Fullerton John, McCray Arthur R C, Petford-Long Amanda K, Phatak Charudatta
Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.
Applied Physics Program, Northwestern University, Evanston, Illinois 60208, United States.
Nano Lett. 2024 Feb 28;24(8):2481-2487. doi: 10.1021/acs.nanolett.3c04172. Epub 2024 Feb 19.
Comprehending the interaction between geometry and magnetism in three-dimensional (3D) nanostructures is important to understand the fundamental physics of domain wall (DW) formation and pinning. Here, we use focused-electron-beam-induced deposition to fabricate magnetic nanohelices with increasing helical curvature with height. Using electron tomography and Lorentz transmission electron microscopy, we reconstruct the 3D structure and magnetization of the nanohelices. The surface curvature, helical curvature, and torsion of the nanohelices are then quantified from the tomographic reconstructions. Furthermore, by using the experimental 3D reconstructions as inputs for micromagnetic simulations, we can reveal the influence of surface and helical curvature on the magnetic reversal mechanism. Hence, we can directly correlate the magnetic behavior of a 3D nanohelix to its experimental structure. These results demonstrate how the control of geometry in nanohelices can be utilized in the stabilization of DWs and control of the response of the nanostructure to applied magnetic fields.
理解三维（3D）纳米结构中几何形状与磁性之间的相互作用对于理解畴壁（DW）形成和钉扎的基本物理原理至关重要。在此，我们使用聚焦电子束诱导沉积来制造螺旋曲率随高度增加的磁性纳米螺旋。通过电子断层扫描和洛伦兹透射电子显微镜，我们重建了纳米螺旋的三维结构和磁化强度。然后从断层扫描重建中量化纳米螺旋的表面曲率、螺旋曲率和扭转。此外，通过将实验性三维重建作为微磁模拟的输入，我们可以揭示表面和螺旋曲率对磁反转机制的影响。因此，我们可以直接将三维纳米螺旋的磁行为与其实验结构相关联。这些结果表明了如何利用纳米螺旋中几何形状的控制来稳定畴壁并控制纳米结构对施加磁场的响应。
