We propose to study electrodeposited films, both patterned and unpatterned, of CoNiCu alloy layers interleaved with pure Cu spacer layers. The magnetic layers are engineered such that each layer has a different coercivity and may be switched individually. These films are grown on a patterned substrate and onto a conductive release layer so they may be used as free floating magnetic barcodes. The barcodes can be hybridised with bio-chemical probes and the code written depending on the assay, thus enabling us to perform multiplexed assays. Understanding the magnetic microstructure of these films is of critical importance in being able to engineer them effectively. For this PNR is an ideal tool, being able to characterise both the film structure and the magnetic layers and give crucial interface information. The results will be complemented by conventional XRR, AFM and SQUID measurements.