{"id":220,"date":"2023-07-14T19:11:31","date_gmt":"2023-07-14T17:11:31","guid":{"rendered":"https:\/\/webs.uab.cat\/simmas\/?page_id=220"},"modified":"2025-10-17T20:29:24","modified_gmt":"2025-10-17T18:29:24","slug":"research-line-micromagnetism","status":"publish","type":"page","link":"https:\/\/webs.uab.cat\/simmas\/research-line-micromagnetism\/","title":{"rendered":"Micro- and nano-magnetism at SiMMaS"},"content":{"rendered":"\n

Some topics developed at SiMMaS<\/h2>\n\n\n\n
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Skyrmions<\/em><\/strong><\/summary>
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Transport of skyrmions on racetracks. <\/em><\/strong><\/summary>
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Magnetic skyrmions can be considered as magnetic bits due to their nanometric size and topologically protected stability. We have studied the dynamics of such skyrmions in racetrack geometries and, in general, in confined geometries. Analytical expressions for the trajectories of skyrmions in confined geometries (including long tracks and square samples) when driven by polarised electric currents. The force exerted by the borders is derived as a function of the material parameters (anisotropy, Dzyaloshinskii-Moriya, and exchange constants) and incorporated in the equation of motion of the skyrmions.<\/p>\n\n\n\n

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Trajectories for a skyrmion with squared borders, for the case of ac driving current of different values of frequencies. A resonance effect is seen in the third picture. The value of the driving current is the same in all cases<\/figcaption><\/figure>\n<\/div>\n\n\n\n
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Trajectories of a rigid skyrmion for\u00a0different driving currents and borders.<\/figcaption><\/figure>\n<\/div>\n<\/div>\n\n\n\n

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Skyrmions, as bits of information, can be transported along nanoracetracks. However, temperature, defects, and\/or granularity can produce diffusion, pinning, etc. These effects may cause undesired errors in information transport may compromise the feasibility of the device. We have performed simulations of a realistic system where both the (room) temperature and sample granularity are taken into account. Key feasibility magnitudes, such as the success probability of a skyrmion traveling a given distance along the racetrack, are calculated. The model proposed is based on the Fokker\u2013Planck equation resulting from Thiele’s rigid model for skyrmions.<\/p>\n\n\n\n

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Defects are unavoidable in real materials. Defects, either intrinsic or artificially incorporated, can alter the material properties. In the particular case of skyrmionic ferromagnetic materials, defects modify the stability and dynamics of the skyrmions. These magnetic structures have aroused great interest due to their potential as information carriers. Hence, the knowledge and control of the influence of defects on skyrmions are essential for their use in applications, such as magnetic memories or information mobility. We have studied how these defects affect the mobility of skyrmions and have also studied different ways to model them.<\/p>\n\n\n\n

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Dynamics of skyrmions with different types of defects (attractive-repulsive) and different magnitudes of driving currents.<\/figcaption><\/figure>\n<\/div>\n\n\n\n
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Probability density of finding the centre of a skyrion along three racetracks in which a random distribution of defects with different “intensities” has been considered.
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More information: <\/p>\n\n\n\n