AC susceptibility of Sr2RuO4–Sr3Ru2O7 eutectics: Dependence on AC field strength and frequency

The low-field AC susceptibility of a eutectic crystal of the Sr2RuO4-Sr3Ru2O7 system exhibits superconducting transition features at three temperatures. We investigate the dependence on AC field strength from 0.021 to 2.1 Oe-rms and frequency from 17 to 3 kHz. The two lower-temperature peaks in the imaginary part originate in the Sr3Ru2O7 part. The lowest-temperature peak is exceedingly sensitive to the. eld amplitude and shifts to lower temperatures with increasing amplitude. By contrast, it slightly shifts to higher temperatures with increasing frequency. These results support that the sensitive features involve weak links forming the screening paths. (c) 2006 Published by Elsevier B.V.