title: Topological repulsion between domain walls in magnetic nanowires leading to the formation of bound states.
abstract: Head-to-head and tail-to-tail magnetic domain walls in nanowires behave as free magnetic monopoles carrying a single magnetic charge. Since adjacent walls always carry opposite charges, they attract one another. In most cases this long-range attractive interaction leads to annihilation of the two domain walls. Here, we show that, in some cases, a short-range repulsive interaction suppresses annihilation of the walls, even though the lowest energy state is without any domain walls. This repulsive interaction is a consequence of topological edge defects that have the same winding number. We show that the competition between the attractive and repulsive interactions leads to the formation of metastable bound states made up of two or more domain walls. We have created bound states formed from up to eight domain walls, corresponding to the magnetization winding up over four complete 360° rotations.
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA. lucthom@us.ibm.com
authors.forename: Luc
authors.initials: L
authors.lastname: Thomas
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Hayashi
authors.forename: Rai
authors.initials: R
authors.lastname: Moriya
authors.forename: Charles
authors.initials: C
authors.lastname: Rettner
authors.forename: Stuart
authors.initials: S
authors.lastname: Parkin