Domain-Wall Movement Control inCo/AuMultilayers byHe+-Ion-Bombardment-Induced Lateral Coercivity Gradients

Defined perpendicular anisotropy gradients in the Co sublayers of a $[\mathrm{Co}(0.6\text{ }\text{ }\mathrm{nm})/\mathrm{Au}(2\text{ }\text{ }\mathrm{nm}){]}_{3}$ sputter-deposited multilayer have been introduced by light ion bombardment through a wedged Au stopper layer. Within such a layer system, domain walls between up- and down-magnetized areas are controllably movable by an external perpendicular homogeneous magnetic field. This method and layer system is very promising for a controlled magnetic particle transport within the stray fields of the moving domain walls.