  Critical current density (Jc) is one of the major limiting factors for high
field applications of iron-based superconductors. Here, we report that Mn-ions
are successfully incorporated into nontoxic superconducting (Li,Fe)OHFeSe
films. Remarkably, the Jc is significantly enhanced from 0.03 to 0.32 MA/cm^2
under 33 T, and the vortex pinning force density monotonically increases up to
106 GN/m^3, which is the highest record so far among all iron-based
superconductors. Our results demonstrate that Mn incorporation is an effective
method to optimize the performance of (Li,Fe)OHFeSe films, offering a promising
candidate for high-field applications.
