Royal Society of Chemistry, Journal of Materials Chemistry C Materials for optical and electronic devices, 39(2), p. 8259-8269, 2014
DOI: 10.1039/c4tc01316f
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Cobalt-indium (Co-In) heterogeneous films, featuring spatio-temporal patterns, have been electrodeposited in a chloride-citrate electrolyte. The Co content can be tuned from 25 at% to 90 at% by varying the applied current density between –10 and –30 mA cm–2. The spatio-temporal patterns consist of alternated dark and bright belts, which define micron-sized waves, targets and spirals. Cross-section images indicate a layer-by-layer growth. Several crystallographic phases (hexagonal close-packed Co, face-centered cubic Co, tetragonal In and tetragonal CoIn3) are identified in the corresponding X-ray diffractograms. The films combine large hardness with relatively large Young’s modulus and exhibit a soft-magnetic behaviour with tunable saturation magnetisation and coercivity (HC) values, mostly depending on the Co content and the effective magnetic anisotropy. The film with 90 at% Co shows the highest in-plane HC (275 Oe) and a squareness ratio close to 1. Magnetic force microscopy observations reveal that the self-patterning is not only topographic but also magnetic. These results demonstrate that electrodeposition of spatio-temporal structures is a simple method to grow magnetically-patterned films, over large areas, in a rapid and inexpensive way. This procedure is highly attractive for the implementation of new types of magnetic sensors, encoding magnetic stripes or even magnetic recording media.