Depth dependence of itinerant character in Mn-substituted Sr3Ru2O7

We present a core-level photoemission study of Sr3(Ru1?xMnx)2O7, in which we monitor the evolution of the Ru-3d fine structure versus Mn substitution and probing depth. In both Ru-3d3/2 and -3d5/2 core levels, we observe a clear suppression of the metallic features, i.e. the screened peaks, implying a sharp transition from itinerant to localized character already at low Mn concentrations. A comparison of soft and hard x-ray photoemission, which enables tunable depth sensitivity, reveals that the degree of localized/metallic character for Ru at the surface is different from that in the bulk.