Surface electronic structure of ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$

We have addressed the possibility of surface ferromagnetism in ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$ by investigating its surface electronic states by angle-resolved photoemission spectroscopy (ARPES). By cleaving samples under different conditions and using various photon energies, we have isolated the surface from the bulk states. A comparison with band structure calculations indicates that the ARPES data are most readily explained by a nonmagnetic $\sqrt{2}\times \sqrt{2}$ surface reconstruction.