Journal of Nanoparticle Research

, Volume 13, Issue 11, pp 6075–6083

The effect of the single-spin defect on the stability of the in-plane vortex state in 2D magnetic nanodots

  • S. Mamica
  • J.-C. S. Lévy
  • Ph. Depondt
  • M. Krawczyk
Special Issue: Nanostructured Materials 2010

Abstract

The aim of this study is to analyse the stability of the single in-plane vortex state in two-dimensional magnetic nanodots with a nonmagnetic impurity (single-spin defect) at the centre. Small square and circular dots including up to a few thousand of spins are studied by means of a microscopic theory with nearest-neighbour exchange interactions and dipolar interactions fully taken into account. We calculate the spin-wave frequencies versus the dipolar-to-exchange interaction ratio d to find the values of d for which the assumed state is stable. Transitions to other states and their dependence on d and the vortex size are investigated as well, with two types of transition found: vortex core formation for small d values (strong exchange interactions), and in-plane reorientation of spins for large d values (strong dipolar interactions). Various types of localized spin waves responsible for these transitions are identified.

Keywords

Magnetic nanodots Magnetic vortices Localized spin waves Ground state stability 

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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • S. Mamica
    • 1
  • J.-C. S. Lévy
    • 2
  • Ph. Depondt
    • 3
  • M. Krawczyk
    • 1
  1. 1.Surface Physics Division, Faculty of PhysicsA. Mickiewicz UniversityPoznańPoland
  2. 2.Lab. MPQ, UMR CNRS 7162Université Paris 7ParisFrance
  3. 3.INSP, UMR CNRS 7588Université Paris 6Paris Cedex 05France

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