Berlin 2015 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 46: Magnetic Thin Films I

MA 46.9: Vortrag

Donnerstag, 19. März 2015, 17:15–17:30, H 1012

Layer-resolved in-situ ⁵⁷Fe conversion electron Mössbauer spectroscopy (CEMS) on 4 ML Fe(001)/Ir(001) at 30 K — •Sergey Makarov^1,2, Werner Keune^1,2, Heiko Wende¹, and Jürgen Kirschner² — ¹Faculty of Physics and CeNIDE, University of Duisburg-Essen — ²Max Planck Institute of Microstructure Physics

Our recent in-situ ⁵⁷Fe Mössbauer spectroscopy (CEMS) measurements in UHV on the Fe(001)/Ir(001) system have provided experimental prove of magnetic order in Fe(001)/Ir(001) ultrathin films below four atomic Fe monolayers (< 4 ML) at 30 K, and the average spin canting angle <Θ> (rel. to the surface normal direction) was extracted. The result is consistent with a ground state helical spin configuration in 2 ML and 3 ML Fe(001)/Ir(001) [1]. Moreover, the existence of two inequivalent Fe sites in terms of fct and bct Fe was discussed [2].
In the present work we focus on in-situ ⁵⁷Fe CEMS measurements of layer-dependent magnetic ordering in homogeneous 4 ML Fe(001)/Ir(001) films resolved by a 2 ML ⁵⁷Fe probe layer placed at different positions with respect to Ir(001). We conclude that site 1 of fct Fe has a higher abundance near the Fe/Ir interface than in the rest of the film (the opposite is valid for site 2 of bct Fe). We observe a weak tendency for a layer-dependence of the angle <Θ>. The sum spectrum of all tracer layers agrees well with the spectrum of a homogeneous 4 ML ⁵⁷Fe(001)/Ir(001) film.

[1] A. Deák et al., Phys. Rev. B 84 (2011) 224413

[2] V. Martin et al., Phys. Rev. B 76 (2007) 205418