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TT: Fachverband Tiefe Temperaturen

TT 23: Superconductivity: Fe-based Superconductors - 1111

TT 23.2: Talk

Monday, March 11, 2013, 17:00–17:15, H21

Phase diagram of F- and Co-doped CeFeAsO — •Oleksii Vakaliuk, Sabine Wurmehl, Christine Malbrich, Eva Brüning, Hans-Joachim Grafe, Christian Hess, and Bernd Büchner — Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstr. 20, 01069 Dresden Germany

We carried out an experimental systematic electronic resistivity investigation of CeFeAsO system in a wide Co-doping range (0 - 0.12) and compare it to F-doped (0 - 0.10) CeFeAsO. The resistivity of the pristine compound: i) exhibits a pronounced peak at approximately 150 K, followed by a steep decrease and ii) an inflection point which are clear signatures of the tetragonal to orthorhombic structural transition, and the antiferromagnetic spin density wave transition, respectively. iii) At low temperature the resistivity shows a kink-like anomaly due to ordering of Ce magnetic moments. Upon doping these anomalies shifts to lower temperature, and become suppressed and broadened. From these observations we construct the magnetic/superconducting phase diagrams for both compounds. Furthermore, NMR/NQR studies reveal a new type of microscopic order in the underdoped normal state regime.