Extended Van Hove Singularity in a Noncuprate Layered Superconductor S<span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">r</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math></span>Ru<span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">O</mi></mrow><mrow><mn>4</mn></mrow></msub></mrow></math></span>

T. Yokoya; A. Chainani; T. Takahashi; H. Katayama-Yoshida; M. Kasai; Y. Tokura

doi:10.1103/PhysRevLett.76.3009

Extended Van Hove Singularity in a Noncuprate Layered Superconductor S $r_{2}$ Ru $O_{4}$

T. Yokoya, A. Chainani, T. Takahashi, H. Katayama-Yoshida, M. Kasai, and Y. Tokura

Phys. Rev. Lett. 76, 3009 – Published 15 April 1996

Abstract

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