Superconducting Phase Transitions and Magnetic Flux Dynamics in Niobium-Carbon Thin Films

International Journal of Physics | Vol. 15, No. 6, June 2024 | pp. 41–48

DOI: 10.46882/2024/IJP/000170

Research Article

Title: Superconducting Phase Transitions and Magnetic Flux Dynamics in Niobium-Carbon Thin Films

Names of Authors: O. K. Semenov¹, Y. S. Kim²

Authors’ Affiliations:
¹ Institute for Solid State Physics, Russian Academy of Sciences, Moscow, Russia
² Department of Physics and Astronomy, Seoul National University, Seoul, South Korea

Abstract: Stabilizing the magnetic vortex lattice and maximizing the critical current capacity of superconducting layers under strong applied magnetic fields are vital for engineering single-photon sensors and high-field laboratory magnets. This study evaluates the superconducting phase transitions and maps magnetic flux pinning configurations in niobium-carbon (Nb-C) thin films. The thin films were prepared via magnetron sputtering on sapphire substrates with thickness parameters ranging from 50.0 nm to 300.0 nm. We conducted low-temperature electrical transport and magnetometry profiles across a temperature grid from 1.5 K to 15.0 K under magnetic fields up to 10.0 T. The pristine 300.0 nm film displayed a sharp superconducting transition with a critical temperature (Tc) of 11.2 K at zero field. Magnetization loops revealed a high critical current density (Jc) exceeding 4.2 x 10^6 A/cm² at 4.2 K. Analysis of the pinning force density indicates that introducing nanoscale carbon inclusions triggers an intensive vortex-locking matching effect. The upper critical field, Hc2(0), was estimated to be 14.5 T using the Werthamer-Helfand-Hohenberg model, proving that grain boundary control improves layer performance.

Keywords: Superconductivity; thin films; flux pinning; critical current density; upper critical field; magnetron sputtering

Manuscript Timeline: Received: March 02, 2024; Revised: April 14, 2024; Accepted: May 02, 2024; Published: June 18, 2024

Citation: Semenov, O. K., & Kim, Y. S. (2024). Superconducting Phase Transitions and Magnetic Flux Dynamics in Niobium-Carbon Thin Films. International Journal of Physics, 15(6), 41–48.

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