title: Bistability of vortex core dynamics in a single perpendicularly magnetized nanodisk.
abstract: Microwave spectroscopy of individual vortex-state magnetic nanodisks in a perpendicular bias magnetic field H is performed using a magnetic resonance force microscope. It reveals the splitting induced by H on the gyrotropic frequency of the vortex core rotation related to the existence of the two stable polarities of the core. This splitting enables spectroscopic detection of the core polarity. The bistability extends up to a large negative (antiparallel to the core) value of the bias magnetic field Hr, at which the core polarity is reversed. The difference between the frequencies of the two stable rotational modes corresponding to each core polarity is proportional to H and to the ratio of the disk thickness to its radius. Simple analytic theory in combination with micromagnetic simulations give a quantitative description of the observed bistable dynamics.
authors.affiliation: Service de Physique de l'Etat Condensé (CNRS URA 2464), CEA Saclay, 91191 Gif-sur-Yvette, France. gregoire.deloubens@cea.fr
authors.forename: G
authors.initials: G
authors.lastname: de Loubens
authors.forename: A
authors.initials: A
authors.lastname: Riegler
authors.forename: B
authors.initials: B
authors.lastname: Pigeau
authors.forename: F
authors.initials: F
authors.lastname: Lochner
authors.forename: F
authors.initials: F
authors.lastname: Boust
authors.forename: K Y
authors.initials: KY
authors.lastname: Guslienko
authors.forename: H
authors.initials: H
authors.lastname: Hurdequint
authors.forename: L W
authors.initials: LW
authors.lastname: Molenkamp
authors.forename: G
authors.initials: G
authors.lastname: Schmidt
authors.forename: A N
authors.initials: AN
authors.lastname: Slavin
authors.forename: V S
authors.initials: VS
authors.lastname: Tiberkevich
authors.forename: N
authors.initials: N
authors.lastname: Vukadinovic
authors.forename: O
authors.initials: O
authors.lastname: Klein