Dresden 2009 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 5: Postersession Superconductivity: Materials - Fabrication and Properties

TT 5.33: Poster

Monday, March 23, 2009, 13:00–16:45, P1A

Electronic phase separation and magnetic order in the cobalt doped RFe_2−xCo_xAs₂ (R=Sr, Eu) iron pnictide superconductors — A. Kwadrin¹, H. Maeter¹, H.-H. Klauss¹, H. Luetkens², R. Khasanov², A. Amato², •M. Kraken³, J. Litterst³, A. Jesche⁴, A. Leite-Jasper⁴, H. Rosner⁴, W. Schnelle⁴, and C. Geibel⁴ — ¹Institut für Festkörperphysik, TU Dresden — ²Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen, Switzerland — ³Institut für Physik der Kondensierten Materie, TU Braunschweig — ⁴Max-Planck-Institut für Chemische Physik fester Stoffe Dresden

We have investigated the magnetic and superconducting properties of RFe_2−xCo_xAs₂ with R=Sr, Eu and 0≤x≤0.4 by means of muon spin relaxation (µ⁺SR) and Mössbauer spectroscopy. Under ambient pressure the antiferromagntic ordering temperature, T_N of SrFe_2−xCo_xAs₂ decreases with increasing Co-doping. However, T_N remains finite even as superconductivity appears as a function of doping. This shows that electronic phase separation plays a role in this system. High pressure experiments show a reduction the magnetic ordering temperature by pressure. On the contrary, EuFe_2−xCo_xAs₂ does not show superconductivity under ambient pressure but a peculiar interplay of the rare earth and iron magnetic order as a function of the Co-doping level.