Domain-wall movement control in Co/Au multilayers by He(+)-ion-bombardment-induced lateral coercivity gradients.

Defined perpendicular anisotropy gradients in the Co sublayers of a [Co(0.6  nm)/Au(2  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.