Observation of three-dimensional bulk Fermi surfaces for a strongly   correlated material by soft x-ray $h\nu$-dependent (700-860 eV) ARPES
  Three-dimensional Fermi surfaces at a high temperature have been clarified for a strongly correlated Ce compound, ferromagnet CeRu$_2$Ge$_2$ in the paramagnetic phase, by virtue of a soft x-ray $h\nu$-dependent (700-860 eV) ARPES. Although the observed Fermi surfaces as well as quasiparticle dispersions are partly explained by a band-structure calculation based on a localized $4f$ model, qualitative discrepancy in experiments, between our APRES in the paramagnetic phase and de Haas-van Alphen measurement in the ferromagnetic phase, is revealed. This suggests a fundamental change in the $4f$ contribution to the Fermi surfaces across the magnetic phase transition widely seen for Ce compounds. 
M. Yano, A. Sekiyama, H. Fujiwara, T. Saita, S. Imada, T. Muro, Y.   Onuki, and S. Suga