Fe and Ni Bi and Tri-layers on Cu(100): Manipulating the Easy Magnetization Direction

J. Hunter-Dunn,1 D. Arvanitis,2 O. Karis,2 R. Carr3

1MAX-lab, Lund University
2Uppsala University

Ultra thin films of Ni deposited on the (100) surface of a Cu single crystal exhibit an in-plane magnetic anisotropy. At greater thicknesses the easy direction is out of plane. In contrast, ultra thin films of Fe deposited on the same surface exhibit a perpendicular magnetic anisotropy. The interesting question addressed in this talk is, what happens to the magnetisation direction when bi and tri-layers of ultra-thin Fe and Ni films are deposited on Cu(100)? We demonstrate how systematically varying the thickness of each element enabled us to stabilise systems with either in-plane or out-of-plane magnetic easy directions. We could therefore study cases where the easy direction does not correspond to that of the single layer on Cu(100). This could be done for both Fe/Ni/Cu(100), and Ni/Fe/Cu(100) as well as Ni/Fe/Ni/Cu(100) and Fe/Ni/Fe/Cu(100) structures.

From in situ x-ray magnetic circular dichroism measurements at BL 5.2 we were able to determine the spin and orbital moments per atom in these systems for each element and for each step of the preparation process. From these moments, and element specific hysteresis measurements, we present a qualitative picture of the magnetisation easy direction in terms of the competing anisotropy energies.

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