Two-band model for magnetism and superconductivity in nickelates

Lun-Hui Hu; Congjun Wu

doi:10.1103/PhysRevResearch.1.032046

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Two-band model for magnetism and superconductivity in nickelates

Lun-Hui Hu, Congjun Wu

DOI 10.1103/PhysRevResearch.1.032046 · Physical Review Research

T1

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Abstract

The recently discovered superconductivity in Nd1−xSrxNiO2 provides a new opportunity for studying strongly correlated unconventional superconductivity. The single-hole Ni+ (3d9) configuration in the parent compound NdNiO2 is similar to that of Cu2+ in cuprates. We suggest that after doping, the intraorbital spin-singlet and interorbital spin-triplet double-hole (doublon) configurations of Ni2+ are competing, and we construct a two-band Hubbard model by including both the 3dx2−y2 and 3dxy orbitals. The effective spin-orbital superexchange model in the undoped case is a variant of the SU(4) Kugel-Khomskii model augmented by symmetry-breaking terms. Upon doping, the effective exchange interactions between spin-12 single holes, spin-1 (triplet) doublons, and singlet doublons are derived. Possible superconducting pairing symmetries are classified in accordance to the D4h crystalline symmetry, and their connections to the superexchange interactions are analyzed.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Nd0.8Sr0.2NiO2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	9	Pressure not reported	onset
Nd0.8Sr0.2NiO2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	15	Pressure not reported	onset