Publication details
Superconductivity in the spin-state crossover materials: Nickelates with planar-coordinated low-spin Ni2+ ions
| Authors | |
|---|---|
| Year of publication | 2025 |
| Type | Article in Periodical |
| Magazine / Source | Physical Review B |
| MU Faculty or unit | |
| Citation | |
| web | https://journals.aps.org/prb/abstract/10.1103/s5b6-crzc |
| Doi | https://doi.org/10.1103/s5b6-crzc |
| Keywords | Exchange interaction; Magnetic interactions; Magnetism; Spin dynamics; Spin fluctuations; High-temperature superconductors; Mott insulators; Approximation methods for many-body systems; Exact solutions for many-body systems |
| Description | We theoretically study quasi-two-dimensional nickel compounds, where the nickel ions assume Ni2+??8 valence state and feature a low-spin ??=0 ground state quasidegenerate with ??=1 ionic excitations. Such a level structure is supported by square-planar coordination of nickel ions or a suitable substitution of apical oxygens. We construct the corresponding singlet-triplet exchange model and explore its phase diagram and excitation spectrum. By hole doping, we further introduce mobile Ni3+??7 ionic configurations with effective spins ??=1/2, and analyze their interactions with the ??8 singlet-triplet background. The interplay with the triplet excitations in the ??8 sector is found to have a deep impact on the propagation of the doped holelike charge carriers and is identified as a powerful source of Cooper pairing among them. |
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