Development of method of high resolution magnetic imaging by spin polarized scanning tunneling microscope

为了研究高分辨率表面的磁性，我们研制了自旋极化扫描隧道显微镜(SP-STM)。首先，我们制作了一个超高真空(UHV)系统，它由分析室和制备室组成，分析室配备了最大磁场为8KoE的电磁铁，STM和低电子能量衍射和俄歇电子能谱(LEED/AES)系统。超高压系统由机械旋转泵、涡轮分子泵、离子泵和钛升华泵抽真空，在150度的温度下烘烤后，真空压力达到1x10^&lt；-8&gt；0pa。扫描隧道显微镜由管状压电陶瓷扫描器、用于航向接近的压电电机、用于减振的线圈弹簧、样品支架和用于测量隧道电流的前置放大器组成。ASTM的刀尖是用摇杆交换的。四个STM尖端和两个样品储存在分析室内的传送带中。研制了一种采用数字控制方法的STM控制器。前置放大器转换针尖和样品之间的隧道电流，并通过16位AD转换器读取所获得的电压，用于数字反馈以控制样品的针尖位置。扫描是通过在压电扫描器的X和Y电极上施加三角电压来实现的。为了测量自旋极化信息，使用岩石输入放大器来检测隧道电流的交流分量。为了制备用于SP-STM测量的磁性纳米结构样品，在坡莫合金Ni_&lt；80&gt；Fe_&lt；20&gt；薄膜上进行了AFM阳极氧化。在本研究中，我们开发了SP-STM。此后，我们将使用该测量系统来获取纳米尺度的表面磁性信息。

We developed spin polarized scanning tunneling microscope (SP-STM) in order to investigate magnetic properties on surfaces with high resolution. First, we fabricated an ultra-high vacuum (UHV) system that consists of an analysis chamber and a preparation chamber; the analysis chamber equips an electromagnet with maximum magnetic field of 8 kOe, the STM and a low electron energy diffraction and auger electron spectroscopy (LEED/AES) system. The UHV system is evacuated by mechanical rotary pump, turbo molecular pump, ion pump and titanium sublimation pump; after baking this chamber at temperature of 150 degrees, vacuum pressure of lx10^<-8>0 Pa was obtained. The STM consists of a scanner of a tube piezo ceramics, a piezo motor for course approach, coil springs for anti-vibration, a sample holder and a pre-amplifier for measurement of tunneling current. ASTM tip is exchanged by using a wobble stick. Four STM tips and two samples are stored in a carousel inside the analysis chamber. We developed an STM controller with digital control method. A tunneling current flowing between tip and sample is converted by the pre-amplifier, and the obtained voltage is read by 16 bits AD converter, which is used for digital feedback to control the tip position from the sample. Scanning was achieved by applying triangular voltages to X and Y electrodes of the piezo scanner. For measuring spin polarized information, a rock in amplifier was used to detect AC components of the tunneling current. In order to fabricate sample of magnetic nano-structure for SP-STM measurements, fabrication by AFM anodization was performed on the permalloy Ni_<80>Fe_<20> thin film. In this study we developed the SP-STM. Hereafter, we will use this measurement system to obtain the surface magnetic information in nano-scale.