Abstract
We investigate the ac susceptibility of both field-cooled and zero-field-cooled sintered granular thin slabs and powders in low magnetic fields. The ac susceptibility of the granular thin slabs appears to depend upon the magnetic history for dc fields larger than a certain value, , with the existence of the stronger diamagnetic signal (the in-phase part of the ac susceptibility) in the field-cooled case. Our results show that the difference in local flux distributions between the field-cooled case and the zero-field-cooled case exists even for a dc field as low as several Oe, a value much lower than the bulk lower critical field (). The upper limit of a homogeneous superconducting area determined from appears comparable to the average grain size in our granular thin slabs. The existence of is attributed to the superconducting glass behavior of granular with disorder in the intergranular Josephson junctions.
- Received 9 February 1995
DOI:https://doi.org/10.1103/PhysRevB.51.16302
©1995 American Physical Society