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.