Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 39: SC: Iron-Based Superconductors - 1111
TT 39.9: Vortrag
Freitag, 26. März 2010, 12:30–12:45, H19
Superconductivity and Ferromagnetism in CeFeAs1−xPxO — •Anton Jesche, Cornelius Krellner, and Christoph Geibel — Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
The emergence of superconductivity in RFeAsO (R = rare earth) is connected with the suppression of the antiferromagnetic (AFM) ordering of Fe which can be achieved by the substitution of e.g. La by Sr, Fe by Co, As by P, and O by F. A special case here is CeFeAs1−xPxO, which shows AFM ordering of Fe at TNFe = 145 K and AFM ordering of Ce at TNCe = 3.7 K for pure CeFeAsO, whereas pure CeFePO is a paramagnetic heavy fermion metal. The substitution of As by P results in a decrease of TNFe similar to F doping. An extrapolation suggests a complete suppression of the Fe ordering for x ≃ 0.35. However, instead of the expected’ superconducitivity, the Ce ordering changes from AFM to FM at the disappearance of TNFe and superconductivity emerges only in a small concentration range around x = 0.3. We report on measurements of electrical resistivity, specific heat, and magnetic susceptibility on single- and polycrystalline samples. Our results are supported by NMR, ESR, and µSR measurements and reveal a competition of superconductivity and ferromagnetic ordering of Ce.