Adhikari S, Li J, Wang Y, Ruijs L, Liu J, Koopmans B, Orrit M, Lavrijsen R
Huygens-Kamerlingh Onnes Laboratory, LION, 2300 RA Leiden, Netherlands.
Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, Netherlands.
ACS Photonics. 2023 Apr 28;10(5):1512-1518. doi: 10.1021/acsphotonics.3c00123. eCollection 2023 May 17.
Synthetic antiferromagnetic nanoplatelets (NPs) with a large perpendicular magnetic anisotropy (SAF-PMA NPs) have a large potential in future local mechanical torque-transfer applications for e.g., biomedicine. However, the mechanisms of magnetization switching of these structures at the nanoscale are not well understood. Here, we have used a simple and relatively fast single-particle optical technique that goes beyond the diffraction limit to measure photothermal magnetic circular dichroism (PT MCD). This allows us to study the magnetization switching as a function of applied magnetic field of single 122 nm diameter SAF-PMA NPs with a thickness of 15 nm. We extract and discuss the differences between the switching field distributions of large ensembles of NPs and of single NPs. In particular, single-particle PT MCD allows us to address the spatial and temporal heterogeneity of the magnetic switching fields of the NPs at the single-particle level. We expect this new insight to help understand better the dynamic torque transfer, e.g., in biomedical and microfluidic applications.
具有大垂直磁各向异性的合成反铁磁纳米片（SAF-PMA NPs）在未来诸如生物医学等局部机械扭矩传递应用中具有巨大潜力。然而，这些结构在纳米尺度上的磁化翻转机制尚未得到很好的理解。在此，我们使用了一种简单且相对快速的单粒子光学技术，该技术超越了衍射极限，用于测量光热磁圆二色性（PT MCD）。这使我们能够研究直径为122 nm、厚度为15 nm的单个SAF-PMA NPs的磁化翻转随外加磁场的变化。我们提取并讨论了大量纳米粒子集合与单个纳米粒子的翻转场分布之间的差异。特别是，单粒子PT MCD使我们能够在单粒子水平上研究纳米粒子磁翻转场的空间和时间异质性。我们期望这一新见解有助于更好地理解动态扭矩传递，例如在生物医学和微流体应用中。
