EXTENDED VAN-HOVE SINGULARITY IN SR2RUO4 OBSERVED BY ANGLE-RESOLVED PHOTOEMISSION

We have performed low-temperature high-resolution angle-resolved photo emission spectroscopy on a non-cuprate superconductor Sr2RuO4 (T-c sim ilar to 1 K) which has the same crystal structure as La2CuO4 but with RuO2 layers replacing CuO2. We found that Sr2RuO4 has an extended van- Hove singularity (VHS) close to E(F)(20+/-2 meV) like high-T-c cuprate s, regardless of the character of the electronic states at E(F), sugge sting that the extended VHS is a general feature of a two-dimensional d-electron metal. This demands re-examination of the VHS scenario for the superconducting properties of cuprates, while T-linear resistivity seems to be consistent with this result.