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Steering Magnetic Skyrmions with Currents : A Nonequilibrium Green's Functions Approach

Viñas Boström, Emil LU and Verdozzi, Claudio LU (2019) In Physica Status Solidi (B) Basic Research
Abstract

Magnetic skyrmions, topologically protected vortex-like configurations in spin textures, are of wide conceptual and practical appeal, notably in relation to the making of so-called race-track memory devices. Skyrmions can be created, steered, and destroyed with magnetic fields and/or (spin) currents. Here the authors focus on the latter mechanism, analyzed via a microscopic treatment of the skyrmion–current interaction. The system considered is an isolated skyrmion in a square-lattice cluster, interacting with electron spins in a current-carrying quantum wire. For the theoretical description, a quantum formulation of spin-dependent currents via nonequilibrium Green's functions (NEGF) within the generalized Kadanoff–Baym ansatz (GKBA) is... (More)

Magnetic skyrmions, topologically protected vortex-like configurations in spin textures, are of wide conceptual and practical appeal, notably in relation to the making of so-called race-track memory devices. Skyrmions can be created, steered, and destroyed with magnetic fields and/or (spin) currents. Here the authors focus on the latter mechanism, analyzed via a microscopic treatment of the skyrmion–current interaction. The system considered is an isolated skyrmion in a square-lattice cluster, interacting with electron spins in a current-carrying quantum wire. For the theoretical description, a quantum formulation of spin-dependent currents via nonequilibrium Green's functions (NEGF) within the generalized Kadanoff–Baym ansatz (GKBA) is employed. This is combined with a treatment of skyrmions based on classical localized spins, with the skyrmion motion described via Ehrenfest dynamics. With the mixed quantum–classical scheme, the authors assess how time-dependent currents can affect the skyrmion dynamics, and how this in turn depends on electron–electron and spin–orbit interactions in the wire. This study shows the usefulness of a quantum–classical treatment of skyrmion steering via currents, as a way for example to validate/extract an effective, classical-only, description of skyrmion dynamics from a microscopic quantum modeling of the skyrmion–current interaction.

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publication status
published
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keywords
electron–spin interactions, generalized Kadanoff–Baym ansatz, nonequilibrium Green's functions, quantum–classical scheme, skyrmions
in
Physica Status Solidi (B) Basic Research
article number
1800590
publisher
John Wiley and Sons Inc.
external identifiers
  • scopus:85065212905
ISSN
0370-1972
DOI
10.1002/pssb.201800590
language
English
LU publication?
yes
id
38b101ee-47bc-4a5e-bfe8-278e5570798a
date added to LUP
2019-05-16 10:44:25
date last changed
2020-10-07 06:28:40
@article{38b101ee-47bc-4a5e-bfe8-278e5570798a,
  abstract     = {<p>Magnetic skyrmions, topologically protected vortex-like configurations in spin textures, are of wide conceptual and practical appeal, notably in relation to the making of so-called race-track memory devices. Skyrmions can be created, steered, and destroyed with magnetic fields and/or (spin) currents. Here the authors focus on the latter mechanism, analyzed via a microscopic treatment of the skyrmion–current interaction. The system considered is an isolated skyrmion in a square-lattice cluster, interacting with electron spins in a current-carrying quantum wire. For the theoretical description, a quantum formulation of spin-dependent currents via nonequilibrium Green's functions (NEGF) within the generalized Kadanoff–Baym ansatz (GKBA) is employed. This is combined with a treatment of skyrmions based on classical localized spins, with the skyrmion motion described via Ehrenfest dynamics. With the mixed quantum–classical scheme, the authors assess how time-dependent currents can affect the skyrmion dynamics, and how this in turn depends on electron–electron and spin–orbit interactions in the wire. This study shows the usefulness of a quantum–classical treatment of skyrmion steering via currents, as a way for example to validate/extract an effective, classical-only, description of skyrmion dynamics from a microscopic quantum modeling of the skyrmion–current interaction.</p>},
  author       = {Viñas Boström, Emil and Verdozzi, Claudio},
  issn         = {0370-1972},
  language     = {eng},
  month        = {01},
  publisher    = {John Wiley and Sons Inc.},
  series       = {Physica Status Solidi (B) Basic Research},
  title        = {Steering Magnetic Skyrmions with Currents : A Nonequilibrium Green's Functions Approach},
  url          = {http://dx.doi.org/10.1002/pssb.201800590},
  doi          = {10.1002/pssb.201800590},
  year         = {2019},
}