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TT: Fachverband Tiefe Temperaturen

TT 10: Poster Session: Superconductivity

TT 10.39: Poster

Monday, March 14, 2011, 14:00–18:00, P4

Surface and bulk electronic structure of Sr₂RuO₄ — •Volodymyr Zabolotnyy¹, Emanuela Carleschi², Timur Kim¹, Alexander Kordyuk¹, Jan Thöne¹, Johen Geck¹, Daniil Evtushinsky¹, Bryan Doyle², Rosalba Fittipaldi³, Mario Cuoco³, Antonio Vecchione³, Bernd Büchner¹, and Sergey Borisenko¹ — ¹IFW - Dresden, Germany — ²University of Johannesburg, South Africa — ³CNR-INFM SuperMat Regional Laboratory, University of Salerno, Italy

Strontium ruthenates are famous for p-type superconductivity, metamagnetism, and notable spin-orbit coupling. Understanding all these phenomena requires a detailed knowledge of the electronic structure. Unfortunately recent ARPES on Sr₂RuO₄ was confronted with a problem of an acute ‘surface state’ (SS). Here we argue that, instead of the earlier proposed remedy of high temperature cleaving, one may rely on excitation energy dependence of matrix elements enhancing surface or bulk features, while circularly polarized light can be used to establish their origin. Owing to the minimized surface degradation we observe bulk α, β, γ bands and their surface counterparts along with additional δ feature. According to the dichroic pattern the new feature must be yet another surface counterpart of the β band. Also the narrower momentum width together with negligible k_z dispersion are distinct properties specific to a surface state. Since there are numerous examples where the surface state undergoes splitting due to spin-orbit interaction we suggest that full relativistic calculation might be needed to understand the origin of the new feature.