Orbital-selective metal-insulator transition and gap formation above Tc in superconducting Rb1-xFe2-ySe2

Zhe Wang; M. Schmidt; J. Fischer; V. Tsurkan; M. Greger; D. Vollhardt; A. Loidl; J. Deisenhofer

doi:10.1038/ncomms4202

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arXiv · 1309.6084

Orbital-selective metal-insulator transition and gap formation above Tc in superconducting Rb1-xFe2-ySe2

Zhe Wang·M. Schmidt·J. Fischer·V. Tsurkan·M. Greger·D. Vollhardt·A. Loidl·J. Deisenhofer

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Abstract

We report on a hierarchy of temperatures Tc < Tgap < Tmet in superconducting Rb1-xFe2-ySe2 observed by THz spectroscopy. Above Tmet = 90 K the material reveals semiconducting characteristics. Below Tmet a coherent metallic THz response emerges. This metal-to-insulator type, orbital selective transition is clearly indicated by an isosbestic point in the temperature dependence of the optical conductivity and dielectric constant at THz-frequencies. At Tgap = 61 K a gap opens in the THz regime and then the superconducting transition occurs at Tc = 32 K. This sequence of temperatures seems to reflect a corresponding hierarchy of the electronic correlations in the different bands.

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Zhe Wang, M. Schmidt, J. Fischer, V. Tsurkan, M. Greger, D. Vollhardt, A. Loidl, J. Deisenhofer. 2013-09-24. Orbital-selective metal-insulator transition and gap formation above Tc in superconducting Rb1-xFe2-ySe2. https://doi.org/10.1038/ncomms4202

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