磁力顯微術在磁性薄膜表面的檢測與分析

Abstract

磁力顯微術是近年來發展的一項對表面磁化結構具有高解析度的顯微技術，其解析度一般大約在50奈米(nm)，甚至在良好環境操作下可達20nm。由於其具有高解析度以及操作容易，因此我們選其作為研究磁性薄模表面的技術。 在論文的第一部份，我們觀測到市面上的Floppy Disk以及Digital Tape上的磁記錄單原與本質磁區，並且也計算兩者的記錄密度做比較。而在第二部份則鐵磁性材料的磁區結構。並且在鈷薄膜上觀測到了三種磁壁種類，如 Bloch wall、N'eel wall以及Cross-tie wall等，並量得其磁壁厚度，進而與理論計算做一比較。另外我們也利用此項技術所觀察到的磁區影像，而簡單地繪出不同磁區內的磁化形態。最後我們也做了一些巨磁組薄膜上初步的簡單分析。

Magnetic Force Microscopy(MFM) is a technique with high resolution for mapping surface magnetic structure. The resolution of MFM is typically around 50nm, and achieves 20nm under well controlled environment. Because of its high resolution and ease of use, we choose it for the investigation of surface magnetic structures on magnetic thin films. For the first part of the thesis, we analyze the qualities of the recording bits and intrinsic domains on a 1.44M floppy disk and a digital tape. The recording densities for both media are also calculated. The second part of the thesis deals with the examination of the magnetic domains on ferromagnetic thin films. Three different kinds of magnetic domain walls, i.e., Bloch, N'eel and cross-tie walls are all observed. The wall thicknessses for cobalt thin film are measured, and theoretical values are also calculated in comparison with the experimental ones. The directions of magnetization indifferent domain walls are also determined. Finally, we present preliminary data on giant magneto-resistance(GMR) thin films on different substrates.