Abstract
The AC susceptibility, chi, at zero DC magnetic field of a polycrystalline sample of LaFeAsO_{0.94}F_{0.06} (Tc ≈ 24 K) has been investigated as a function of the temperature, the amplitude of the AC magnetic field (in the range Hac = 0.003 Oe - 4 Oe) and the frequency (in the range f = 10 kHz - 100 kHz). The chi(T) curve exhibits the typical two-step transition arising from the combined response of superconducting grains and intergranular weak-coupled medium. The intergranular part of chi strongly depends on both the amplitude and the frequency of the AC driving field, from few Kelvin below Tc down to T = 4.2 K. Our results show that, in the investigated sample, the intergrain critical current is not determined by pinning of Josephson vortices but by Josephson critical current across neighboring grains.
Lingua originale | English |
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pagine (da-a) | 40-51 |
Numero di pagine | 12 |
Rivista | Journal of Low Temperature Physics |
Volume | 162 |
Stato di pubblicazione | Published - 2011 |
All Science Journal Classification (ASJC) codes
- ???subjectarea.asjc.3100.3107???
- ???subjectarea.asjc.2500.2500???
- ???subjectarea.asjc.3100.3104???