Institut für Experimentalphysik/Festkörperphysik, Fakultät für Physik and Astronomie, Ruhr-Universität Bochum, Bochum 44780, Germany.
Phys Rev Lett. 2013 Apr 26;110(17):177209. doi: 10.1103/PhysRevLett.110.177209.
We have studied the magnetic interaction of circular magnetic islands with a dipole character on a square lattice. The square pattern consists of lithographically prepared polycrystalline PdFe islands, 150 nm in diameter and a periodicity of 300 nm. Below the Curie temperature at 260 K, the islands are in a single domain state with isotropic in-plane magnetization. Below 160 K, there is an onset of interisland interaction that leads to a change of the shape of the hysteresis, an increase of coercivity, and a development of in-plane anisotropy. Photoemission electron microscopy with circularly polarized incident x rays tuned to the L3 edge of Fe confirms the increasing correlation of the magnetic islands and the formation of elongated chains, as predicted by Vedmedenko et al. [Phys. Rev. Lett. 95, 207202 (2005)] for contributions from pole interactions of higher order than the dipolar one. Neighboring chains are found to be irregularly oriented either parallel or antiparallel.
我们研究了具有偶极子特征的圆形磁性岛在正方形晶格上的磁相互作用。正方形图案由光刻制备的多晶 PdFe 岛组成，直径为 150nm，周期为 300nm。在 260K 的居里温度以下，这些岛屿处于各向同性面内磁化的单畴状态。在 160K 以下，会出现岛间相互作用，导致磁滞回线形状的变化、矫顽力的增加和面内各向异性的发展。用圆形偏振入射 X 射线调谐到 Fe 的 L3 边缘的光发射电子显微镜证实了磁性岛的相关性增加，并形成了拉长的链，这正如 Vedmedenko 等人[Phys. Rev. Lett. 95, 207202 (2005)]所预测的那样，这是由于高于偶极子的高阶磁极相互作用的贡献。发现相邻的链以不规则的平行或反平行方向取向。
