Influence of carbon-ion irradiation on the superconducting critical properties of MgB₂ thin films

Abstract

We investigate the influence of carbon-ion irradiation on the superconducting critical properties of MgB 2 thin films. MgB 2 films of two thicknesses viz. 400 nm (MB400nm) and 800 nm (MB800nm) were irradiated by 350 keV C ions having a wide range of fluence, 1  10 13 -1  10 15 C atoms/cm 2 . The mean projected range (R p ) of 350 keV C ions in MgB 2 is 560 nm, thus the energetic C ions will pass through the MB400nm, whereas the ions will remain into the MB800nm. The superconducting transition temperature (T c ), upper critical field (H c2 ), c-axis lattice parameter, and corrected residual resistivity (ρ corr ) of both the films showed similar trends with the variation of fluence. However, a disparate behavior in the superconducting phase transition was observed in the MB800nm when the fluence was larger than 110 14 C atoms/cm 2 because of the different T c s between the irradiated and non-irradiated parts of the film.Interestingly, the superconducting critical properties, such as T c , H c2 , and J c , of the irradiated MgB 2 films, as well as the lattice parameter, were almost restored to those in the pristine state after a thermal annealing procedure. These results demonstrate that the atomic lattice distortion induced by C-ion irradiation is the main reason for the change in the superconducting properties of MgB 2 films.

High critical current density and high-tolerance superconductivity in high-entropy alloy thin films

“…4 ). Although the magnitude of the applied magnetic field increased, the SC transition of the HEA SC thin films did not broaden considerably, revealing that the HEA superconductor has a strong vortex pinning strength 17 , 18 . In general, because the number of vortices is proportional to the magnetic field and the vortex motion generates an electric field, an increase in the magnetic field results in a broad SC transition in type-II superconductors with weak vortex pinning strengths 19 , 20 .…”

Influence of disorder strength on the superconducting mechanism of MgB2

“…The (002) peak position of the MgB 2 gradually shifts to a lower angle with an increase in the dose level. A change in lattice constant of various crystalline materials, such as MgB 2 , Nb 3 Sn, and YBa 2 Cu 3 O x , has been widely reported due to ion irradiation [26][27][28]. In addition, a primary disorder in MgB 2 thin films produced by low energy ion irradiations has been reported as lattice displacements together with point defects, such as interstitials and vacancies [29,30].…”

Maximum reduction of energy losses in multicore MgB2 wires by metastructured soft-ferromagnetic coatings

“…Now, there are multiple pathways to be considered when optimizing SC multifilamentary wires. On the one hand, there are extrinsic techniques like chemical doping 66 – 68 or irradiation treatments 69 – 71 , which both can enhance the by improving the flux pinning mechanism, but do not change that the AC-losses will still be dominated by the contributions of the SC filaments and its metallic matrix. On the other hand, extrinsic methods such as the twisting of the filaments can lower the AC-losses, but at the expense of an undesired reduction of 58 .…”