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Séminaire MCMF

Jeudi 8 novembre à 14h30 Salle Erwin Bertaut, F418 "Magnetic properties of ultrathin Fe films on Ag(116) investigated by resonant soft x-ray reflectivity"

Oratrice : Emmanuelle Jal (Institut Néel, MCMF, équipe Surfaces, Interfaces et Nanostructures )

Magnetic anisotropy is one of the key properties for the applications in magnetoelectronics. Near interfaces this anisotropy can be modified by symmetry breaking. The anisotropy of Fe films grown on a stepped substrate Ag(116) depends on the film thickness, the step density, the covering material and the temperature [1,2]. Magneto-Optic Kerr Effect (MOKE) experiments on Au/Fe/Ag(116) have shown that, at room temperature, the easy magnetization axis (EMA) rotates from parallel to perpendicular to the steps when the Fe thickness is reduced. At low temperature (LT), an oscillation of the anisotropy strength is observed [1] and leads to an oscillation of the EMA. Furthermore, it has been shown by polar MOKE that for an EMA perpendicular to the steps, an out of plane magnetic component exists and oscillates with the same periodicity than the EMA one. However, MOKE measurements probe only the average characteristics of the magnetization throughout the magnetic films. In order to get more insights in the understanding of the magnetic properties changes, especially in the case of different interfaces, the depth-resolved magnetization profile has been addressed using soft x-ray resonant magnetic reflectivity [3]. First, I will describe the technique : its principle, its application and its analysis. Then, I will present the results obtained for a Fe layer grown on a stepped Ag(116) and covered by Au. I will show how the approach is sensitive to the three components of magnetization, to the enhancement of the magnetic moment at both interfaces, to the distribution of the out plane component.

[1] J. Li et al., Phys. Rev. Lett. 102, 207206 (2009)
[2] U. Bauer et al., Phys. Rev. B 81, 134428 (2010)
[3] J.-M. Tonnerre et al., Phys. Rev. B 84, 100407(R) (2011)

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