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

A superconducting film of (Li-1 Fe-x(x)) OHFeSe is reported for the first time. The thin film exhibits a small in-plane crystal mosaic of 0.22 degrees, in terms of the full width at half maximum of the x-ray rocking curve, and an excellent outof- plane orientation by x-ray phi-scan. Its bulk superconducting transition temperature T-c of 42.4K is characterized by both zero electrical resistance and diamagnetization measurements. The upper critical field H-c2 is estimated to be 79.5T and 443T for the magnetic field perpendicular and parallel to the ab plane, respectively. Moreover, a large critical current density J(c) of a value over 0.5MA/cm(2) is achieved at similar to 20 K. Such a (Li1-xFex) OHFeSe film is therefore not only important to the fundamental research for understanding the high-T-c mechanism, but also promising in the field of high-T-c superconductivity application, especially in high-performance electronic devices and large scientific facilities such as superconducting accelerator.