title: Dynamic trajectory analysis of superparamagnetic beads driven by on-chip micromagnets.
abstract: We investigate the non-linear dynamics of superparamagnetic beads moving around the periphery of patterned magnetic disks in the presence of an in-plane rotating magnetic field. Three different dynamical regimes are observed in experiments, including (1) phase-locked motion at low driving frequencies, (2) phase-slipping motion above the first critical frequency fc1, and (3) phase-insulated motion above the second critical frequency fc2. Experiments with Janus particles were used to confirm that the beads move by sliding rather than rolling. The rest of the experiments were conducted on spherical, isotropic magnetic beads, in which automated particle position tracking algorithms were used to analyze the bead dynamics. Experimental results in the phase-locked and phase-slipping regimes correlate well with numerical simulations. Additional assumptions are required to predict the onset of the phase-insulated regime, in which the beads are trapped in closed orbits; however, the origin of the phase-insulated state appears to result from local magnetization defects. These results indicate that these three dynamical states are universal properties of bead motion in non-uniform oscillators.
authors.affiliation: Department of Emerging Materials Science, DGIST , Daegu 711-873, South Korea.
authors.forename: Xinghao
authors.initials: X
authors.lastname: Hu
authors.affiliation: Department of Mechanical Engineering and Materials Science, Duke University , Box 90300 Hudson Hall, Durham, North Carolina 27708, USA.
authors.forename: Roozbeh
authors.initials: R
authors.lastname: Abedini-Nassab
authors.affiliation: Department of Emerging Materials Science, DGIST , Daegu 711-873, South Korea.
authors.forename: Byeonghwa
authors.initials: B
authors.lastname: Lim
authors.affiliation: Department of Mechanical Engineering and Materials Science, Duke University , Box 90300 Hudson Hall, Durham, North Carolina 27708, USA.
authors.forename: Ye
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Physics, The Ohio State University , 191 W. Woodruff Avenue, Columbus, Ohio 43220, USA.
authors.forename: Marci
authors.initials: M
authors.lastname: Howdyshell
authors.affiliation: Department of Physics, The Ohio State University , 191 W. Woodruff Avenue, Columbus, Ohio 43220, USA.
authors.forename: Ratnasingham
authors.initials: R
authors.lastname: Sooryakumar
authors.affiliation: Department of Mechanical Engineering and Materials Science, Duke University , Box 90300 Hudson Hall, Durham, North Carolina 27708, USA.
authors.forename: Benjamin B
authors.initials: BB
authors.lastname: Yellen
authors.affiliation: Department of Emerging Materials Science, DGIST , Daegu 711-873, South Korea.
authors.forename: CheolGi
authors.initials: C
authors.lastname: Kim