| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1817504 | Physica C: Superconductivity and its Applications | 2015 | 4 Pages |
•We have fabricated superconducting shifted strip arrays (SSAs) up to 4 layers.•Flux penetrations into SSAs are observed by using magneto-optical imaging.•Linear flux avalanches are observed in a wider range of overlap in the 4-layer SSAs than in the 2- or 3-layer SSAs.
We have fabricated multi-layer superconducting shifted strip arrays (SSAs) of Nb up to 4 layers and systematically studied the vortex penetrations into these structures. We observed the vortex penetration as a function of the number of layers and the ratio of overlap between neighboring layers by using magneto-optical (MO) imaging. In the case of 2- and 3-layer SSAs, spot-like avalanches occur when the overlap is small, while linear avalanches occur when the overlap is large, consistent with our previous reports. In the 4-layer SSAs, the smallest limit of the overlap between the neighboring layers for the linear avalanche is lower. Flux penetrations parallel to the strip which were observed in the 3-layer SSA were also observed in the 4-layer SSAs with smaller ratio of overlap. Larger demagnetization effects in the middle two layers in 4-layer SSA help to make avalanches larger and more extended.
