Localized High-Tc Superconductivity on the Surface of Na-Doped WO3
- Cite this article as:
- Reich, S., Leitus, G., Tssaba, Y. et al. Journal of Superconductivity (2000) 13: 855. doi:10.1023/A:1007867710512
WO3 crystals were doped with Na on the surface to ∼7% nominal atomic concentration. Scanning tunneling microscopy and spectroscopy were employed, together with magnetization measurements, in the study of these crystals. Tunneling experiments reveal superconducting islands, 20–150 nm in size, covering about 10% of the surface, the rest of which is insulating. Magnetization measurements show that the superconducting phase formed at the surface has a critical temperature of 91 K, while tunneling spectroscopy yields superconducting gaps having values up to 2Δ/kTc ∼ 4. Presumably most of the sodium is concentrated in these islands and therefore they are metallic in nature, above 30% in atomic concentration. This material is therefore a noncuprate superconductor with a high critical temperature.