Co nanostructures in ordered templates: comparative FORC analysis

A comparative study on the structural and magnetic properties of highly ordered hexagonal arrays of Co nanoholes, nanowires, nanopillars and nanotubes, with tuned pore/wire/tube diameters, is here presented. The magnetic interactions and their dependence on the geometric features of the arrays were studied using first-order reversal curves (FORCs). For all nanostructures we observe an increase of the magnetostatic interactions with the templates' pore diameter, with the higher (smaller) values found for the nanowire (nanohole) arrays. For the smallest diameters studied (35 nm), all types of arrays could be considered as almost isolated nanostructures, where local interactions prevail. In particular, both nanotube and nanohole arrays exhibit considerable local magnetostatic interactions coming from the stray fields within each void or empty core. On the other hand, the coercivity is found to decrease with diameter for the elongated nanostructures, while it increases with the pore diameter for the nanohole arrays. This behavior is associated with the magnetization reversal mechanisms present in each array. This work highlights a versatile route to tailor the size, geometrical arrangement and magnetostatic interactions of ordered arrays and demonstrates their importance for the tuning of the magnetic behavior of nanometric devices. © 2013 IOP Publishing Ltd.This work was performed under support by the Spanish Ministry of Economia y Competitividad, through project MAT2010-20798-C05-01. M P Proenca, D C Leitao and C T Sousa acknowledge FCT for grants SFRH/BPD/84948/2012, SFRH/BPD/72359/2010 and SFRH/BPD/82010/2011, respectively. K J Merazzo thanks the University of Costa Rica and CSIC for the financial support. L G Vivas thanks the International Iberian Nanotechnology Laboratory (INL) for a studentship. J Ventura acknowledges financial support through FSE/POPH. The authors acknowledge funding from FCT through the Associated Laboratory—IN.Peer Reviewe