Synthesis of Thin Niobium Films on Silicon and Study of Their Superconducting Properties in the Dimensional Crossover Region

• Published in: Technical physics Vol. 66; no. 2; pp. 263 - 268
• Main Authors: Yanilkin, I. V., Gumarov, A. I., Rogov, A. M., Yusupov, R. V., Tagirov, L. R.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.02.2021; Springer; Springer Nature B.V
• Subjects: Classical and Continuum Physics; Conduction electrons; Dielectric films; Magnetic fields; Magnetism; Niobium; Physics; Physics and Astronomy; Silicon; Silicon substrates; Solid State; Superconductivity; Superconductors; Synthesis; Temperature; Thickness; Thin films; Transition temperature; Ultrahigh vacuum
• ISSN: 1063-7842; 1090-6525
• DOI: 10.1134/S1063784221020249

Niobium films with a thickness of 4–100 nm are synthesized on a silicon substrate under ultrahigh vacuum conditions. Measurements of the electrical resistance show a high superconducting transition temperature T c in the range of 4.7–9.1 K and record-breaking small transition widths Δ T c in the range of 260–11 m. The dependences of T c and Δ T c on the magnetic field are investigated, and the superconducting coherence lengths and mean free paths of conduction electrons for different thicknesses of the synthesized films are determined. A significant influence of the magnetic field on Δ T c is found, which reveals the transition from three- to two-dimensional superconductivity at thicknesses below 10 nm. The dependences of T c and Δ T c on the thickness of the films and the magnitude of the magnetic field are discussed within the framework of existing theories of superconductivity in thin films of superconducting metals.