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Additive patterning processes of magnetic films grown using an ion-beam sputter (IBS) system designed to produce non-conformal films are described. The effects of the ion-gun beam current and Ar pressure on the sputtering rates and roughness of Ni80Fe20 and Co70Fe30 magnetic thin films are investigated using atomic-force microscopy (AFM) and the films’ magnetic properties are measured using spatially resolved magneto-optical magnetometry. By tailoring the plasma solid angle, non-conformal film growth allows for simple additive patterning down to lateral dimensions ranging from a few microns to the deep-submicron regime, using templates defined by photolithography or electron-beam lithography, and shadow masks created using templated self-assembly. The magnetization reversal exhibited by patterned sub-200 nm nanodisc arrays with different lateral edge-roughness will be discussed.

The stability of the magnetic state of individual elements within patterned nanoarrays depends on the balance of interelement interactions and shape anisotropy. These effects were studied by ferromagnetic resonance and alternating gradient magnetometry to characterize large area hexagonal arrays of 20nm thick 190nm wide elliptical Permalloy elements with aspect ratios 1.6 and 3.6, made using interference lithography, electron beam evaporation, and lift-off processing. The in-plane anisotropy of short ellipses is 42mT, as compared to the 86mT in-plane anisotropy of ellipses twice as long. The out-of-plane anisotropy field is about 650mT, similar for both systems. Separation dependence of the interelement interactions was modeled numerically. The significant contribution from far neighbors to the interaction field is about 20mT, comparable to the switching field of soft magnetic materials.

The combined influence of shape anisotropy, dipolar interactions and exchange bias (EB) on the magnetization reversal of arrays of NiFe and NiFe/IrMn sub-micrometre elliptical magnetic elements has been investigated using magneto-optical Kerr effect microscopy and micromagnetic modelling. An applied field during film growth resulted in exchange fields around 50 Oe for the unpatterned films, micrometre sized stripes and nanomagnet arrays. High aspect ratio single-layer ellipses reverse via a single-domain-like switching while low aspect ratio structures reverse through the movement of a vortex core. The vortex formation and annihilation fields for closely spaced elliptical elements depend on the inter-element spacing and the aspect ratio. In particular, the stability range of the vortex state is lower for more strongly interacting or higher aspect ratio structures. On the other hand, a modest EB can significantly increase the stability of the vortex states and promote single-domain states that lead to different remanent configurations. A combination of EB, shape and inter-element spacing can therefore be used to tailor the behaviour of coupled nanomagnet arrays.