P. Moch

Co2FeAl thin films grown on MgO substrates: Correlation between static, dynamic, and structural properties

Co2FeAl (CFA) thin films with thickness varying from 10 nm to 115 nm have been deposited on MgO(001) substrates by magnetron sputtering and then capped by Ta or Cr layer. X-rays diffraction (XRD) revealed that the cubic

Co2FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

[001]

Brillouin light scattering by magnetic surface waves in dot-structured permalloy layers

CFA axis is normal to the substrate and that all the CFA films exhibit full epitaxial growth. The chemical order varies from the

Spin waves in magnetic wires:: a Brillouin study

B2

Spin waves in a magnetic stripe submitted to a perpendicular magnetic field

phase to the

Spin waves calculations in magnetic stripes

A2

BRILLOUIN INVESTIGATION OF THE DYNAMIC PROPERTIES OF COBALT WIRE ARRAYS

phase when decreasing the thickness. Magneto-optical Kerr effect (MOKE) and vibrating sample magnetometer measurements show that, depending on the field orientation, one or two-step switchings occur. Moreover, the films present a quadratic MOKE signal increasing with the CFA thickness, due to the increasing chemical order. Ferromagnetic resonance, MOKE transverse bias initial inverse susceptibility and torque (TBIIST) measurements reveal that the in-plane anisotropy results from the superposition of a uniaxial and of a fourfold symmetry term. The fourfold anisotropy is in accord with the crystal structure of the samples and is correlated to the biaxial strain and to the chemical order present in the films. In addition, a large negative perpendicular uniaxial anisotropy is observed. Frequency and angular dependences of the FMR linewidth show two magnon scattering and mosaicity contributions, which depend on the CFA thickness. A Gilbert damping coefficient as low as 0.0011 is found.

Static and dynamic magnetic properties of epitaxial Fe1.7Ge thin films grown on Ge(111)

10 nm and 50 nm Co2FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to CFA(001)[110]//MgO(001)[100] epitaxial relation) for CFA films grown on a Si and on a MgO substrate, respectively. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (Ta), while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing Ta, while the uniaxial anisotropy field is nearly unaffected by Ta within the ...

Raman scattering and soft mode in TlTiOPO4

Abstract Brillouin light scattering was used to investigate the magnetic properties of periodic arrays of square dots of permalloy obtained by electron beam lithography and ion beam sputtering from evaporated films. The frequencies of the magnetostatic surface waves were studied for square 2 μm × 2 μm dots of thickness 30 nm separated by intervals of 1 μm, and the results were compared to those obtained from the unpatterned permalloy film. The spin wave frequencies were found to be sensitive to the size of the dots and to the direction of the applied field; at first view, the size dependence is reasonably interpreted to derive from the demagnetizing field effect. However, a closer inspection of the dependence of the frequencies versus the angle of incidence seems to show step-like variations, suggesting that the involved in-plane wave-vector could be locked and show quantized values related to the finite dimensions of the dots. Consequently, the simple model, based on the Damon-Eshbach expression modified by the demagnetizing field, appears to be insufficient, and the full description of the magnetic surface wave properties has to take into account their lateral confinement.

Shape effect on in-plane anisotropy in magnetic dots

Abstract A detailed Brillouin light scattering study of the dispersion of surface spin waves in cobalt wires is reported. A comparison with the dispersion curve of the unpatterned continuos film is achieved and the effects of the size-dependent demagnetizing field are discussed. Concerning the pseudo-bulk modes appearing in the patterned film, as expected, their variation is quasi-independent from the variation of the angle of incidence. The experimental Brillouin spectra do not display any splitting of the Damon–Eshbach mode into a set of discrete lines in contrast with previously published results on permalloy. We interpret this difference as arising from the large experimental linewidth combined with the presence of an anisotropy in the case of cobalt. A qualitative model of the scattering intensity is presented in order to illustrate this difference. The involved eigenfrequencies are derived from numerical calculations which also allow us to discuss the relevant quantization conditions of the in-plane wave vector.