title: Magnetic particles confined in a modulated channel: structural transitions tunable by tilting a magnetic field.
abstract: The ground state of colloidal magnetic particles in a modulated channel are investigated as a function of the tilt angle of an applied magnetic field. The particles are confined by a parabolic potential in the transversal direction while in the axial direction a periodic substrate potential is present. By using Monte Carlo simulations, we construct a phase diagram for the different crystal structures as a function of the magnetic field orientation, strength of the modulated potential, and the commensurability factor of the system. Interestingly, we found first- and second-order phase transitions between different crystal structures, which can be manipulated by the orientation of the external magnetic field. A reentrant behavior is found between two- and four-chain configurations, with continuous second-order transitions. Novel configurations are found consisting of frozen solitons of defects. By changing the orientation and/or strength of the magnetic field and/or the strength and periodicity of the substrate potential, the system transits through different phases.
authors.affiliation: Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium.
authors.forename: J E
authors.initials: JE
authors.lastname: Galván-Moya
authors.affiliation: Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium and Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceará, Brazil.
authors.forename: D
authors.initials: D
authors.lastname: Lucena
authors.affiliation: Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceará, Brazil.
authors.forename: W P
authors.initials: WP
authors.lastname: Ferreira
authors.affiliation: Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium and Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceará, Brazil.
authors.forename: F M
authors.initials: FM
authors.lastname: Peeters