Controlled magnetic behavior of [Co/Pt]n multilayer by tuning the topography of 2D nanobowl arrays

• Ordered [Co/Pt]n nanobowl arrays are fabricated based on PS bead template.
• The magnetic properties of [Co/Pt]n nanobowl arrays are tunable.
• The nanobowls smaller than 40 nm do not exhibit a complete reversing of vortex state.

Two topographies of [Co/Pt]n multilayer nanobowl arrays, connected nanobowls and separated nanobowls, are fabricated based on monolayer PS bead array substrate. The defects and dislocations induced by the notches between neighbor nanobowls in connected nanobowls arrays create larger stress, which leads to the coercivity enhancement. Compared to the connected nanobowl arrays, the separated nanobowl arrays show perfect morphology with smooth bowl caliber. And the sizes and distances between neighbor nanobowls can be tuned by etching PS beads so that the magnetic property of multilayer can be controlled. The separated nanobowl arrays with the small diameters exhibit perpendicular anisotropy although the vortex state occurs in the process of magnetization reversing, which are ascribed to strong dipolar interactions caused by neighbor nanobowls.