Fermi surface topology of Ca_{1.5}Sr_{0.5}RuO_{4} determined by ARPES

TL;DR

This study uses ARPES to map the Fermi surface of Ca_{1.5}Sr_{0.5}RuO_{4}, revealing key topological differences from Sr_{2}RuO_{4} and providing insights into its electronic structure and correlation effects.

Contribution

First ARPES measurement of Ca_{1.5}Sr_{0.5}RuO_{4} Fermi surface topology, showing no orbital-selective Mott transition and highlighting differences from Sr_{2}RuO_{4}.

Findings

Gamma sheet is hole-like in Ca_{1.5}Sr_{0.5}RuO_{4}.

Fermi surface topology of alpha, beta sheets remains similar to Sr_{2}RuO_{4}.

Absence of orbital-selective Mott transition in Ca_{1.5}Sr_{0.5}RuO_{4}.

Abstract

We report ARPES results of the Fermi surface of Ca_{1.5}Sr_{0.5}RuO$_{4}, which is at the boundary of magnetic/orbital instability in the phase diagram of the Ca-substituted Sr ruthenates. Three t_{2g} energy bands and the corresponding Fermi surface sheets are observed, which are also present in the Ca-free Sr_{2}RuO$_{4}. We find that while the Fermi surface topology of the alpha, beta (d_{yz, zx}) sheets remains almost the same in these two materials, the gamma (d_{xy}) sheet exhibits a hole-like Fermi surface in Ca_{1.5}Sr_{0.5}RuO_{4} in contrast to being electron-like in Sr_{2}RuO_{4}. Our observation of all three volume conserving Fermi surface sheets clearly demonstrates the absence of orbital-selective Mott transition, which was proposed theoretically to explain the unusual transport and magnetic properties in Ca_{1.5}Sr_{0.5}RuO_{4}.