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

International Journal of Physics | Vol. 11, No. 8, August 2020 | pp. 57–64

DOI: 10.46882/2020/IJP/000124

Research Article

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

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

Authors’ Affiliations:
¹ Institute for Solid State Physics, Russian Academy of Sciences, Moscow, Russia
² Department 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 superconducting quantum circuits and highly sensitive photon detectors. This study evaluates the superconducting phase transitions and maps magnetic flux pinning mechanisms in titanium-nitride (TiN) 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 1.5 K to 10.0 K under magnetic fields up to 6.0 T. The pristine 300.0 nm film displayed a sharp superconducting transition with a critical temperature (Tc) of 5.2 K at zero field. Magnetization loops revealed a high critical current density (Jc) exceeding 1.8 x 10^6 A/cm² at 2.0 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 7.4 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 device optimizations.

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

Manuscript Timeline: Received: April 05, 2020; Revised: June 01, 2020; Accepted: June 28, 2020; Published: August 14, 2020

Citation: Semenov, O. K., & Santos, D. L. (2020). Superconducting Phase Transitions and Magnetic Flux Pinning Mechanisms in Titanium-Nitride Thin Films. International Journal of Physics, 11(8), 57–64.

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