ISSP - The institute for Solid State Physics

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Komori Group

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Electronic and magnetic properties of low-dimensional and atomic-layer materials with nanometer-scale structures at solid surfaces are studied in an ultra-high vacuum using scanning tunneling microscopy/spectroscopy (STM/STS), photoelectron spectroscopy, magneto-optical Kerr-rotation and second harmonic generation measurements. Microscopic atomic, electronic and magnetic structures, formation processes of surface atomic-layers and dynamical processes induced by electron tunneling or photo-excited carriers are examined by local imaging, spectroscopy and quasi-particle interference observations using spin-resolved STM/STS, and macroscopic spin-dependent electronic structures, magnetic properties, electron dynamics and chemical bonds by photoelectron and optical spectroscopy using VUV light and soft-X-ray from laser and synchrotron.

(a-c) Topographic STM images of the graphene on thermally-decomposed vicinal SiC(0001) substrate (a) in Ar atmosphere. On the substrate surface, SiC (0001) terraces and macrofacets tilted 28 degrees off coexist. Magnified images of the terrace (b) and macrofacet (c) indicate formations of two- and one-dimensionally nano-periodic graphene on a part of the terrace and on the whole macrofacet, respectively. (d) Angle-resolved photoemission spectrum from the graphene on the macrofacet. Replica bands due to the periodic structure are seen. The doping level of the graphene is smaller than that on the terrace.
(a, b) Spin polarization direction of photoelectrons from spin split surface bands of Cu (111) and Ag (111) (a), and Bi (111) (b). The detected spin direction is in-plane and perpendicular to the momentum direction. For Cu (111) and Ag (111), it is the same as the spin polarization direction in the initial states. For Bi (111), when the polarization direction of the incident light is rotated by 90° from the p-polarized light to the s-polarized light, the spin polarization direction is inverted by 180°. (c) Dependence of the photoelectron spin components and total intensity of Bi (111) on the incident light polarization angle θ. The spin orientation of the photoelectrons changes three-dimensionally when θ is continuously changed. All these crystals are three dimensional topological materials.

Research Subjects

  1. Electronic states, magnetism and electron scattering of atomic layers and nano-structured materials at surfaces
  2. Formation processes of atomic layers and nano-structured materials at surfaces
  3. Electron and atom dynamics induced by electron tunneling and photo-excitation