nickelate Nd1-xSrxNiO draws strong attention to unconventional superconductivity. From a theoretical view point, this new class of unconventional superconducting materials provide an opportunity to unveil new physics in correlated quantum materials. Here we study the temperature and doping dependence of the local spectrum of the charge, spin and orbital susceptibilities from first principles. By using ab initio LQSGW+DMFT methodology, we show that onsite Hund's coupling in Ni d orbitals gives rise to multiple signatures of Hund's metallic phase in Ni d subshell. Interestingly, we found that this Hundness is only evident in the Ni eg orbitals and not the Ni t2g orbitals. In this material, the most occupied state (in each subspace with the same total charge) is the one with the maximum Ni eg spin and Ni t2g orbitals are inactive. Our finding unveils a new feature of the Hund’s metals and has potential implications for the broad range of correlated two orbital systems away from half-filling.