We have fabricated artificial grain boundaries in K-doped BaFe2As2 (Ba122:K), one of the Fe-based superconductors. The crystalline orientation map, acquired through the scanning precession electron diffraction measurements, revealed that spontaneous connectivity modification occurred at the grain boundary, which may mitigate weak-link behavior. Specifically, a self-field critical current density Jc of over 0.1 MA/cm2 across the grain boundary with misorientation angles up to 24° was recorded even at 28 K. This performance surpasses the grain boundary properties of hitherto reported Fe-based superconductors. Our results highlight the exceptional potential of Ba122:K for polycrystalline applications and pave the way for next-generation superconducting magnets.
- Takafumi Hatano
- Dongyi Qin
- Akiyasu Yamamoto
