Development of spin-polarized transmission electron microscope
Development of spin-polarized transmission electron microscope
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DOI：
10.1088/1742-6596/298/1/012016
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发表时间：
2011-05
期刊：
影响因子：
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通讯作者：
M. Kuwahara;Y. Takeda;K. Saitoh;T. Ujihara;H. Asano;T. Nakanishi;N. Tanaka
中科院分区：
文献类型：
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作者：
M. Kuwahara;Y. Takeda;K. Saitoh;T. Ujihara;H. Asano;T. Nakanishi;N. Tanaka
为了研究纳米材料中的自旋相关现象，在透射电子显微镜（TEM）中采用自旋极化电子源（PES）作为入射光束。设计并构建了适用于自旋极化TEM的PES系统。TEM的照明系统也被设计成聚焦从具有负电子亲和势（NEA）表面的半导体光电阴极发射的自旋极化电子束。电子束能量被设置为低于40 keV，这是TEM的较低能量类型，因为与凝聚态物质的自旋相互作用非常小，对应于库仑相互作用。该极化电子枪在超高真空条件下实现，阴极表面场梯度为4 MV/m。此外，它表明，40-keV的极化电子束操作与亚毫秒脉冲模式，通过使用背面激发型光阴极。这种高性能的PES将使TEM动态观察高对比度的磁场图像和高速的时间成像成为可能。
In order to study spin related phenomena in nano-size materials, spin-polarized electron source (PES) has been employed for the incident beam in transmission electron microscope (TEM). The PES has been designed and constructed with optimizing for spin-polarized TEM. The illuminating system of TEM is also designed to focus the spin-polarized electron beam emitted from a semiconductor photocathode with a negative electron affinity (NEA) surface. The beam energy is set to below 40 keV which is lower energy type as a TEM, because the spin interaction with condensed matters is very small corresponding with a Coulomb interaction. The polarized electron gun has realized in an extra high vacuum (XHV) condition and high field gradient of 4 MV/m on a surface of photocathode. Furthermore, it demonstrated that 40-keV polarized electron beam was operated with a sub-milli second pulse mode by using the backside excitation type photocathode. This high performance PES will make it possible to observe dynamically a magnetic field images with high contrast and highspeed temporal imaging in TEM.