Tailoring the magnetization states in 2D arrays of multiresponse ferromagnetic nanomagnets

Abstract

We have fabricated Fe 52−54 Co 46−48 nanomagnet arrays as a function of several geometrical parameters like the spacing between nanostructures, the aspect ratio and the layers thicknesses. The nanomagnets consist in two magnetic layers, separated by a non magnetic interlayer, that interact through magnetostatic coupling. They present a multiresponse hysteresis loops with two dierent switching elds. We have performed micromagnetic simulations to discern the role play by the dierent interactions. The spacing in the array strongly modies the saturating eld along the short axis and the magnetization reversal mechanisms from coherent rotation to domain wall nucleation. A small asymmetry between the two magnetic layers favors a magnetization reversal mechanism along the long axis with two dierent switching elds. These elds can be tailored through the thickness of the layers or the inter-element spacing in the array. In trilayers with the same magnetic layer thicknesses, the asymmetry can be induced by growing the two magnetic layers with a dierent anisotropy. The well-dened reversal elds make these nanomagnets potentially useful for magnetic tagging.

Experimental set-up for exciting and detecting magneto-optical effects and surface plasmon resonance simultaneously

“…In order to illustrate the resolution of the system with this vertical configuration, provided in [22]). The set-up allows recording the magneto-optical signal with resolution good enough to clearly identify the hysteresis loops corresponding to the top and bottom layers.…”