Dresden 2011 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 10: Poster Session: Superconductivity
TT 10.14: Poster
Monday, March 14, 2011, 14:00–18:00, P4
Optical Investigations on the Effect of Phosphorous Substitution in EuFe2(As1−xPx)2 Single Crystals — •Sina Zapf1, Geoffrey Chanda1, Dan Wu1, Hirale S. Jeevan2, Philipp Gegenwart2, and Martin Dressel1 — 11. Physikalisches Institut, Universität Stuttgart, Germany — 2I. Physikalisches Institut, Universität Göttingen, Germany
The ab-plane optical, magnetic and transport properties of EuFe2(As0.88P0.12)2 single crystals have been investigated and were compared to those of EuFe2As2 (TSDW=189 K) and the superconducting EuFe2(As0.82P0.18)2 (Tc=28 K). We identify in the case of x=0.12 a spin density wave (SDW) transition below 110 K.
Isovalent P substitution on the As site depresses the SDW in EuFe2As2. For x=0.18, the SDW has already disappeared. The resistivity curve of our x=0.12 sample shows an anomaly below 110 K with a different shape compared to the SDW feature of the parent compound. However, the Drude-Lorentz analysis on the optical conductivity spectra indicates a SDW gap formation similar to EuFe2As2. We observe a drop in reflectivity between 170 and 1200 cm−1 as well as the transfer of the spectral weight up to 3500 cm−1. The latter effect can be understood as a many-body (interband) interaction in the multiband system. The magnetic ordering of the Eu2+ spins and thus the interplay between magnetism and superconductivity are examined by susceptibility measurements. We found a similar ordering as in the parent compound with a decrease of TN down to 16.5 K.