バルク敏感角度分解光電子分光による固体 3 次元電子構造とフェルミ面の観測

抄録

  High-resolution and high-excitation energy photoemission spectroscopy has an advantage in probing the bulk electronic states in solids whereas the surface electronic states deviated from the bulk states are strongly reflected in low-excitation energy photoemission spectra which have so far extensively measured for many materials. We have succeeded in realization of the high-energy bulk-sensitive angle-resolved photoemission in order to probe the three-dimensional electronic structures and the Fermi surfaces. After introducing the angle-integrated photoemission spectra of 3d¹-electron system Sr_1-xCa_xVO₃ as an example for the bulk (surface) sensitivity of the high-(low-)energy photoemission, we show the recently obtained results of high-energy angle-resolved photoemission for strongly correlated electron systems such as Sr₂RuO₄ and ferromagnet CeRu₂Ge₂ in the paramagnetic phase, revealing their bulk Fermi surfaces. It is found that the Fermi surfaces of CeRu₂Ge₂ in the paramagnetic phase are substantially deviated from those in the ferromagnetic phase. Although our results for CeRu₂Ge₂ are roughly explained by the band-structure calculation for LaRu₂Ge₂, a few qualitative discrepancies are seen.