Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Ultramicroscopy. 2010 Feb;110(3):177-81. doi: 10.1016/j.ultramic.2009.11.002. Epub 2009 Nov 18.
The magnetic vortex structure is an equilibrium configuration frequently found in patterned magnetic nanostructures. It is characterized by an in-plane curling of the magnetization with clockwise or anticlockwise chirality and by an out-of-plane vortex core that can have a positive or negative polarity. The small size of the vortex core, on the order of 10nm, makes it technologically interesting due to potential data storage, but also difficult to measure or image directly. In this work, we used Scanning Electron Microscopy with Polarization Analysis (SEMPA) to directly image magnetic vortex cores in patterned NiFe/Ta bilayer structures. With SEMPA we can simultaneously measure the in-plane and the out-of-plane component of the surface magnetization and thereby determine both the vortex chirality and the vortex core polarity in a single measurement. Our magnetic simulation of the vortex core, considering only the exchange and magnetostatic energy, is in good agreement with the SEMPA measurement of the magnetization when other experimental factors are taken into account.
磁涡旋结构是在图案化磁性纳米结构中经常发现的平衡构型。它的特征是磁化的面内卷曲，具有顺时针或逆时针的手性，以及具有正或负磁极的面外涡核。涡核的小尺寸，约为 10nm，由于潜在的数据存储，在技术上很有趣，但也很难直接测量或成像。在这项工作中，我们使用带有极化分析（SEMPA）的扫描电子显微镜（SEM）直接对图案化 NiFe/Ta 双层结构中的磁涡核进行成像。通过 SEMPA，我们可以同时测量表面磁化的面内和面外分量，从而在单次测量中确定涡旋的手性和涡核的极性。我们对仅考虑交换能和静磁能的涡核的磁性模拟，与考虑其他实验因素时 SEMPA 对磁化的测量结果吻合良好。
