Enhanced perpendicular magnetic properties of Pr-Fe-B thin films by segregating Cu element at grain boundaries

In this study, we investigated the microstructural and magnetic properties of Pr-Fe-B thin films doped with elemental Cu. The thin coercivity (Hc) of the film was about 200 kA/m in the absence of Cu but increased to about 320 kA/m after adding 8.5-15.3 at.% Cu. A further increase in Cu content led to a decrease in Hc and squareness (S). While adding a small amount of Cu could create pinning sites in the Pr-Fe-B matrix to enhance coercivity, excess Cu addition inhibited the formation of a hard magnetic phase. In this paper, Cu-rich segregation, Pr-rich grain boundaries, de-coupled Pr-Fe-B grains, and exchange coupling between soft and hard phases were the mechanisms used to enhance the magnetic properties of Pr-Fe-B films with Cu. We demonstrated that Pr-Fe-B-Cu thin films containing a suitable amount of Cu are helpful in preparing perpendicular magnetic anisotropic Pr-Fe-B-Cu films.