We present magnetoresistance measurements on all-amorphous ferromagnet (F)/superconductor (S) heterostructures. The F/S/F trilayers show large magnetoresistance peaks in a small field range around the coercive field of the F layers, at temperatures within and below the superconducting transition. This is interpreted as flux flow of weakly pinned vortices induced by the stray field of Bloch magnetic domains in the F layers. Bilayers show much smaller effects, implying that the Bloch walls of the F layers in the trilayer line up and focus the stray fields. The data are used to discuss the expected minimum F-layer thickness needed to nucleate vortices.
|Number of pages||6|
|Journal||Physical Review B: Condensed Matter and Materials Physics|
|Publication status||Published - Dec 2006|