KENBIKYO Vol.48▶No.1 2013
■Feature Articles: Spin-Polarized Electron Technology

Development of Spin-Polarized and Pulsed Transmission Electron Microscope
―Based on the Fundamentals and the Advantage of Polarized Electron Source―

Makoto Kuwaharaa, Tsutomu Nakanishib, Yoshikazu Takedaa and Nobuo Tanakaa,c

aGraduate School of Engineering, Nagoya University
bGraduate School of Science, Nagoya University
cEcoTopia Science Institute, Nagoya University

Abstract: Spin-polarized electron beam is provided by a laser-driven electron gun using a semiconductor photocathode with a negative electron affinity surface. Nagoya University group of Prof. Nakanishi had realized a high polarization of 92 % with a quantum efficiency of 0.5 %, pico-second pulse beam, and a high reduced-brightness of 107 A/ by using the electron source. The R&D of polarized electron source is taken account of a complex of optical property of semiconductor, transport process in solid, surface physics and beam physics. In this paper, we describe the generation process of spin-polarized electron beam and the characteristics, and also mention a development of a novel transmission electron microscope (TEM) as an application research of the spin-polarized electron source. We have constructed a spin-polarized transmission electron microscope (SP-TEM) by mounting a polarized electron source on an ordinal TEM. TEM images and electron energy loss spectrum have been acquired in the SP-TEM. Moreover the energy spread of the spin-polarized electron beam is below 0.3 eV without any monochromater. In the end of this paper, we would like to mention about the first step of application and a future plan of the SP-TEM as a novel method of electron microscope.

Key words: Spin, Photocathode, Transmission Electron Microscopy, Pulse, Emittance