CNR ExploRA

Articolo in rivista, 2009, ENG, 10.1007/s10948-009-0477-6

Granularity and Linear Flux Dynamics in Sintered LaO0.92F0.08FeAs

Zola, D. and Polichetti, M. and Adesso, M. G. and Fittipaldi, R. and Cirillo, C. and Luo, J. and Chen, G. F. and Li, Z. and Wang, N. L. and Vecchione, A. and Attanasio, C. and Noce, C. and Pace, S.

Zola, D (Reprint Author), INFM, CNR, Lab Regionale SuperMat, Baronissi, SA, Italy. Zola, D.; Polichetti, M.; Adesso, M. G.; Fittipaldi, R.; Cirillo, C.; Vecchione, A.; Attanasio, C.; Noce, C.; Pace, S., INFM, CNR, Lab Regionale SuperMat, Baronissi, SA, Italy. Zola, D.; Polichetti, M.; Adesso, M. G.; Fittipaldi, R.; Cirillo, C.; Vecchione, A.; Attanasio, C.; Noce, C.; Pace, S., Univ Salerno, Dipartimento Fis ER Caianiello, I-84081 Baronissi, SA, Italy. Luo, J.; Chen, G. F.; Li, Z.; Wang, N. L., Chinese Acad Sci, Inst Phys, Beijing Natl Lab Condensed Matter Phys, Beijing 100190, Peoples R China.

The flux dynamics in LaO0.92F0.08FeAs polycrystalline samples has been investigated looking at the first and higher harmonics of the AC magnetic susceptibility. The investigation of the real and imaginary part of the first harmonic shows that the critical temperature is reduced when the applied DC field increases. Moreover, the intergrain and intragrain contributions persist up to the highest applied DC field, suggesting that the electromagnetic connection among the superconducting grains is strong in spite of the estimated very short coherence length. Concerning the higher harmonics, a comparison between the absolute value of the real part of the first harmonic and the sum of the higher harmonics clearly indicates the activation of a linear regime below the superconducting critical temperature. Furthermore, the temperature range where this linear regime is activated is smaller than the one found in cuprate perovskite superconductors.

Journal of superconductivity and novel magnetism 22 (6), pp. 609–612