Programmable Locomotion Mechanisms of Nanowires with Semihard Magnetic Properties Near a Surface Boundary
| Autor: | Bradley J. Nelson, Ayoung Hong, Carlos Alcantara, Jordi Sort, Yuval Harduf, X. Marti, Yizhar Or, George Chatzipirpiridis, Eva Pellicer, Salvador Pané, Bumjin Jang |
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| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Surface (mathematics) 0303 health sciences Rotating magnetic field Materials science Condensed matter physics Alloy Nanowire Boundary (topology) engineering.material 01 natural sciences Magnetic field Condensed Matter::Materials Science 03 medical and health sciences Magnetization 0103 physical sciences Precession engineering General Materials Science 030304 developmental biology |
| Zdroj: | ACS Applied Materials & Interfaces. 11:3214-3223 |
| ISSN: | 1944-8252 1944-8244 |
| Popis: | We report on the simplest magnetic nanowire-based surface walker that is able to change its propulsion mechanism near a surface boundary as a function of the applied rotating magnetic field frequency. The nanowires are made of CoPt alloy with semihard magnetic properties synthesized by means of template-assisted galvanostatic electrodeposition. The semihard magnetic behavior of the nanowires allows for programming their alignment with an applied magnetic field as they can retain their magnetization direction after premagnetizing them. By engineering the macroscopic magnetization, the nanowires' speed and locomotion mechanism are set to tumbling, precession, or rolling depending on the frequency of an applied rotating magnetic field. Also, we present a mathematical analysis that predicts the translational speed of the nanowire near the surface, showing a very good agreement with experimental results. Interestingly, the maximal speed is obtained at an optimal frequency (∼10 Hz), which is far below the theoretical step-out frequency (∼345 Hz). Finally, vortices are found by tracking polystyrene microbeads, trapped around the CoPt nanowire, when they are propelled by precession and rolling motion. |
| Databáze: | OpenAIRE |
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