We have identified an important microstructural origin of the switching field distribution (SFD) in patterned Co/Pd multilayer nanodots. In this study, we patterned a marked array of 115 nm Co/Pd multilayered nanodots on 50-nm thick silicon nitride substrate. We identified the dots with unusually small and large switching fields (>2 standard deviations of the mean switching field) with MFM, followed by microstructural characterization of the same dots in plan-view with TEM. From selected area electron diffraction, we found that most nanodots with small switching fields have strong, discrete, (200) spots, whereas those with large switching fields lack these spots. While bright-field TEM images reveal an average grain size of 7 nm, dark-field images of the (200) spots reveal on average, a single grain of >10 nm in lateral dimensions. Since we observed a direct correlation between strong (200) reflections and small reversal fields, we conclude that the largest grain in each nanodot, with an in-plane  is the likely cause for premature switching, which in turn defines the SFD of this array.
Citation: Applied Physics Letters
Pub Type: Journals
grain orientation, microstructure, switching field distribution