ORIGIN OF THE GIANT PERPENDICULAR MAGNETIC ANISOTROPY OF “AMORPHOUS” Tb-Gd-Fe THIN FILMS

Abstract

  Microstructure and the electronic property of amorphous (Tb_0.5Gd_0.5)_X Fe_100-X (X= 10∼30) films with a giant perpendicular magnetic anisotropy (GPMA, the uniaxial anisotropy constant K_u =∼10⁷ erg/em³) have been studied in detail. As a result it is found that these films consist of large “crystals” of which the local atomic arrangement is similar to GdFe₅ (CaCu₅-type, hexagonal) and their c-axes orient in the normal direction to the film plane. Therefore, the GPMA is considered to be generated from the “crystalline” phase. Considering the large electrical resistivity of these films, perpendicular anisotropy is probably induced by the random pair formation of neighboring rare earth (RE=Tb,Gd) atoms in the <001> direction of the REFe₅ structure.