Polycrystalline Sm(Co,Cu)₅ films with perpendicular anisotropy grown on (0 0 0 2) Ru(Cr)

Polycrystalline Sm-Co-Cu films with SmCo₅ phase and (0 0 0 1) texture using a dc magnetron sputtering process were successfully fabricated directly on an (0 0 0 2) Ru(Cr) underlayer on heated glass substrates at 350 °C. The mean grain size of the Sm(CoCu)₅ layer is 17 nm, the smallest ever reported on SmCo₅ film with perpendicular anisotropy. Strong exchange coupling between grains, as indicated by the coercivity squareness, was found in the obtained Sm(Co,Cu)₅ films. An estimated perpendicular magnetic anisotropy constant, as high as 1.4 × 10 ⁸ erg cm^-3, was achieved on these films. An 'unusually' high perpendicular coercivity (11 kOe) was found on these exchange-coupled polycrystalline Sm(Co,Cu)₅ films. This was explained by a pinning-site model which was supported by the measurement of the coercivity angular dependence.