Angle-resolved Photoemission Study of Ca$_{1.8}$Sr$_{0.2}$RuO$_{4}$

We report angle-resolved photoemission spectroscopy results of the Fermi surface of Ca$_{1.8}$Sr$_{0.2}$RuO$_{4}$ which is at the boundary between a magnetic metal and an antiferromagnetic insulator in the phase diagram of the Ca-substituted strontium ruthenates. We did observe an orbital-selective Mott transition, which is, however, different with what has been predicted theoretically [1] for this material. Our ARPES results are consistent with both magnetic and transport properties observed in this material. \newline [1] V. I. Anisimov et al., Eur. Phys. J. B \textbf{25}, 191(2002)