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ST171 - Electromagnetic Response of LaO0.94F0.06FeAs: AC Susceptibility and Microwave Surface Resistance

Electromagnetic Response of LaO0.94F0.06FeAs: AC Susceptibility and Microwave Surface Resistance

A. Agliolo Gallitto1, G. Bonsignore1, M. Bonura1,
M. Li Vigni1, J. L. Luo2 and A. F. Shevchun3

1CNISM and Dipartimento di Scienze Fisiche ed Astronomiche,
Universit´a di Palermo, Via Archirafi 36, I-90123 Palermo, Italy
2Beijing National Laboratory for Condensed Matter Physics,
Institute of Physics, Chinese Academy of Sciences,
Beijing 100190, China
3Institute of Solid State Physics, Russian Academy of Sciences,
Chernogolovka, Moscow District

E-mail: [email protected]

ABSTRACT - We discuss on the electromagnetic response of a polycrystalline sample of Electromagnetic response of LaO0.94F0.06FeAs exposed to DC magnetic fields up to 10 kOe. The low-and high-frequency responses have been investigated by measuring the AC susceptibility at 100 kHz and the microwave surface resistance at 9.6 GHz. At low as well as high DC magnetic fields, the susceptibility strongly depends on the amplitude of the AC driving field, highlighting enhanced nonlinear effects. The field dependence of the AC susceptibility exhibits a magnetic hysteresis that can be justified considering the intragrain-field-penetration effects on the intergrain critical current density. The microwave surface resistance exhibits a clockwise magnetic hysteresis, which cannot be justified in the framework of the critical-state models of the Abrikosov-fluxon lattice; it may have the same origin as that detected in the susceptibility.

IEEE/CSC & ESAS EUROPEAN SUPERCONDUCTIVITY NEWS FORUM (ESNF), No. 11, January 2010
Published in Journal of Physics Conf. Series (SuST234, 012001 (2010)