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Concentration of magnetic flux at microscale
Střecha, Jan ; Wojewoda, Ondřej (referee) ; Staňo, Michal (advisor)
Magnetic concentrators are used to amplify the detected field by magnetic sensors or as cores in coils to direct the magnetic field. This work focuses on magnetic field concentrators at the microscopic scale and aims to design various metamaterials and geometries that could be used to enhance the magnetic field. The simulations use the program Mumax3, which employs the finite difference method and discretizes space into small cuboids to solve the time dependence of magnetization. Initially, the "petal" geometry was investigated, with a concentrator diameter of 5 m, and the simulated amplification value was determined upon applying an external field. Subsequently, metamaterials made of permalloy NiFe were created from the initial petal shape, consisting of small equilateral triangles with a size of less than 0.5 m, varying the distance between individual elements and their thickness. A petal with a thickness of 15 nm achieves an amplification of 2, while the examined geometries achieved amplifications of less than 1.2 for the same thickness. The results that achieved the highest value, around 1.8, were for thicknesses of 60 nm.
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