A 2.5D micromagnetic solver for randomly distributed magnetic thin objects

This paper presents a GPU-parallelized 2.5D micromagnetic solver for the efficient calculation of the magnetization configuration and hysteresis loop of 3D random distributions of magnetic thin-film objects, strongly interacting in the space. To well-reproduce complex shapes, the exchange field is calculated with a finite difference approach able to handle non-structured meshes. To enable the treatment of many objects, the magnetostatic field is locally separated into two contributions: an internal and an external one. The first term includes the magnetostatic interactions internal to each object and is obtained by numerically solving the Green's integral equation. The second term describes the inter-object magnetostatic interactions and it is determined by approximating each object as a collection of magnetic dipoles, associated with mesh elements. The accuracy and computational efficiency of the solver are analysed by comparison to a standard 3D-FFT code and to a reference code, where all the magnetostatic field terms are evaluated by numerically solving the Green's integral equation.