Programmable Locomotion Mechanisms of Nanowires with Semihard Magnetic Properties Near a Surface Boundary

Bumjin Jang, Ayoung Hong, Carlos Alcantara, George Chatzipirpiridis, Xavier Martí, Eva Pellicer, Jordi Sort, Yuval Harduf, Yizhar Or, Bradley J. Nelson, Salvador Pané

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
Pages (from-to)3214-3223
Number of pages10
JournalACS Applied Materials and Interfaces
Volume11
Issue number3
DOIs
StatePublished - 23 Jan 2019

Keywords

  • CoPt nanowires
  • boundary effect
  • motion transition
  • nanopropulsion
  • semihard magnetic properties

All Science Journal Classification (ASJC) codes

  • General Materials Science

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