Radiation effects in higherature YBa₂Cu₃O_7-x superconducting thin films with low-energy protons for space radiation environments

This paper presents the irradiation effects and microstructure evolution in YBa₂Cu₃O_7-x (YBCO) thin films irradiated with low-energy protons. The microstructure changes can arise from atomic displacements characterized by micro-Raman spectroscopy. Providing different fluence low-proton irradiation conditions to simulate the space proton environment, the obvious properties change of the transition temperature T _c and critical current density J _c can be observed. In accordance with micro-Raman spectroscopy observations, the main components of proton-radiation-induced defects are that displacements of oxygen atoms in Cu-O chains. These oxygen defects acting as effective pinning centers for flux vortices increase the pinning force F _p and the critical current density J _c. However, a further healing process of broken Cu-O chains occurs with further proton irradiation, which leads to a weaker pinning force F _p and a decreased critical current density J _c. This work provides the damage profiles of the proton radiation on higherature YBCO superconducting thin films, which are extraordinarily important for the future superconductor applications in long-time space missions.