Vortex matching effects and flux dynamics manipulation in MgB₂ thin films via He-FIB-induced periodic artificial pinning centers

Flux dynamics, which describes the behavior of magnetic vortices in type-II superconductors, governs macroscopic electromagnetic properties of superconducting materials. Recently, cutting-edge approaches utilizing artificial periodic nanostructures for active control of the pinning centers help to deepen the understanding of relevant mechanisms of flux dynamics. This study demonstrates the controlled introduction of large-scale, periodic artificial pinning centers (APCs) in MgB₂ superconducting thin films to manipulate flux dynamics. Using focused helium ion beam (He-FIB) irradiation, we fabricated a square array of nanoscale columnar artificial pinning centers with a period of 100 nm on a 30 nm MgB₂ superconducting thin film. Magnetoresistance measurements near the critical temperature (T_c) reveal a pronounced vortex matching effect, evidenced by sharp resistance minima (dips) at specific integer and fractional magnetic matching fields. This effect is shown to be highly dependent on external parameters such as temperature, driving current, and the angle of the magnetic field. Furthermore, the large-area irradiation systematically suppresses T_c and broadens the superconducting transition of the film. This work establishes He-FIB as a potent tool for advanced flux pinning engineering and provides a comprehensive understanding of flux dynamics in superconductors with periodic pinning landscapes.