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

Makoto Kuwahara^a, Tsutomu Nakanishi^b, Yoshikazu Takeda^a and Nobuo Tanaka^a,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/m².sr.V 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