Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 19: Superconductivity: Poster Session

TT 19.19: Poster

Montag, 7. März 2016, 15:00–18:00, Poster D

Magnetism and Superconductivity in LaFeP_1−xAs_xO — •Sirko Kamusella¹, Rajib Sarkar¹, Hubertus Luetkens², Setsuko Tajima³, and Hans-Henning Klauss¹ — ¹Institut für Festkörperphysik, Technische Universität Dresden, 01062 Dresden, Germany — ²Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland — ³Department of Physics, Osaka University, Osaka 560-0043, Japan

The LaFeP_1−xAs_xO series bridges the gap between two parent compounds, whose Fermi surfaces differ in dimensionality and position of hole pockets. The resulting phase diagram consists of a superconducting two-dome structure separated by a novel AFM2 magnetic phase [1,2]. Electron doping by (O,F) substitution allows to investigate superconductivity in the full x-range.

⁵⁷Fe Mössbauer spectroscopy successfully depicts the temperature dependence of the tiny 0.1 µ_B magnetic moment in the AFM2 phase and its rigidity in applied field; with the help of a line width reference absorber. This uncommon approach makes Mössbauer measurements competitive to other local probe methods such as NMR or µSR.

µSR measurements can prove the long range character of this novel AFM2 phase and show the continuous change from a nodal to a nodeless symmetry of the superconducting order parameter upon substitution of P by As. AFM spin fluctuations suggested by NMR before [2] did not become evident in µSR decoupling experiments.