Building blocks of an artificial kagome spin ice: Photoemission electron microscopy of arrays of ferromagnetic islands

E. Mengotti, L. J. Heyderman, A. Fraile Rodríguez, A. Bisig, L. Le Guyader, F. Nolting, and H. B. Braun
Phys. Rev. B 78, 144402 – Published 3 October 2008

Abstract

Arrays of dipolar coupled ferromagnetic islands arranged in specific geometries provide ideal systems to directly study frustration. We have examined with photoemission electron microscopy the magnetic configurations in three basic building blocks of an artificial kagome spin ice consisting of one, two, and three rings. The kagome spin ice arrangement is particularly interesting because it is highly frustrated and the three interactions at a vertex are equivalent. Employing dipolar energy calculations, we are able to make a full characterization of the magnetic states and therefore identify the lowest energy states. Experimentally we find that the ice rule is always obeyed even at low dipolar coupling strengths. However, as the number of rings increases there is a drastic decrease in the ability to achieve the low-energy states via demagnetization, a behavior also identified in the magnetization reversal. This carries the implication that the ground state will never be achieved in the infinite system. Finally, we show that at low coupling, the applied field direction governs the resulting states. This work opens the door to a novel class of systems for future spintronic applications.

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  • Received 26 June 2008

DOI:https://doi.org/10.1103/PhysRevB.78.144402

©2008 American Physical Society

Authors & Affiliations

E. Mengotti1, L. J. Heyderman1,*, A. Fraile Rodríguez1, A. Bisig1, L. Le Guyader1, F. Nolting1, and H. B. Braun2

  • 1Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
  • 2School of Physics, University College Dublin, Belfield, National University of Ireland, Dublin 4, Ireland

  • *laura.heyderman@psi.ch

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Vol. 78, Iss. 14 — 1 October 2008

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