Superconducting （Li,Fe）OHFeSe Film of High Quality and High Critical Parameters

A superconducting film of （Li1-xFex）OHFeSe is reported for the first time. The thin film exhibits a small in-plane crystal mosaic of 0.22°, in terms of the full width at half maximum of the x-ray rocking curve, and an excellent out-of-plane orientation by x-ray φ-scan. Its bulk superconducting transition temperature Tc of 42.4 K is characterized by both zero electrical resistance and diamagnetization measurements. The upper critical field Hc2 is estimated to be 79.5 T and 443 T for the magnetic field perpendicular and parallel to the ab plane, respectively. Moreover, a large critical current density Jc of a value over 0.5 MA/cm2 is achieved at-20 K. Such a （Li1-xFex）OHFeSe film is therefore not only important to the fundamental research for understanding the high-Tc mechanism, but also promising in the field of high-To superconductivity application, especially in high-performance electronic devices and large scientific facilities such as superconducting accelerator.