Emergent Resistive Regimes in Granular Superconductors: A TDGL Study of Vortex Dynamics and Engineered Defects
Talles Benites1, Alice Presotto1, Adriana Guiráo Presotto1, J Barba-Ortega2, André Luiz Malvezzi3, Edson Sardella3, Elwis Carlos Sartorelli Duarte4, Rodolfo Izquierdo1 and Rafael Zadorosny1
1 Departamento de Física e Química, Faculdade de Engenharia, Universidade Estadual Paulista (UNESP), Ilha Solteira-SP, Brazil
2 Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia
3 Departamento de Física, Faculdade de Ciências, Universidade Estadual Paulista (UNESP), Bauru-SP, Brazil
4 Universidade Estadual de Maringá (UEM), Câmpus Regional de Goioerê, Goioerê-PR, Brazil
Abstract
In type-II superconductors, the interaction between transport currents and magnetic vortices governs the transition from dissipationless to resistive states. This transition is driven by the competition between the Lorentz force acting on vortices and the pinning forces associated with material inhomogeneities. In this study, we explore the impact of engineered microstructural features on vortex behavior in granular superconductors. The system is modeled as a superconducting tape composed of grains connected by weak links, characterized by locally reduced critical temperatures, and incorporating controlled intra-grain defect distributions. The analysis is conducted through numerical simulations based on the generalized time-dependent Ginzburg–Landau (TDGL) framework, considering different magnetic field intensities and transport current regimes. The results indicate that, although intra-grain defects do not significantly enhance vortex pinning, they play a crucial role in modulating vortex trajectories and slowing their dynamics. This effect contributes to a shift in the onset of dissipation and leads to complex resistive responses. At low magnetic fields, interactions between vortices located within grains and those at grain boundaries promote collective effects, including the emergence of negative differential resistance. Additionally, the dependence of the critical current on the applied magnetic field exhibits oscillatory features reminiscent of Fraunhofer patterns, highlighting the Josephson-like nature of the weak links. These findings provide insights into the design of granular superconducting systems, particularly for applications in sensing technologies and quantum devices.
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