Separation of Anisotropy Components in Magnetic Films by Study of the Temperature Dependence of the Anisotropy Field

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Abstract
The temperature dependence of Hk is a measure of the strength of interaction of the anisotropy-generating atomic configurations. In a film having several different anisotropy components, Hk(T) is therefore expected to be a superposition of several temperature dependencies. To obtain a separation, Hk(T) was measured at different stages of a magnetic anneal, during which the anisotropy components were (beginning with those activated at low temperatures) gradually reoriented into a direction in which, as a result of a new technique, they became excluded from the measurement. The function Hk(T) changed, indicating superimposed components having different temperature dependencies. Electroplated Ni–Fe–Cu and evaporated Ni–Fe–Co films were investigated. It was found that two major anisotropy sources exist. One, responsible for the annealing effects, has such a strong temperature dependence that it is unlikely to originate from a diatomic directional order. The temperature dependence of this component is independent of the degree of easy-axis stabilization. The other component (possibly due to atom pairs), is only weakly dependent on temperature, and does not measurably respond to magnetic annealing in the considered temperature interval (25°–170°C).