Enhanced Superconductivity Induced by the Hexagonal-Array-Cooling-Shrinkage Effect

Improving the superconductivity of thin films, especially the critical current density (J(C)) and the critical field (H-C), is crucial for the application of superconducting devices. Here, we apply a simple hybrid structure to enhance the superconductivity of Nb films induced by a hexagonal-array-cooling-shrinkage (HACS) effect, which is very sensitive to the temperature and magnetic field. The H-C of the hybrid at 8.8 K is similar to 32% more than that of a flat Nb film, while it is increased to similar to 1000% at 8.97 K. In addition, the HACS effect to enhance superconductivity is more effective than that by uniform compression stress with the same value. The newly proposed approach can be used as self-protection to prevent superconducting devices from losing their superconductivity due to excessive current or magnetic fields.