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arXiv · 1001.1302

Magnetic fluctuations and superconductivity in Fe pnictides probed by electron spin resonance

N. Pascher·J. Deisenhofer·H. -A. Krug von Nidda·M. Hemmida·H. S. Jeevan·P. Gegenwart·A. Loidl
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Abstract

The electron spin resonance absorption spectrum of Eu^{2+} ions serves as a probe of the normal and superconducting state in Eu_{0.5}K_{0.5}Fe_2As_2. The spin-lattice relaxation rate 1/T_1^{\rm ESR} obtained from the ESR linewidth exhibits a Korringa-like linear increase with temperature above T_C evidencing a normal Fermi-liquid behavior. Below 45 K deviations from the Korringa-law occur which are ascribed to enhanced magnetic fluctuations within the FeAs layers upon approaching the superconducting transition. Below T_C the spin-lattice relaxation rate 1/T_1^{\rm ESR} follows a T^{1.5}-behavior without the appearance of a coherence peak.

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N. Pascher, J. Deisenhofer, H. -A. Krug von Nidda, M. Hemmida, H. S. Jeevan, P. Gegenwart, A. Loidl. 2010-01-08. Magnetic fluctuations and superconductivity in Fe pnictides probed by electron spin resonance. https://doi.org/10.1103/physrevb.82.054525

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