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MA: Magnetismus

MA 2: Magnetic Thin Films I

MA 2.5: Vortrag

Montag, 27. März 2006, 11:15–11:30, HSZ 03

Second-order magnetoelastic coupling of strained Fe — •Z. Tian, C.S. Tian, D. Sander, and J. Kirschner — Max-Planck-Institut für Mikrostrukturphysik,

Lattice strain is often the decisive factor which determines the magnetic anisotropy of ferromagnetic monolayers (ML). We performed combined cantilever bending beam and magneto-optical Kerr-effect measurements to determine the correlation between film stress, strain and the magnetic anisotropy of Fe ML deposited on Ir(001). The Fe ML are under compressive stress, as expected from the mismatch of 4.9% between bcc Fe and Ir. We use in-situ stress measurements to determine the lattice strain. The magnetoelastic coupling coefficient B₂ is determined from the change of crystal curvature upon switching the magnetization along the length and width of the sample. The value of B₂ deviates from the bulk value and depends on the film strain є. The experimental data suggest a linear dependence of B₂ on lattice strain as given by B₂^eff=B₂^bulk+D₂  є, with the bulk value B₂^bulk=7.83 MJ/m³, D₂=-350 MJ/m³. Our results extend the experimental data base[1] to compressive strain. This result indicates the decisive role of second-order magnetoelastic effects for the magnetic anisotropy of strained Fe ML, where reliable theoretical values have not been obtained yet[2].

[1] G.Wedler, J. Waly, A. Greuer and R. Koch: Phys. Rev. B 60, R11313 (1999).

[2] M. Fähnle, M. Komelj: Z. Metallkd. 93, 970 (2002).