The magnetoresistivity, structure, and magnetic anisotropy of RF sputtered and E-beam evaporated NiFe films

Abstract

Magnetoresistivity, magnetic hysteresis loop, and structure were studied on both RF sputtered (S-films) and E-beam evaporated (E-films) Ni81Fe19 films (4700 Å thick). The E-films were deposited on a rotating substrate (∼385 °C). The S-films were prepared on a stationary substrate with heat sinking. The room temperature magnetoresistivity (ΔR/R) were about 4.0% for E-films and about 3.7% for S-films. The ΔR/R differences for these two films resulted from higher resistivity of S-films. The structure of these films was investigated by TEM and X-ray techniques. The crystalline grain size was found to be 400 Å in diameter for S-films, and 800 Å in diameter for E-films. The x-ray diffraction patterns from a Read thin film camera revealed some preferred crystalline orientation for S-films. X-ray pole figures were taken for a closer measure of this texture. The results indicated that the S-films have (111) texture with their axes normal to the film plane. The magnetic properties for both films were observed with a MH loop tracer. Both films possessed low coercivity (about 1.5 Oe or less). The S-films were found to have in-plane magnetic anisotropy. Film stress and annealing effects were also studied. The differences of the observed resistivity and magnetic anisotropy for both films are attributed to an atomic ordering effect. The correlation of ΔR and texture is also discussed.