Development of measuring method for the three-dimensional high frequency micro-magnetic stray fields extending beyond a magnetic head by reflection electron tomography

提出了一种用反射电子层析技术测量磁头外三维高频微磁杂散场的新方法。该方法以层析技术为基础，利用电子束在穿过磁场时被洛伦兹力偏转的偏转矢量重建磁场。在这种方法中，电子束与样品表面成直角注入，同时定期扫描其注入位置，并测量穿过磁场并从样品表面反射的电子束的偏转矢量。根据这些数据，使用ART(代数重建技术)方法(代数重建技术)迭代地重建在该区域延伸的三维杂散场，并使用边界元方法(BEM)来计算磁场分布。用已知的单圈线圈磁场模型对该方法进行了计算机模拟，数值结果表明，该方法可以计算出样品外的三维磁场分布，误差在20%左右。从这些实验结果中，证实了我们的方法可以应用于微杂散场的测量，就在间隙区域之外。

A new method for measuring the three-dimensional high frequency micro-magnetic stray fields extending beyond a magnetic head by reflection electron tomography are developed. This method is based on tomographic technique, in which the magnetic fields are reconstructed from the deflection vectors of the electron beams deflected by the Lorentz force when traversing through magnetic fields. In this method, the electron beams are injected at right angles to the surface of a specimen, while scanning their injection positions regularly, and the resulting deflection vectors of the electron beams traversing through the magnetic fields and being reflected from the surface of the specimen are measured. From these data, the three-dimensional magnetic stray fields extending over in this region are iteratively reconstructed by an ART method (Algebraic Reconstruction Technique) using the BEM (Boundary Element Method) for calculating the magnetic field distribution. Our proposed method is tested with a known magnetic field model of one-turn coil by computer simulation.It is shown numerically that the field distribution just beyond the specimen can be evaluated three dimensional with an error of around 20 %. And from these experimental results, it is confirmed that our method can be applicable to the measurement of micro-magnetic stray fields just beyond the gap region.