Snoeck E, Gatel C, Lacroix L M, Blon T, Lachaize S, Carrey J, Respaud M, Chaudret B
CNRS, CEMES, F-31055 Toulouse, France.
Nano Lett. 2008 Dec;8(12):4293-8. doi: 10.1021/nl801998x.
Ferromagnetic nanomaterials exhibit unique magnetic properties common to materials with dimensions approaching the atomic scale and have potential applications in magnetic data storage. Technological applications, however, require that the detailed magnetic behaviors and configurations of individual and interacting magnetic nano-objects be clarified. We determined the magnetic remnant configurations in single crystalline 30 nm Fe nanocubes and groups of nanocubes using off-axis electron holography in a transmission electron microscope. Our measurements on an isolated cube reveal a vortex state whose core size has been determined. Two neighboring nanocubes with adjacent {100} surfaces exhibit a ferromagnetic dipolar coupling, while similar magnetic interactions between four cubes in a square arrangement induce a bending of the magnetic induction, i.e., a magnetic flux closure state. The various configurations were successfully simulated by micromagnetic calculations.
铁磁纳米材料展现出与尺寸接近原子尺度的材料共有的独特磁性，并且在磁数据存储方面具有潜在应用。然而，技术应用要求明确单个和相互作用的磁性纳米物体的详细磁行为和构型。我们使用透射电子显微镜中的离轴电子全息术确定了单晶30纳米铁纳米立方体以及纳米立方体群组中的剩余磁构型。我们对单个立方体的测量揭示了一种已确定其核心尺寸的涡旋态。两个具有相邻{100}面的相邻纳米立方体表现出铁磁偶极耦合，而正方形排列的四个立方体之间的类似磁相互作用会引起磁感应的弯曲，即磁通量闭合态。通过微磁学计算成功模拟了各种构型。
