The interaction field in arrays of ferromagnetic barcode nanowires

A theoretical model and an experimental approach to the identification of the interaction field in ferromagnetic barcode nanowires are described and applied to electrodeposited Ni/ Au cylindrical barcode arrays. Elementary hysteresis loops of individual magnetic segments in these barcode nanowires are considered as superpositions of fully irreversible and locally reversible magnetization processes, whose distributions of switching fields are experimentally identified by first order reversal curve measurements. Non- interacting major hysteresis loops of the arrays are computed as superpositions of several elementary loops by considering the distributions of switching fields as probability density functions. The interaction field is then computed from the condition that the geometric transformation of the experimental major hysteresis loop into the Preisach operative plane be well approximated by this non- interacting hysteresis loop. Experimental interaction field values are compared with those obtained by numerical micromagnetic computations and a very good agreement is obtained on extended Ni/ Au barcode arrays. The simple and accurate phenomenological model for the interaction field in multisegmented ferromagnetic nanowire arrays proposed here provides an insight into the morphology of these magnetic nanomaterials, as quantitative information about individual nano- objects may be extracted from macroscopic measurements of their arrays.