Dresden 2014 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 45: Superconductivity: Fe-based Superconductors - 1111,111, FeSe
TT 45.8: Talk
Tuesday, April 1, 2014, 15:45–16:00, HSZ 201
Orbital-selective metal-insulator transition and gap formation above Tc in superconducting Rb1−x Fe2−ySe2 — •Zhe Wang1, Michael Schmidt1, Jonas Fischer1, Vladimir Tsurkan1, Markus Greger2, Dieter Vollhardt2, Alois Loidl1, and Joachim Deisenhofer1 — 1Experimentalphysics 5, Univ. Augsburg, Germany — 2Theoreticalphysics 3, Univ. Augsburg, Germany
We report on a hierarchy of temperatures Tc < Tgap < Tmet in superconducting Rb1−x Fe2−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 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.