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Department of Physics & Astronomy

Pushing the limits of laser-based photoemission for materials science

2017-11-01l 조회수 945
일시 : 2017-11-01 16:00 ~
연사 : Shik Shin (University of Tokyo)
담당 :
장소 : 56동106호
Angle resolved photoemission spectroscopy (ARPES) is very powerful to know the solid-state properties, because one can know the solid state electrons directly. ARPES has been studied by synchrotron radiation or noble-gas-discharge lamp. Recently, ultraviolet(UV)- and soft-X-ray(SX)-lasers have been developed very rapidly, and it is found that they are very powerful for the photoemission spectroscopy as the new light source. Laser has excellent properties, such as coherence, monochromaticity, polarization, ultra-short pulse, very high intensity, and so on. Each excellent property of laser will give us the fruitful results to see the deep insights into the various nature of the materials. I would like to introduce laser-photoemission is very powerful for the materials science, such as high resolution ARPES [1,2], spin-resolved ARPES [3], time-resolved ARPES [4], and photoemission microscopy (PEEM) [5], as shown by the Fig.1. At present, low-temperature high-resolution laser-ARPES system has achieved the highest energy resolution of about 70 μeV and the lowest sample temperature of 1.0 K, by using ultra-high-resolution-quasi-CW laser in UV region. High resolution ARPES has been found to be very powerful for the study of superconductors to know their mechanism. Spin-resolved laser-ARPES has also reached the resolution of about 1meV and useful for the study of the spin texture in the materials. On the other hand, high resolution laser-PEEM has the spatial resolution of 2.6 nm using CW laser in UV region and powerful for the study of the magnetic nanostructures. Furthermore, femto-second time-resolved ARPES becomes possible in UV and SX-region, by using the newly-developed-higher-harmonics laser system. Based on these recent experimental results, I would like to introduce the present status and future prospects of various laser photoemission spectroscopy.
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