Superconducting Phase Transitions and Magnetic Flux Pinning Mechanisms in Vanadium-Nitride Thin Films

International Journal of Physics | Vol. 7, No. 10, October 2016 | pp. 73–80

DOI: 10.46882/2016/IJP/000078

Research Article

Title: Superconducting Phase Transitions and Magnetic Flux Pinning Mechanisms in Vanadium-Nitride Thin Films

Names of Authors: O. K. Semenov¹, D. L. Santos²

Authors’ Affiliations: ¹Institute for Solid State Physics, Russian Academy of Sciences, Moscow, Russia; ²Department of Physics, University of Coimbra, Coimbra, Portugal

Abstract: Enhancing the current-carrying capability of superconductors under strong magnetic fields is a critical requirement for next-generation particle accelerators and magnetic resonance imaging systems. This study evaluates the superconducting phase transitions and maps magnetic flux pinning mechanisms in vanadium-nitride (VN) thin films. The thin films were prepared via magnetron sputtering on sapphire substrates with film thicknesses ranging from 50.0 nm to 300.0 nm. We conducted low-temperature electrical transport and magnetometry measurements across a temperature range of 2.0 K to 15.0 K under magnetic fields up to 8.0 T. The pristine 300.0 nm film displayed a sharp superconducting transition with a critical temperature (Tc) of 8.6 K at zero field. Magnetization loops revealed a high critical current density (Jc) exceeding 2.8 x 10^6 A/cm² at 4.2 K. Analysis of the pinning force density indicates that the dominant pinning mechanism shifts from core-surface pinning to point-defect pinning as the temperature approaches Tc. The upper critical field, Hc2(0), was estimated to be 10.5 T by applying the Werthamer-Helfand-Hohenberg theoretical model. These findings demonstrate that nanoscale grain boundary control significantly improves vortex lattice stability, offering structural strategies for high-field superconducting applications.

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

Manuscript Timeline: Received: June 02, 2016; Revised: July 29, 2016; Accepted: August 25, 2016; Published: October 08, 2016

Citation: Semenov, O. K., & Santos, D. L. (2016). Superconducting Phase Transitions and Magnetic Flux Pinning Mechanisms in Vanadium-Nitride Thin Films. International Journal of Physics, 7(10), 73–80.

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