Talapatra A, Adeyeye A O
Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576.
Nanoscale. 2020 Oct 22;12(40):20933-20944. doi: 10.1039/d0nr06026g.
This paper investigates the control of effective magnetic anisotropy in Permalloy linear chain arrays, achieved by tuning the symmetry arrangement of the ellipsoidal nanomagnets and the film thickness. When the ellipsoidal nanomagnets are coupled along their easy axis, stronger effective magnetic anisotropy is achieved compared to when the nanomagnets are coupled along their hard axis. A clear transition from a single domain state to a combination of complex flux closure states such as a vortex or double vortices is observed at different applied field angles when the film thickness is varied in the range from 20 nm to 100 nm. Tunable microwave absorption spectra, obtained by ferromagnetic resonance spectroscopy, established the complex interplay between the shape anisotropy and magnetostatic interactions, which becomes more intriguing at different film thicknesses and applied field angles. The micromagnetic simulations are in good agreement with the experimental results. Our results demonstrate possible ways of manipulating the effective magnetic anisotropy in arrays of nanomagnets for magnonic and microwave applications.
本文研究了通过调整椭球形纳米磁体的对称排列和薄膜厚度来控制坡莫合金线性链阵列中的有效磁各向异性。当椭球形纳米磁体沿其易轴耦合时，与沿其难轴耦合相比，可实现更强的有效磁各向异性。当薄膜厚度在20纳米至100纳米范围内变化时，在不同的外加磁场角度下，观察到从单畴状态到诸如涡旋或双涡旋等复杂磁通闭合状态组合的清晰转变。通过铁磁共振光谱获得的可调谐微波吸收光谱，确立了形状各向异性与静磁相互作用之间的复杂相互作用，这在不同的薄膜厚度和外加磁场角度下变得更加引人入胜。微磁模拟与实验结果吻合良好。我们的结果展示了在纳米磁体阵列中操纵有效磁各向异性以用于磁子和微波应用的可能方法。
