Flat Ferromagnetic, Epitaxial 48Ni/52Fe(111) Films of few Atomic Layers

Flat epitaxial 48Ni/52Fe(111) films are prepared by evaporation onto atomically flat Cu(111) films. All films consisting of three or more layers (d ≧ 6 Å) show a far‐reaching fit to the model structure of a flat single crystal. The magnetic properties are determined for (70 ≦ T ≦ 400) °K with an oscillation type torsion magnetometer, which can detect a moment of 5 × 10 −8 G cm 3 . All films of three or more layers are ferromagnetic without any indication of superparamagnetism; Curie‐temperature and magnetization decrease monotonously with film thickness; there is good qualitative agreement with spin‐wave theory and Green's function theory; the magnetization is independent of the field, however, within 1%, for (300 ≦ H ≦ 5000) Oe, while the theory predicts considerable dependence on the field. Strong anisotropies relating to the surface normal as easy axis may easily be interpreted as Néel‐type surface anisotropies.