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We present the results of a Brillouin light scattering investigation of thermally excited spin wave eigenmodes in square arrays of either isolated rectangular dots of permalloy or twins of dipolarly coupled elements, placed side-by-side or head-to-tail. The nanodots, fabricated by e-beam lithography and lift-off, are 20nm thick and have the major size D in the range between 90nm and 150 nm. The experimental spectra show the presence of two main peaks, corresponding to modes localized either at the edges or in the center of the dots. Their frequency dependence on the dot size and on the interaction with adjacent elements has been measured and successfully interpreted on the basis of dynamical micromagnetic simulations. The latter enabled us also to describe the spatial profile of the eigenmodes, putting in evidence the effects induced by the dipolar interaction between coupled dots. In particular, in twinned dots the demagnetizing field is appreciably modified in proximity of the "internal edges" if compared to the "external" ones, leading to a splitting of the edge mode. These results can be relevant for the exploitation of sub-150 nm magnetic dots in new applications, such as magnonic metamaterials, bit-patterned storage media, and nano-magnetic logic devices. [ABSTRACT FROM AUTHOR]

We explore the switching mechanism of nanomagnet stacks that are patterned from a multilayered film and simultaneously exhibit strong shape anisotropy and antiferromagnetic exchange coupling between the ferromagnetic layers. We study the interplay of these two effects and demonstrate how they determine the switching characteristics of the magnets. Micromagnetic simulations give insight into the details of the magnetization reversal. These findings could be important in spintronic and magnetic logic applications, where both the shape and interlayer interactions can be exploited to tailor the properties of the magnetic building blocks of these devices. [ABSTRACT FROM AUTHOR]

We study the ferromagnetic resonance (FMR) modes of arrays consisting of elements of supermalloy-based nanomagnet logic devices: individual rectangular magnets, lengthwise-coupled magnet pairs, and driver-input magnet pairs. In FMR experiments, we observe a center resonance mode for all three samples. Furthermore, edge modes can be resolved for arrays with individual rectangular magnets and lengthwise-coupled magnet pairs. By micromagnetic simulations, the characteristics of the experimentally observed precession modes are elaborated, and distinct edge modes not visible in the experiments are revealed. Based on these numerical investigations, we propose a new addressing scheme to switch a specific element of the driver-input magnet pair based on resonant excitation of the unique edge-mode resonance of the element. This new switching scheme could significantly reduce switching power and increase bit selectivity, and hence programming reliability. [ABSTRACT FROM AUTHOR]