title: Trapping of topological-structural defects in Coulomb crystals.
abstract: We study experimentally and theoretically structural defects which are formed during the transition from a laser cooled cloud to a Coulomb crystal, consisting of tens of ions in a linear radio frequency trap. We demonstrate the creation of predicted topological defects ("kinks") in purely two-dimensional crystals and also find kinks which show novel dynamical features in a regime of parameters not considered before. The kinks are always observed at the center of the trap, showing a large nonlinear localized excitation, and the probability of their occurrence saturates at ∼0.5. Simulations reveal a strong anharmonicity of the kink's internal mode of vibration, due to the kink's extension into three dimensions. As a consequence, the periodic Peierls-Nabarro potential experienced by a discrete kink becomes a globally confining potential, capable of trapping one cooled defect at the center of the crystal.
authors.affiliation: Albert-Ludwigs-Universität Freiburg, Physikalisches Institut, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Mielenz
authors.forename: J
authors.initials: J
authors.lastname: Brox
authors.forename: S
authors.initials: S
authors.lastname: Kahra
authors.forename: G
authors.initials: G
authors.lastname: Leschhorn
authors.forename: M
authors.initials: M
authors.lastname: Albert
authors.forename: T
authors.initials: T
authors.lastname: Schaetz
authors.forename: H
authors.initials: H
authors.lastname: Landa
authors.forename: B
authors.initials: B
authors.lastname: Reznik