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TT: Fachverband Tiefe Temperaturen

TT 17: SC: Fe-based Superconductors - 1111

TT 17.3: Vortrag

Montag, 14. März 2011, 18:45–19:00, HSZ 301

Gd³⁺ electron spin resonance spectroscopy on LaO_1−xF_xFeAs superconductors — •A. Alfonsov¹, F. Murányi², V. Kataev¹, N. Leps¹, R. Klingeler¹, A. Kondrat¹, C. Hess¹, S. Wurmehl¹, A. Köhler¹, G. Behr¹, and B. Büchner¹ — ¹IFW Dresden, D-01171 Dresden, Germany — ²Universität Zürich, CH-8057 Zürich, Schweiz

In this work we have studied by means of electron spin resonance (ESR) spectroscopy polycrystalline samples of LaO_1−xF_xFeAs (x = 0, 0.1) with small levels of Gd doping (2% and 5% with respect to La). The Gd³⁺ ion is an established spin probe to study local magnetic and charge environments in the crystal lattice. In the parent compound the Gd ESR signal is found to be sensitive to the magnetic phase transition from the paramagnetic to the spin density wave (SDW) state taking place at a temperature T_SDW∼ 130 K. Here, the analysis of the low-T ESR spectra gives evidence for the occurrence of magnetically non-equivalent Gd sites and possibly sites with different local charge environments. In the case of the superconducting samples with 10% of the F doping (T_c = 25 K) the Gd ESR gives no indication of the SDW order.