XPS and ARPES study of the metal-insulator transition in Mn-substituted Sr$_3$Ru$_2$O$_7$

We have studied the metal-insulator transition in Mn-substituted Sr$_3$Ru$_2$O$_7$ by core-level x-ray photoemission (XPS) and angle-resolved photoemission spectroscopy (ARPES). In XPS, both the surface- and bulk-sensitive spectra show a two-peak structure, corresponding to the well screened and the unscreened excitations. The intensity of the well-screened peak is suppressed upon increasing the concentration of Mn, reflecting a metal-to-insulator transition induced by Mn impurities. In ARPES, changes in Fermi surface topology and band dispersions are observed as the system crosses over from a metal to a - possibly Mott - insulator. We observed a variation and enhancement of the Fermi-surface nesting upon Mn substitution, which might be connected to the emergence of the magnetic superstructure revealed by our resonant elastic soft x-ray scattering results [1].\\[4pt] [1] M.A. Hossain {\it et al.}, arXiv:0906.0035 (2009).