We use local and global magnetometry measurements to study the influence of magnetic domain width w on the domain-induced vortex pinning in superconducting/ferromagnetic bilayers, built of a Nb film and a ferromagnetic Co/Pt multilayer with perpendicular magnetic anisotropy, with an insulating layer to eliminate proximity effect. The quasi-periodic domain patterns with different and systematically adjustable width w, as acquired by a special demagnetization procedure, exert tunable vortex pinning on a superconducting layer. The largest enhancement of vortex pinning, by a factor of more than 10, occurs when w ~ 310 nm is close to the magnetic penetration depth.
@article{arxiv.1107.3743,
title = {Enhancement of vortex pinning in superconductor/ferromagnet bilayers via angled demagnetization},
author = {Marta Z. Cieplak and L. Y. Zhu and Z. Adamus and M. Konczykowski and C. L. Chien},
journal= {arXiv preprint arXiv:1107.3743},
year = {2015}
}