The vortex range in the Fe layer on the easy axis direction of Co layer. The Co layer easy axis deviates from the applied field direction by the angle of 0°, 30°, 60°, 90°. The asymmetric dots are characterized by α = 0, 0.25, 0.5, 0.75, 1. The solid and dash lines describe the vortex range calculated from the descending and ascending branches of the Fe layer loop, respectively.
Yan et al. Nanoscale Research Letters 2014 9:106 doi:10.1186/1556-276X-9-106