Search

Micromagnetic simulations are used to investigate the effects of different absorbing boundary layers (ABLs) on spin waves (SWs) reflected from the edges of a magnetic nano-structure. We define the conditions that a suitable ABL must fulfill and compare the performance of abrupt, linear, polynomial and tan hyperbolic damping profiles in the ABL. We first consider normal incidence in a permalloy stripe and propose a transmission line model to quantify reflections and calculate the loss introduced into the stripe due to the ABL. We find that a parabolic damping profile absorbs the SW energy efficiently and has a low reflection coefficient, thus performing much better than the commonly used abrupt damping profile. We then investigated SWs that are obliquely incident at 26.6 ° , 45 ° and 63.4 ° on the edge of a yttrium-iron-garnet film. The parabolic damping profile again performs efficiently by showing a high SW energy transfer to the ABL and a low reflected SW amplitude. [ABSTRACT FROM AUTHOR]

Abstract: We report the use of electron beam lithography and a bilayer liftoff process to fabricate magnetic Ni nanostructures with constriction widths in the range of 22–41nm. The structures fabricated correspond to the nanobridge geometry. Reproducibility and control over the final nanostructure geometry were observed when using the fabrication process introduced, these two qualities are important in order to carry out a more systematic analysis of domain wall magnetoresistance (DWMR). On the other hand, micromagnetic simulations of structures with the nanobridge geometry were carried out using not only the dimensions of the fabricated nanostructures but also smaller dimensions thought to be achievable with further optimization of the fabrication process. It was found that domain walls with a reduced length of 42.5nm can be obtained using the nanobridge geometry. Furthermore, the anisotropic magnetoresistance (AMR) effect was calculated numerically and it was found to be smaller than the DWMR, this makes the nanobridge geometry a good candidate for future measurements of the magnetoresistive effect due to domain wall scattering. [Copyright &y& Elsevier]

Abstract: Using a self-assembly double template method, we have prepared highly ordered magnetic dot arrays of Ni on sub-micron scales. For the template preparation we have used colloidal suspensions of polystyrene latex spheres with different diameters ranging from 200 to 700nm combined with secondary templates of the conducting polymer polypyrrole. By variation of the template parameters and the deposition charge the material shape can be modified significantly from isolated dots to connected 3D networks. Samples have been characterized by magnetometry. Magnetic properties were found to depend strongly on dot size and connectivity leading to a rich variety of magnetic behaviors. [Copyright &y& Elsevier]

We present results of electrochemical deposition of magnetic metals and alloys in the pores of templates prepared by self-assembly from colloidal suspensions of polystyrene latex spheres. This technique has enabled us to create highly ordered magnetic nano-structures with 3D architectures on length scales ranging from 50–1000 nm. Varying the parameters in the preparation (sphere diameter, film thickness and composition) allows us to produce materials with predetermined magnetic parameters. [Copyright &y& Elsevier]

Abstract: We have succeeded in aligning self-assembled structures by using a lithographically defined stripe. The 140nm wide by 100nm high SiO2 strip is shown to guide the assembly of 500nm latex spheres so that spheres are aligned along the strip and are in registration on either side of the strip. This method can be used to increase long-range ordering in magnetic storage systems without compromising the density. Inverse sphere Ni arrays were made by electrodeposition through the latex template. We also show that the hexagonal symmetry of the resulting inverse sphere Ni arrays can be simulated using the approach presented below. [Copyright &y& Elsevier]

Abstract: Electrodeposition of magnetic metals through self-assembly templates from polystyrene spheres is used for fabrication of magnetic nanostructures with 3-D architectures. These arrays demonstrate unusual properties including an oscillatory dependence of the coercive field on film thickness. Numerical simulations reveal that the ratio between the array period and the hole diameter in anti-dot array is a crucial parameter giving rise to qualitatively distinct magnetization reversal regimes. [Copyright &y& Elsevier]