“…The SmCo 5 alloy, a representative permanent magnet material, is a promising candidate for the materials because of its extremely high uniaxial magnetocrystalline anisotropy, whose K u value is 1.1×10 8 erg/cm 3 or greater in the form of bulk alloy [34]. However, an SmCo 5 thin film exhibiting distinct perpendicular magnetic anisotropy had not been prepared, although the film with in-plane anisotropy is relatively easy to prepare, for instance, by using a Cr underlayer [35][36][37][38][39]. Recently, we succeeded in developing sputter-deposited SmCo 5 thin films with very high perpendicular magnetic anisotropy [40][41][42][43][44][45]; it will be stated in detail in this section.…”