P. Isberg

Magnetic anisotropy and exchange coupling in FenVm(0 0 1) superlattices on MgO(0 0 1)

Abstract Fe(0 0 1) single layers and FenVm(0 0 1) superlattices were epitaxially grown on MgO(0 0 1) substrates, where n and m denote the number of monolayers (ML) of the constituents within each modulation period. n and m were varied between 3 and 14 ML. Structural characterization, performed by X-ray diffraction, revealed excellent reproduction in the repeat length A and good crystal quality. The samples were found, via Vibrating Sample Magnetometry and Ferromagnetic Resonance in combination with magneto-optic Kerr effect experiments, to exhibit an anisotropic in-plane behavior with the easy-axis being the [1 0 0] crystallographic direction, revealing the expected single crystalline properties. The anisotropy vanishes at small Fe-layer thickness which originate in a competition between a volume and surface anisotropy. Hysteresis loops with bilinear and biquadratic exchange coupling features were recorded for a V interlayer thickness of 13 ML and were theoretically reproduced using a phenomenological model.

In-plane magnetic anisotropy of Fe/V (0 0 1) superlattices

Abstract The magnetization and the in-plane magnetic anisotropy energy of Fe (15 ML )/ V (1 – 12 ML ) superlattices have been examined and their relation to the growth of the superlattices is discussed. The individual lattice parameters of the strained Fe and V layers are calculated theoretically from the elastic energy. The calculations rather accurately reproduce the experimentally derived average lattice parameters of the superlattices. The measured in-plane magnetic anisotropy is compared to calculated results employing bulk values of the anisotropy constants and magnetoelastic coupling coefficients. A good agreement between the results is found provided interface coefficients are included in the calculations. A first principles study reproduces an observed reduction in saturation moments of the interface and is shown to be caused by an induced moment on the interface V atoms that couple antiparallel to the Fe moments in combination with a reduction of the magnetic moments of the Fe atoms at the interface. A theoretical calculation of bulk Fe reproduces the experimental ‘bulk’ contribution to the magnetocrystalline anisotropy and the magnetoelastic coupling of the films.

Probe depth variation in grazing exit soft-X-ray emission spectroscopy

Abstract The angular dependence of soft X-ray emission spectra from a sandwich structured sample has been studied. Greatly enhanced surface sensitivity is observed at grazing emission. Soft X-ray emission allows chemical state information to be obtained owing to high spectral resolution and small lifetime broadening. Well-established theory from grazing incidence X-ray fluorescence spectroscopy has been used to evaluate and interpret the experimental data.