4f-Derived Fermi Surfaces ofCeRu2(Si1−xGex)2near the Quantum Critical Point: Resonant Soft-X-Ray ARPES Study

摘要: Angle-resolved photoelectron spectroscopy in the Ce $3d\ensuremath{\rightarrow}4f$ excitation region was measured for paramagnetic state of ${\mathrm{CeRu}}_{2}{\mathrm{Si}}_{2}$, ${\mathrm{CeRu}}_{2}({\mathrm{Si}}_{0.82}{\mathrm{Ge}}_{0.18}{)}_{2}$, and ${\mathrm{LaRu}}_{2}{\mathrm{Si}}_{2}$ to investigate changes $4f$ electron Fermi surfaces around quantum critical point. While difference between ${\mathrm{CeRu}}_{2}{\mathrm{Si}}_{2}$ experimentally confirmed, a strong $4f$-electron character observed band structures consequently indicating delocalized nature electrons both compounds. The absence surface reconstruction across composition suggests that SDW criticality is more appropriate than local ${\mathrm{CeRu}}_{2}({\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}{)}_{2}$.