Infinite-layer nickelates as Ni-eg Hund's metals

The recent and exciting discovery of superconductivity in the hole-doped infinite-layer nickelate Nd1-& delta;Sr & delta;NiO2 draws strong attention to correlated quantum materials. From a theoretical view point, this class of unconventional superconducting materials provides an opportunity to unveil a physics hidden in correlated quantum materials. Here we study the temperature and doping dependence of the local spectrum as well as 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-e(g) orbitals. The proposed picture of the nickelates as an e(g) (two orbital) Hund's metal differs from the picture of the Fe-based superconductors as a five orbital Hund's metal as well as the picture of the cuprates as doped charge transfer insulators. Our finding uncover a new class of the Hund's metals and has potential implications for the broad range of correlated two orbital systems away from half-filling.

Automated summary

The recent discovery of superconductivity in Nd1-δSrδNiO2 has attracted strong attention to correlated quantum materials. From a theoretical perspective, this provides an opportunity to uncover hidden physics in such unconventional superconducting materials. Through first principles calculations, we investigate the temperature and doping dependence of the local spectrum and various susceptibilities, revealing the presence of a Hund's metallic phase in the Ni-e(g) orbitals induced by the onsite Hund's coupling in Ni-d orbitals. Our findings suggest a new class of Hund's metals with potential implications for correlated two orbital systems away from half-filling.