  Single crystals of Fe5B2P were grown by self-flux growth technique.
Structural and magnetic properties are studied. The Curie temperature of Fe5B2P
is determined to be 655$pm$2K. The saturation magnetization is determined to be
1.72 MuB/Fe at 2K. The temperature variation of the anisotropy constant K1 is
determined for the first time, reaching ~0.50 MJ/m3 at 2K, and it is comparable
to that of hard ferrites. The saturation magnetization is found to be larger
than the hard ferrites. The first principle calculations of saturation
magnetization and anisotropy constant are found to be consistent with the
experimental results.
