Two-dimensional superconductivity in single-band correlated 2H-type NbO2 layers
Takuto Soma, Kohei Yoshimatsu, Koji Horiba, Hiroshi Kumigashira, Akira Ohtomo
DOI 10.1103/PhysRevB.105.104504 · Physical Review B
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Abstract
The oxide superconductor Li1−xNbO2 has two-dimensional (2D) NbO2 layers consisting of edge-shared triangular prisms. This structure is a unique oxide analog to 2H-type transition-metal dichalcogenides (TMDs), yet its electronic properties have not received any significant attention. Using Li1−xNbO2 epitaxial films, we find the 2D superconductivity associated with the Berezinskii-Kosterlitz-Thouless transition and a large anisotropy of the upper critical field. The temperature-independent anisotropy strongly suggests single-band superconductivity, in contrast to TMDs. Correspondingly, the largely isolated single dz2 state revealed by synchrotron-radiation photoelectron spectroscopy and density functional theory is explained in terms of strong ligand field splitting. These results indicate that superconductivity in Li1−xNbO2 occurs in 2D NbO2 layers with a narrow and correlated single band, reminiscent of superconductivity in cuprates. Our study provides insight into the unconventional correlation in the Hubbard system with a 2D triangular lattice.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Li1-xNbO2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 3.5 | Pressure not reported | onset |
| Li1-xNbO2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 4.3 | Pressure not reported | onset |
| Ba3Nb5S Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| KFe2As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| NbSe2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
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