Development of Observation Method of Fine Magnetic Domains using Spin Polarized Electron Detection Probe

在这项研究中，开发用于检测磁性材料中磁畴中电子自旋极化的探针是非常重要的，例如用于磁记录系统特别是垂直磁记录系统的磁性薄膜介质。这些探针使用光刻技术制造。首先，在衬底上涂覆光刻胶（OFPR）层，并在其上淀积铝膜，再利用光刻技术在铝膜上制备出直径约为几μ m的微孔。采用等离子体灰化方法，利用氧气混合等离子体消除了孔下的光刻胶。当溅射粒子通过孔沉积在衬底上时，将形成探针。利用蒙特-卡罗模拟技术，阐明了孔的直径和光刻胶层的厚度的深宽比与探针轮廓的关系。小的纵横比导致沉积的探针的尖锐轮廓。自旋隧穿现象是本研究的重点之一，因为探针必须探测到电子的自旋极化，这些电子通过隧穿效应从目标材料中的磁畴到达探针。为了研究自旋隧道效应，我们采用Ni-Fe/Si_3N_4/Ni-Fe夹层结构，并在夹层结构中加入Fe-Mn反铁磁偏置层。在这些器件中成功地观察到了自旋隧道自旋阀特性。

In this research, it is extremely important to develop the probe needle to detect spin polarization of electrons in the magnetic domains in magnetic materials, such as magnetic thin film media used in magnetic recording system especially in perpendicular magnetic recording system. These probe needle were fabricated using photo lithography technique. Firstly, substrates were coated with photoresist (OFPR) layrs and sputtered-Al films were deposited on it. Micro holes with its diameter around several mum were fabricated in the Al layrs by also photolithography technique. Photoresist under the hole were eliminated by the plasma ashing method using Oxygen mixture plasma. The probe will be formed when the sputtered particles through the hole are deposited on the substrate. We clarified that the relationship between aspect ratio, which defined as the diameter of the hole and the thickness of the photoresist layr, and the probe profiles by using Monte-Carlo simulation technique. Small aspect ratio resulted in the sharp profile of the deposited probe needles. Spin tunneling phenomena is one of the key point of this research, because the probe has to detect the spin polarization of the electrons which comes from the magnetic domains in the objective materials to the probe needle through an tunneling effect. In order to clarify the spin tunneling effect, spin valve devices composed of Ni-Fe/Si_3N_4/Ni-Fe sandwiched layrs with Fe-Mn antiferromagnetic bias layrs. It was succesfully observed the spin tunneling spin valve characteristic in these devices.