TY - JOUR AB - Magnetic nanoparticles can be used for medical and other purposes, but can also be integrated in polymeric or other nonmagnetic matrices of diverse shapes, for example, thin-films or fibers. In the latter case, it may be important how the magnetic nanoparticles are distributed in the matrix, a topic which is often not taken into account when such composites are investigated experimentally or theoretically. Especially for small magnetic nanoparticles of dimensions allowing coherent reversal, the magnetic properties of such polymer/magnet composites can change drastically in the case of agglomerations. Here, a method is suggested to quantify the influence of nanoparticle distributions inside nonmagnetic matrices. By changing the average distance between nanoparticles of varying diameters between highly distributed particles and perfectly packed clusters, different magnetization dynamics can be modeled by micromagnetic simulations. Here, this process is shown for various magnetic materials and diameter distributions of magnetic nano-spheres and present corresponding micromagnetic simulation results, which underline the importance of taking into account possible magnetic agglomerations in nonmagnetic space. AU - Blachowicz, Tomasz AU - Grzybowski, Jacek AU - Ehrmann, Andrea ID - 2027 IS - 1 JF - Macromolecular Symposia KW - iron KW - collapse KW - cross-section KW - permalloy KW - spherical coordinates KW - virtual sphere SN - 1022-1360 TI - Micromagnetic Simulations of Nanoparticles with Varying Amount of Agglomeration VL - 402 ER - TY - JOUR AB - Magnetic vortices belong to the possibilities to store information in magnetic structures. Understanding their nucleation and propagation is also of interest in basic research. While vortices are usually examined in particles of homogeneous material, here we give an overview of the impact of borders between two materials, i.e. iron and permalloy, on magnetization reversal and vortex formation in double-wedges as well as adjacent rectangles of different thickness. While former investigations of pure iron nanoparticles of similar dimensions revealed different magnetization reversal magnetisms without vortex, with one or two vortices, the addition of a permalloy part stabilized the magnetization reversal so that in all situations under investigation, a single vortex was observed. Our simulations underline the technological importance of such double-material structures for the preparation of nanostructures for storage devices with reliable magnetization reversal processes, stable against erroneous modifications of nanoparticle dimensions and magnetic field orientations. AU - Sudsom, Devika AU - Blachowicz, Tomasz AU - Hahn, Lothar AU - Ehrmann, Andrea ID - 669 JF - Journal of Magnetism and Magnetic Materials KW - Magnetic nanostructures KW - Wedges KW - Micromagnetic simulation KW - Vortex KW - Magnetization reversal KW - Iron KW - Permalloy KW - Lithography SN - 0304-8853 TI - Vortex nucleation and propagation in magnetic double-wedges and semi-squares for reliable quaternary storage systems VL - 514 ER - TY - JOUR AB - Magnetic vortex structures are of high technological relevance due to their possible application in magnetic memory. Moreover, investigating magnetization reversal via vortex formation is an important topic in basic research. Typically, such vortices are only investigated in homogeneous magnetic materials of diverse shapes. Here, we report for the first time on micromagnetic simulation of vortex formation in magnetic bow-tie nanostructures, comprising alternating parts from iron and permalloy, investigated for two different thicknesses and under different angles of the external magnetic field. While no vortex was found in pure permalloy square, nanoparticles of the dimensions investigated in this study and in case of iron only a relatively thick sample allowed for vortex formation, different numbers of vortices and antivortices were found in the bow-tie structures prepared from both materials, depending on the angular field orientation and the sample thickness. By stabilizing more than one vortex in a confined nanostructure, it is possible to store more than one bit of information in it. Our micromagnetic simulations reveal that such bi-material structures are highly relevant not only for basic research, but also for data storage applications. AU - Sudsom, Devika AU - Juhász Junger, Irén AU - Döpke, Christoph AU - Blachowicz, Tomasz AU - Hahn, Lothar AU - Ehrmann, Andrea ID - 635 IS - 1 JF - Condensed Matter KW - magnetic nanostructures KW - micromagnetic simulation KW - bow-tie structure KW - vortex KW - magnetization reversal KW - iron KW - permalloy KW - lithography SN - 2410-3896 TI - Micromagnetic Simulation of Vortex Development in Magnetic Bi-Material Bow-Tie Structures VL - 5 ER -