Exchange coupling and magnetic anisotropy at Fe/FePt interfaces

C. J. Aas, P. J. Hasnip, R. Cuadrado, E. M. Plotnikova, L. Szunyogh, L. Udvardi, and R. W. Chantrell
Phys. Rev. B 88, 174409 – Published 13 November 2013

Abstract

We perform fully relativistic first-principles calculations of the exchange interactions and the magnetocrystalline anisotropy energy (MAE) in an Fe/FePt/Fe sandwich system in order to elucidate how the presence of Fe/FePt (soft/hard magnetic) interfaces impacts on the magnetic properties of Fe/FePt/Fe multilayers. Throughout our study we make comparisons between a geometrically unrelaxed system and a geometrically relaxed system. We observe that the Fe layer at the Fe/FePt interface plays a crucial role inasmuch as its (isotropic) exchange coupling to the soft (Fe) phase of the system is substantially reduced. Moreover, this interfacial Fe layer has a substantial impact on the MAE of the system. We show that the MAE of the FePt slab, including the contribution from the Fe/FePt interface, is dominated by anisotropic intersite exchange interactions. Our calculations indicate that the change in the MAE of the FePt slab with respect to the corresponding bulk value is negative, i.e., the presence of Fe/FePt interfaces appears to reduce the perpendicular MAE of the Fe/FePt/Fe system. However, for the relaxed system, this reduction is marginal. It is also shown that the relaxed system exhibits a reduced interfacial exchange. Using a simple linear chain model, we demonstrate that the reduced exchange leads to a discontinuity in the magnetization structure at the interface.

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  • Received 13 June 2013

DOI:https://doi.org/10.1103/PhysRevB.88.174409

©2013 American Physical Society

Authors & Affiliations

C. J. Aas1, P. J. Hasnip1, R. Cuadrado1, E. M. Plotnikova1, L. Szunyogh2,3, L. Udvardi2,3, and R. W. Chantrell1

  • 1Department of Physics, University of York, York YO10 5DD, United Kingdom
  • 2Department of Theoretical Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary
  • 3Condensed Matter Research Group of Hungarian Academy of Sciences, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary

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Vol. 88, Iss. 17 — 1 November 2013

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