Superconducting Phase Transitions and Flux Pinning Configurations in Niobium-Nitride Nanowire Networks

International Journal of Physics | Vol. 9, No. 9, September 2018 | pp. 65–72

DOI: 10.46882/2018/IJP/000101

Research Article

Title: Superconducting Phase Transitions and Flux Pinning Configurations in Niobium-Nitride Nanowire Networks

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

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

Abstract: Enhancing the current-carrying capability of superconducting arrays under strong magnetic fields is a critical requirement for single-photon detectors and quantum information circuits. This study evaluates the superconducting phase transitions and maps magnetic flux pinning configurations in niobium-nitride (NbN) interconnected nanowire networks. The networks were prepared via electro-beam lithography and reactive ion etching on sapphire substrates with wire widths ranging from 20.0 nm to 100.0 nm. We conducted low-temperature electrical transport and magnetometry measurements across a temperature range of 1.5 K to 15.0 K under magnetic fields up to 10.0 T. The pristine 100.0 nm network displayed a sharp superconducting transition with a critical temperature (Tc) of 15.2 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 the geometric network boundaries induce a strong vortex-matching effect, enhancing stability. The upper critical field, Hc2(0), was estimated to be 24.5 T by applying the Werthamer-Helfand-Hohenberg theoretical model. These findings demonstrate that nanoscale patterning significantly improves flux lattice stability, offering structural strategies for device engineering.

Keywords: Superconductivity; nanowires; flux pinning; critical current density; upper critical field; quantum circuits

Manuscript Timeline: Received: May 14, 2018; Revised: July 08, 2018; Accepted: August 03, 2018; Published: September 11, 2018

Citation: Semenov, O. K., & Kim, Y. S. (2018). Superconducting Phase Transitions and Flux Pinning Configurations in Niobium-Nitride Nanowire Networks. International Journal of Physics, 9(9), 65–72.

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