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In order to investigate the electronic properties of the semiconducting van der Waals ferromagnet Cr 2 Ge 2 Te 6 (CGT), where ferromagnetic layers are bonded through van der Waals forces, we have performed angle-resolved photoemission spectroscopy (ARPES) measurements and density-functional-theory (DFT+U) calculations. The valence-band maximum at the Γ point is located ~ 0.2 eV below the Fermi level, consistent with the semiconducting property of CGT. Comparison of the experimental density of states with the DFT calculation has suggested that Coulomb interaction between the Cr 3d electrons U eff ~ 1.1 eV. The DFT+U calculation indicates that magnetic coupling between Cr atoms within the layer is ferromagnetic if Coulomb U eff is smaller than 3.0 eV and that the inter-layer coupling is ferromagnetic below U eff ~ 1.0 eV. We therefore conclude that, for U eff deduced by the experiment, the intra-layer Cr-Cr coupling is ferromagnetic and the inter-layer coupling is near the boundary between ferromagnetic and antiferromagnetic, which means experimentally deduced U eff is consistent with theoretical ferromagnetic condition.

Polarization tunability and analysis of X-rays is one of the most advancing features of thirdgeneration synchrotron radiation sources. In order to apply such developments to the observation of magnetic effects, a diffractometer for X-ray magnetic absorption and scattering experiments was constructed on BL39XU at SPring-8. The ef®ciency of the apparatus is clearly demonstrated by several observations of the magnetic effects. In particular, a diamond phase plate plays an essential role in regulating both circular and linear polarization states.

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Bulk crystals of electron-doped cuprates with the T'-type structure require both Ce substitutions and reduction annealing for the emergence of superconductivity while the reduction annealing alone can induce superconductivity in thin films of the T'-type cuprates. In order to reveal low-energy electronic states which are responsible for the superconductivity, we have conducted angle-resolved photoemission spectroscopy measurements on thin films of the superconducting Ce-free T'-type cuprate Pr2CuO4. The results indicate that the overall band structure and the Fermi surface area of the superconducting Pr2CuO4 are similar to those of superconducting Ce-doped bulk single crystals, highlighting the importance of the actual electron concentration rather than the Ce concentration when discussing the physical properties of the T'-type cuprates.