Development of a nanometer scale spin polarized scanning electron microscope for surface magnetism

开发用于表面磁性的纳米级自旋偏振扫描电子显微镜

• 批准号: 11440113
• 负责人: MIZUNO Seigi
• 金额: $ 9.09万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11440113/
• 关键词: electron spin; surface magnetism; field emission; scanning tunneling microscopy; low energy electron diffraction; spin polarized SEM; Mott detector; secondary electrons

The goal of this research is to develop an apparatus for measurement of surface magnetism at nanometer-scale spatial resolution. The instrument consists of a scanning tunneling microscopy (STM) tip as a field emission gun, and a Mott detector for measuring the electron spin polarization.The following results have been obtained. (1) The operation of the tips under a field emission condition with bias voltages of 14 - 50 V has been established. The emission current was stable in the region from 0.1 nA to 1 nA. (2) The distances between the tip and the sample were measured while the bias voltage was changed, under a constant current mode. The results show that the distances strongly depend on the shape of the tip apex. A sharp tip apex is necessary to detect the scattered electrons. (3) The operation of the tips under a field emission condition with bias voltages of 14 - 50 V made it possible to detect the scattered electrons using a micro-channel plate. (4) A tip-shield has been proposed … More to improve extraction functions. The influence of the tip-shield was calculated using a simulation program and confirmed experimentally. The detection efficiency of the scattered electrons became remarkably large. (5) The possibility of nanometer-scale low-energy electron diffraction using STM tips has been demonstrated. (6) It has been confirmed that the tip-shield exerts no harmful influences on the resolution of the STM measurements. Atomic resolution has been achieved with the tip-shield on Si(111) and Si(001) surfaces. (7) A small-size Mott detector of good sensitivity has been developed using a fluorescent material.The full development of the apparatus has not been completed because the amount of scattered electrons is very low. Moreover, the field emission condition depends very strongly on the shape of the tip apex. However, the above results show the path for the development of the target instrument, and demonstrate a potential for the detection of the surface electron spin polarization at nanometer-scale resolution. Less

本研究的目的是研制一种纳米尺度空间分辨率的表面磁性测量装置。该仪器由作为场发射枪的扫描隧道显微镜(STM)针尖和用于测量电子自旋极化的Mott探测器组成。(1)在偏置电压为14-50V的场致发射条件下，建立了针尖的工作状态。发射电流在0.1nA~1nA范围内稳定。(2)在恒流模式下，改变偏置电压，测量针尖与样品之间的距离。结果表明，距离与尖端的形状有很强的相关性。为了探测到散射的电子，尖端的尖端是必要的。(3)在偏置电压为14-50V的场致发射条件下，针尖的工作使利用微通道板探测散射电子成为可能。(4)提出了一种尖端屏蔽方案(…更多的是为了提高提取功能。利用模拟程序对尖端屏蔽的影响进行了计算，并进行了实验验证。散射电子的探测效率变得非常大。(5)论证了利用STM针尖进行纳米级低能电子衍射的可能性。(6)证实了尖端屏蔽对STM测量的分辨率没有不良影响。利用在Si(111)和Si(001)表面上的尖端屏蔽，实现了原子分辨率。(7)利用荧光材料研制了灵敏度高的小尺寸Mott探测器，但由于散射电子量很低，该装置尚未完全研制完成。此外，场发射条件强烈地依赖于尖端尖端的形状。然而，上述结果为目标仪器的发展指明了道路，并展示了在纳米级分辨率下检测表面电子自旋极化的潜力。较少

项目成果

S. Mizuno, J. Fukuda and H. Tochihara: "Extraction of scattered low-energy electrons in field emission conditions"Surface Science. (in press). (2002)

S. Mizuno、J. Fukuda 和 H. Tochihara：“场发射条件下散射低能电子的提取”表面科学。

S.Mizuno: "Development of an advanced low-energy electron diffraction technique using field-emitted electrons from STM tips"J.Vacuum Science and Technology B. 19. 1874-1878 (2001)

S.Mizuno：“利用 STM 尖端的场发射电子开发先进的低能电子衍射技术”J.Vacuum Science and Technology B. 19. 1874-1878 (2001)

S.Mizuno, J.Fukuda, H.Tochihara: "Extraction of scattered low-energy electrons in field emission condition"Surface Science. (in press). (2002)

S.Mizuno、J.Fukuda、H.Tochihara：“场发射条件下散射低能电子的提取”表面科学。

S.Mizuno: "Development of an advanced low-enregy electron diffraction technique using field-emitted electrons from STM tips"Journal of Vacuum Science and Technology B. 19. 1874-1878 (2001)

S.Mizuno：“利用 STM 尖端的场发射电子开发先进的低能电子衍射技术”Journal of Vacuum Science and Technology B.19. 1874-1878 (2001)

S. Mizuno: "Development of an advanced low-energy electron diffraction technique using field-emitted electrons from STM tips"Journal of Vacuum Science and Technology B. 19. 1874-1878 (2001)

S. Mizuno：“利用 STM 尖端的场发射电子开发先进的低能电子衍射技术”真空科学与技术杂志 B. 19. 1874-1878 (2001)