1 research outputs found
Reentrant AC magnetic susceptibility in Josephson-junction arrays: An alternative explanation for the paramagnetic Meissner effect
The paramagnetic Meissner effect (PME) measured in high granular
superconductors has been attributed to the presence of -junctions between
the grains. Here we present measurements of complex AC magnetic susceptibility
from two-dimensional arrays of conventional (non ) Nb/Al/AlOx/Nb Josephson
junctions. We measured the susceptibility as a function of the temperature ,
the AC amplitude of the excitation field, , and the external magnetic
field, . The experiments show a strong paramagnetic contribution from
the multi-junction loops, which manifests itself as a reentrant screening at
low temperature, for values of higher than 50 mOe. A highly simplified
model, based on a single loop containing four junction, accounts for this
paramagnetic contribution and the range of parameters in which it appears. This
model offers an alternative explanation of PME which does not involve
-junctions.Comment: PDF file, 6 two-columns pages, 9 figure