Sequence of TEM bright field images illustrating the evolution of Fe island morphology and interconnectivity with increasing Fe thickness along MgO 〈100〉, 〈011〉, and 〈012〉 zone axes. (a), (b); (c), (d); and (e), (f) correspond to 10, 20, and 30 nm Fe thicknesses, respectively. Insets show high resolution images of each Fe-MgO interface and arrows indicate the boundaries of the Fe-MgO intermixed region.
SEM plan-view images illustrating the evolution of Fe island morphology with thickness. (a) Discrete, equiaxed islands. (b) Connected, anisotropic islands new layer of discrete, equiaxed islands.
STEM-EDS maps of the intermixing of a 20 nm Fe island and the MgO substrate. From left to right, a bright field STEM image, Fe K edge map, and Mg K edge map are shown. The region between the dashed lines corresponds to an intermixed interface layer.
STEM-EELS maps of the interface between a 20-nm Fe film and the MgO substrate. (a) A series of spectra collected across the intermixed region at the points labeled in the inset of (b). (b) The calculated Fe L 3/L 2 peak ratios (squares) and the estimated Fe valence (triangles) from Cosandey et al. 23 Error bars correspond to the goodness of the Gaussian fit to the two peaks at each spot.
In-plane magnetic hysteresis loops for 10, 20, and 30 nm Fe films ((a)–(c), respectively) along the Fe 〈100〉 and 〈110〉 directions. (a) splitting between the two directions, while in (c) an obvious anisotropy exists between the 〈100〉 and 〈110〉 directions. (d) Coercivities along 〈100〉 and 〈110〉 directions for each sample, with a peak at 20 nm.
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