Generic source of perpendicular anisotropy in amorphous rare-earth transition-metal films

We show that the magnetic dipolar energy of antiparallel dipoles in the surface layers contributes to the intrinsic perpendicular anisotropy in amorphous rare-earth transition-metal films. The volume anisotropy energy density Ku of this contribution depends inversely on the thickness of the film. For an amorphous GdCo film with a thickness of 1000 the calculated Ku is on the order of 103 104 ergs cm3. Dependence of Ku on temperature and atomic concentration is also calculated.