To promote the discussion among the scientists in the surface science and synchrotron radiation science, we annually hold Joint Conference of Nanospectropy Division in SPring-8 Users Community, Synchrotron Radiation and Probe Microscopy Divisions in the Japan Society of Vacuum and Surface Science. In this special issue, we feature four distinguished topics presented in the joint conference held online on March, 2021 (Nanospec2021).

Spintronics, which utilizes spin and charge degrees of freedom, has produced a variety of devices such as non-volatile magnetic memory and microwave oscillators. In this paper, we report the results of a comprehensive approach to the analysis of structure, charge, and spin of spintronic materials and devices using a wide range of advanced synchrotron radiation tools, including magnetic Compton analysis, nuclear resonant scattering analysis, surface and interface X-ray diffraction, operando nanoelectronic structure analysis, and photoemission spectroscopy.

Angle-resolved photoemission spectromicroscopy with submicron resolution (nano-ARPES) is a powerful technique to study electronic structure of microcrystals and microdomains. Transition-metal compounds such as FeTe and IrTe₂ exhibit unique phase transitions due to orbital symmetry breaking (orbital order). In nano-ARPES studies on FeTe and IrTe₂ surface, we observed interesting domain textures which would be related to their microscopic orbital orders. The antiferromagnetic phase of FeTe hosts stripe-type domains driven by its anisotropic electronic state. In case of IrTe₂, each domain harbors quasi one-dimensional surface bands forming fragmented Fermi surfaces (Fermi arcs). The nano-ARPES measurement enabled us to identify the unique domain dependent surface states in the orbital ordered phase of IrTe₂.

We developed regulated metal structures on supports for heterogeneous catalysis by the attachment and subsequent structural transformations of metal complexes on support surfaces such as metal oxides and carbon supports. Unique metal structures are sometimes different from original structures in solutions, and they are attractive in that they show unique catalytic performances which are often derived from cooperative behaviors of metal-metal and/or metal-support interactions, and provide new insights for heterogeneous catalysis. Synchrotron radiation X-ray analyses such as XAFS and XPS are one of the useful methods not only to characterize metal coordination structures on the surface but also to clarify the formation mechanism and the role at the redox/catalytic reaction under operation conditions. In this paper, we highlight our achievements on the development of supported metal complex, metal nanoparticle, and metal oxide catalysts in which synchrotron radiation X-ray analyses played important roles.

We present a first-principles method based on density functional theory (DFT) to calculate the absolute binding energy of core electrons with high accuracy. The method is based on DFT for the constrained “ground state” based on the Gunnarsson-Lundqvist (GL) theorem, and introduces the penalty functional method and the exact Coulomb cutoff method to perform the calculation of the final state. The average absolute error for 26 cases of solids and molecules is 0.42 eV and the relative error is 0.17%. We present applications to silicene and borophene, and show that the results can be directly compared with the binding energies obtained by X-ray photoelectron spectroscopy.