New data-acquisition system for spin-polarized scanning electron microscopy (abstract)

Abstract

A new data-acquisition system suitable for spin-polarized scanning electron microscopy used in magnetic domain observation has been developed. The system is composed of a primary-electron-beam scan controller, four counters of two pairs of output signals coming from a spin polarization detector, an image processor with two high-speed digital signal processors calculating the polarization-components Px and Py from the detector outputs, 32 frame memories (512×512×16 bit) for the detector outputs, Px, Py, sample absorbed current, etc., as well as a 1280×1024 pixel monitor. The system enables not only high-speed scanning (21 s/image) for a quick view but also very slow-speed scanning (≳1 h/image) for a high-quality image. With this variable-speed scanning, it is possible to promptly obtain a homogeneous quality image even when the secondary-electron intensity distribution is inhomogeneous due to the surface topography. By calculating the magnitude and direction of magnetization from Px and Py, magnetization vectors can be represented as arrows in the domain image. The system has been successfully applied to domain observation of an iron single crystal and a magnetic recording head having a three-dimensional surface structure as well as side plane observation of multilayered films for a magnetic recording head.