We have performed high-resolution angle-resolved photoemission spectroscopy on single crystal Sr2RuO4. at low temperature. We observed that the dispersion of energy bands near the Fermi level (EF) is about two times smaller than the band calculation. One band forms an extended van-Hove singularity (vHs) near EF around the midpoint between F and Z point like in cuprate superconductors, regardless of the character of electronic states near EF. The observed Fermi surface topology (one electron-like Fermi surface sheet centered at Γ point and two hole-like ones centered at X point) is qualitatively different from the calculated Fermi surface topology (two electron-like fermi sheets centered at Γ point and one hole-like one centered at X point), though the observed total electron count seems to be conserved. These results suggest that the extended vHs may be a general electronic structure of correlated two-dimensional metals and the correlation effect may change the Fermi surface topology as well as the band dispersion.
- Angle-resolved photoemission spectroscopy
- Extended Van Hove singularity
- Fermi surface topology
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering