SONDERSEMINAR: Prospect of Photoelectron Momentum Microscopy(PMM) and Sot X-ray Resonant Inelastic Scattering(SX-RIXS) down to µm scale and Spin-Resolved Measurements as well as measurements under external perturbations

  • Tagungsort:

    Seminarraum 6-1, Geb. 30.23
    (gleichzeitig via Zoom, Details: sekretariat@phi.kit.edu)

  • Datum:

    Montag, 01.07.2024, 16.00 Uhr

  • Referent:

    Prof. Shigemasa Suga
    Sanken, Osaka University, Japan

  • Angle resolve photoelectron spectroscopy(ARPES) is a very powerful approach to clarify the electronic structures of conductive materials. However, the sample rotation was usually employed to cover the wide (kx,ky) region. Then the selection rules changes and often the probed regions on the surface changed also. The low detection efficiency of the conventional ARPES also induced the surface radiation damages, spoiling the qua- lity of the obtained results.

    To solve these problems, photoelectron momentum microscope(PMM)was developed in early 2010th. When I met with this approach in the Kirschner’s Lab in Max-Planck-Institute for Microstructure Physics, Halle in 2013, I recognized its high potential. By the high extraction voltage between the sample surface and the PEEM type objective lens up 15 or 20 kV, the whole photoelectrons emitted into 2ϖ steradian can be simultaneously recorded by the 2D detector in the case of Ek up to ~70eV. Then the ARPES efficiency becomes orders of magnitude higher by PMM than the conventional ARPES.

    In addition, effective spin detection is feasible by use of 2D spin filter at low electron kinetic energy (10.25 and 11.5eV) with FoM of around 102. Then the spin detection efficiency becomes around 5 million times higher than the Fe-O VLEED single channel detection.

    Since we have installed the PMM at UVSOR BL6U+BL7U we can now perform EB(x,y,z)(kx,ky,kz) PMM not only at 68° incidence but also normal incidence for the 1st time in the world. The selection rule dependence of the EB(kx,ky,kz) is now measurable and theoretically anlyzable. Within this year, we will install a Au/Ir(001) spin filter and start SP-PMM in UVSOR, Okazaki, Japan. The sub-µm resolution without any sample move- ment and radiation damage will provide us useful and reliable information for device development. We will soon start measurements of magnetized samples as well as samples under electric field and uniaxial strain. On the other hand, non-conductive materials should be studied by other method. Soft X-ray resonant inelastic scattering (SX-RIXS) combined with theoretical analyses can provide rich information on electronic states. Operando measurement is feasible under the magnetic field, electric field as well as under a uniaxial strain. Since this technique is bulk sensitive, the focusing of the soft X-ray smaller than 1µm facilitates the reliable measurement.

    By combining these techniques and spin-STM/STS, we would like to study electronic states of operand device in the µm scale to develop new devices for the fruitful future of human beings.

     

    1. Photoelectron Spectroscopy: Bulk & Surface Electron Structures. Springer Series in Surface Sciences 72, 1-511. 2nd edition(2021). S.Suga, A.Sekiyama and C.Tusche.