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Paper

Published as Rapid Communication in Physical Review B

A. Ghosh, K.S. Huang, and O. Tchernyshyov, “Annihilation of domain walls in a ferromagnetic wire,” Phys. Rev. B 95, 180408(R). [doi] [arXiv]

We study the annihilation of topological solitons in the simplest setting: a one-dimensional ferromagnet with an easy axis. We develop an effective theory of the annihilation process in terms of four collective coordinates: two zero modes of the translational and rotational symmetries Z and Φ, representing the average position and azimuthal angle of the two solitons, and two conserved momenta ζ and φ, representing the relative distance and twist. Comparison with micromagnetic simulations shows that our approach captures well the essential physics of the process.

Comments:	7 pages, 2 figures
Subjects:	Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Cite as:	arXiv:1702.02248 [cond-mat.mes-hall]

1702-02248

Presentations

Ghosh, A., Huang, K., Tchernyshyov, O. (2017, March). Annihilation of Domain Walls in a Ferromagnetic Wire. Oral session presented at the March Meeting of the American Physical Society, New Orleans, LA.

Abstract: B50.00003 : Annihilation of Domain Walls in a Ferromagnetic Wire

mws_mar17-2016-003943

11:39 AM–11:51 AM

Authors:

  Anirban Ghosh
(Department of Physics and Astronomy, Johns Hopkins University)

  Kevin Huang
(Department of Physics and Astronomy, Johns Hopkins University)

  Oleg Tchernyshyov
(Department of Physics and Astronomy, Johns Hopkins University)

We study the annihilation of topological solitons in one of the simplest systems that support them: a one-dimensional ferromagnetic wire with an easy axis along its length. In the presence of energy dissipation due to viscous losses, two solitons (domain walls) on the wire, when released from afar, approach each other and eventually annihilate to create a uniformly magnetized state. Starting from a class of exact solutions for stationary two-domain-wall configurations in the absence of dissipation [1], we develop an effective theory that describes this annihilation in terms of four collective coordinates: a) the two zero modes corresponding to the location of the center and the average azimuthal angle of the full structure and b) their two conjugate momenta which describe the relative twist and the relative separation of the two domain walls respectively [2]. Comparison with micromagnetic simulation on OOOMF confirms that this theory captures well the essential physics of the process. We believe this work will be a good starting point for studying the annihilation of more complicated topological solitons like vortices and skyrmions in ferromagnetic thin films. [1]A.M. Kosevich, B.A. Ivanov, A.S. Kovalev, Phys. Rep. 194, 117 (1990). [2]O. Tchernyshyov, Ann. Phys. 363, 98 (2015)

annihilation-of-domain-walls-in-a-ferromagnetic-wire-aps20171

Ghosh, A., Huang, K., Tchernyshyov, O. (2016, July). Annihilation of Ferromagnetic Domain Walls in One Dimension. Poster presented at the Seminar and Workshop Topological Patterns and Dynamics in Magnetic Elements and in Condensed Matter at the Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.