Extended Van Hove singularity in a noncuprate layered superconductor Sr2RuO4.

摘要: Angle-resolved photoemission spectroscopy was performed on a ruthenate superconductor S${\mathrm{r}}_{2}$Ru${\mathrm{O}}_{4}$ ( ${T}_{c}\ensuremath{\sim}1$ K) which has the same crystal structure as L${\mathrm{a}}_{2}$Cu${\mathrm{O}}_{4}$, but with Ru${\mathrm{O}}_{2}$ layers replacing Cu${\mathrm{O}}_{2}$ layers. shows an extended Van Hove singularity (VHS) at $20\ifmmode\pm\else\textpm\fi{}2$ meV below ${E}_{F}$ just like cuprates, regardless of character electronic states ${E}_{F}$. This suggests that VHS is general feature two-dimensional correlated d-electron metal. The observed Fermi surface in contrast to local-density-approximation calculations.