Superconductivity in thin films of RuN

PHYSICAL REVIEW MATERIALS. 2024. Vol. 8. No. 7. Article 074801.

A.S. Ilin, Strugova A. O., I.A. Cohn, V.V. Pavlovskiy, S.V. Zaitsev-Zotov, Sobolevskiy O., Morgun L., Matrovitskii V. P., Rybalchenko G. V.

Superconductivity has been found in RuN films obtained by reactive magnetron sputtering. This novel member of the metal nitride superconductors family has a critical temperature of the superconducting transition that varies depending on the substrate, ranging from 0.77 K to 1.29 K. The parameters of the crystal lattice of the superconducting films have been determined: The lattice is cubic with rhombohedral distortion along the normal to substrate surface with parameters a = b= c = 4.559 Å for RuN/SiO2, a = b= c = 4.536 Å for RuN/Si, and α = β= γ= 87.96◦ for both films. The upper critical magnetic field at zero temperature Hc2 (0)= 2.3–4.1 T found by extrapolation our experimental data collected at T 0.8 to zero temperature using the WHH model is near the upper paramagnetic limit. An s-wave single-band energy gap of (0)= 0.19 meV was revealed by self-field critical current experiment at temperatures down to 10 mK.

Keywords: Critical temperature, Критическая температура, критический ток, superconductivity, сверхпроводимость, critical current, кристаллическая структура, Crystal structure, critical magnetic field, критическое магнитное поле