Matteo Franchin

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Extensions of the basic micromagnetic model that include effects such as spin-current interaction, diffusion of thermal energy or anisotropic magnetoresistance are often studied by performing simulations that use case-specific ad-hoc extensions of widely used software packages such as OOMMF or Magpar. We present the novel software framework ‘Nmag’ that(More)
We present a new method to simulate repetitive ferromagnetic structures. This macro geometry approach combines treatment of short-range interactions (i.e. the exchange field) as for periodic boundary conditions with a specification of the arrangement of copies of the primary simulation cell in order to correctly include effects of the demagnetizing field.(More)
The performance of hard-magnetic nanostructures is investigated by analyzing the size and geometry dependence of thin-film hysteresis loops. Compared to bulk magnets, weight and volume are much less important, but we find that the energy product remains the main figure of merit down to very small features sizes. However, hysteresis loops are much easier to(More)
We review design and development decisions and their impact for the open source code Nmag from a software engineering in computational science point of view. We summarise lessons learned and recommendations for future computational science projects. Key lessons include that encapsulating the simulation functionality in a library of a general purpose(More)
We study field-driven domain wall (DW) motion in nanowires with perpendicular magnetic anisotropy using finite element micromagnetic simulations. Edge roughness is introduced by deforming the finite element mesh, and we vary the correlation length and magnitude of the roughness deformation separately. We observe the Walker breakdown both with and without(More)
A hybrid finite element method/boundary element method (FEM/BEM) is a standard approach for calculating the magnetostatic potential within Micromagnetics [1]. This involves dealing with a dense N ×N -matrix Bij , N being the number of mesh surface nodes. In order to apply the method to ferromagnetic structures with a large surface one needs to apply matrix(More)
In this article we present a systematic, numerical analysis of the magnetic properties of pyramidal-shaped core-shell structures in a size range below 400 nm. These are three dimensional structures consisting of a ferromagnetic shell which is grown on top of a non-magnetic core. The standard micromagnetic model without the magnetocrystalline anisotropy term(More)
Jürgen P. Zimmermann, Kevin Martin, Giuliano Bordignon, Matteo Franchin, Roger C. C. Ward, Graham J. Bowden, Peter A. J. de Groot, and Hans Fangohr 1 Computational Engineering and Design Group, School of Engineering Sciences, University of Southampton, SO17 1BJ, United Kingdom 2 School of Physics and Astronomy, University of Southampton, SO17 1BJ, United(More)
We review design and development decisions and their impact for the open source code Nmag from a software engineering in computational science point of view. We summarise lessons learned and recommendations for future computational science projects. Key lessons include that encapsulating the simulation functionality in a library of a general purpose(More)
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