Dresden 2011 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 10: Poster Session: Superconductivity
TT 10.10: Poster
Montag, 14. März 2011, 14:00–18:00, P4
A quasi-optical setup for sub-terahertz ESR spectroscopy: application to superconducting iron pnictides — •R. Zahn1, A. Alfonsov1, G. Lang1, F. Lipps1, V. Kataev1, S. Aswartham1, S. Wurmehl1, J. S. Kim2, J. Deisenhofer3, H.-A. Krug von Nidda3, A. Loidl3, and B. Büchner1 — 1IFW Dresden, D-01069 Dresden, Germany — 2Pohang University of Science and Technology, Pohang, Korea — 3Center for Electronic Correlations and Magnetism, Augsburg University, D-86135 Augsburg, Germany
We present a high-sensitivity quasi-optical electron spin resonance (ESR) setup working in a frequency range of 250 - 800 GHz. Combination of optical means of propagation with a low-loss corrugated waveguide enables full control of the polarisation of the microwaves, which is essential for the high-sensitivity ESR measurements. The detection is realised by Millimeterwave Vector Network Analyzer. The setup is operational with a magneto-cryostat with a magnetic field up to 17 T and in a temperature range of 2 - 300 K. It enables to measure weak ESR signals not only from the insulating samples transparent for microwaves but also from metallic samples where the penetration of the microwaves is restricted by the skin depth. As an example of the application of this setup we show the temperature- and frequency-dependent ESR measurements on small single crystals of (Eu,Ba)(Fe,Co)2As2 superconductor. We find that the Eu2+ ESR is sensitive to the structural and magnetic phase transitions occurring in this material. We discuss the interaction between the Eu- and Fe-subsystems and its relevance for the understanding of the properties of these novel superconductors.