A $d^8$ anti-Hund's Singlet Insulator in an Infinite-layer Nickelate

Abstract

The status of nickelate superconductors in relation to cuprate high temperature superconductors is one of the concepts being discussed in high temperature superconductivity in correlated transition metal oxides. New additions to the class of infinite layer nickelates can provide essential input relating to connections or distinctions. A recently synthesized compound \bnoas, which contains isolated `infinite layer' NiO${}_2$ planes, may lead to new insights. Our investigations have discovered that, at density functional theory mean field level, the ground state consists of an unusual $e_g$ singlet on the Ni${}^{2+}$ ion arising from large but separate Mott insulating gaps in both $e_g$ orbitals, but with different, anti-Hund's, spin directions of their moments. This textured singlet incorporates at the least new physics, and potentially a new platform for nickelate superconductivity, which might be of an unconventional form for transition metal oxides due to the unconventional undoped state. We include in this paper a comparison of electronic structure parameters of Ba${}_2$NiO${}_2$(AgSe)${}_2$ with a better characterized infinite layer nickelate LaNiO${}_2$. We provide more analysis of the $d^8$ anti-Hund's singlet that emerges in this compound, and consider a minimally correlated wavefunction for this singlet in an itinerant background, and begin discussion of excitations -- real or virtual -- that may figure into new electronic phases.

arXiv comment11 pages, 8 figures

References in corpus (22)

• Wannier90: A Tool for Obtaining Maximally-Localised Wannier Functions
• Wien2wannier: From linearized augmented plane waves to maximally localized Wannier functions
• Superconducting Dome in Nd${}_{1-x}$Sr${}_x$NiO${}_2$ Infinite Layer Films
• Phase diagram and superconducting dome of infinite-layer $\mathrm{N}{\mathrm{d}}_{1-\mathrm{x}}\mathrm{S}{\mathrm{r}}_{\mathrm{x}}\mathrm{Ni}{\mathrm{O}}_2$ thin films
• Infinite Layer LaNiO(2): Ni(1+)is not Cu(2+)
• Self-doped Mott insulator for parent compounds of nickelate superconductors
• The critical nature of the Ni spin state in doped NdNiO${}_2$
• Similarities and differences between infinite-layer nickelates and cuprates and implications for superconductivity
• Late transition-metal oxides with infinite-layer structure: Nickelates versus cuprates
• Anisotropy and Magnetism in the LSDA+U Method
• Many-body Electronic Structure of NdNiO${}_2$ and CaCuO${}_2$
• Charge density waves in infinite-layer NdNiO${}_2$ nickelates
• Role of $4f$ states in infinite-layer NdNiO${}_2$
• Influence of apical oxygen on the extent of in-plane exchange interaction in cuprate superconductors
• Lifshitz transition and frustration of magnetic moments in infinite-layer NdNiO${}_2$ upon hole-doping
• Half Semimetallic Antiferromagnetism in the Sr${}_2$CrTO${}_6$ System, T=Os, Ru
• Fluctuation-frustrated flat band instabilities in NdNiO2
• Low Valence Nickelates: Launching the Nickel Age of Superconductivity
• Hund-Heisenberg model in superconducting infinite-layer nickelates
• Designing nickelate superconductors with $d^8$ configuration exploiting mixed-anion strategy
• Proposed ordering of textured spin singlets in a bulk infinite layer nickelate
• Magnetism of competing high-spin/low-spin states in Ba${}_2$NiO${}_2$(AgSe)${}_2$ and related two-orbital two-electron systems

Cited by in corpus (1)

• Softening of $dd$ excitation in the resonant inelastic x-ray scattering spectra as a signature of Hund's coupling in nickelates