Angular dependence of switching field distribution in (Co/Pd)n multilayer nanostructure arrays

Abstract

The characterization of switching field and its angular dependence has been tremendously useful in understanding the switching mechanisms in magnetic thin-films and patterned structures. However, the study of the distribution in switching fields (SFD) in arrays and its angular dependence is less common. In this work, we investigate this dependency in arrays of (Co/Pd)n multilayer nanostructures. Results from arrays with different element sizes and periodicities (pitches) are presented, and we found that, like the switching field, the SFD varies with applied field angle in a Stoner-Wohlfarth-like fashion. Furthermore, when the SFD is represented as a dependent variable of the switching field, we consistently found a linear relationship between the two, and that the slope depends on both array element size and pitch. In general, the SFD in arrays with the largest structures and the smallest pitch tends to have the strongest dependence on the switching field. For arrays with nanostructures of a fixed size, however, we found that SFD values are virtually identical, regardless of pitch, if the reversal field is applied near 45° with respect to the surface normal. That the minimum SFD depends only on the size of the elements and not the pitch has significant implications for the practical design of densely-packed magnetic nanostructure arrays.