Magnetoelastic and total anisotropy effects on the domain-wall dynamics in the polycrystalline state

• Published in: Journal of magnetism and magnetic materials Vol. 159; no. 3; pp. 331 - 336
• Main Authors: Nedkov, I., Gyuot, M., Cagan, V.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.1996
• Subjects: Anisotropy; Domain-wall dynamics; Ferrites; Magnetostriction; Stress anisotropy; Ferrites; Stress anisotropy; Domain-wall dynamics; Magnetostriction; Anisotropy
• ISSN: 0304-8853
• DOI: 10.1016/0304-8853(95)00944-2

This work investigates the domain-wall (DW) mobility due to magnetoelastic interaction. Polycrystalline samples with high grain-size homogeneity were prepared based on the general formula Y 3Fe 5- x Mn x O 12 (0 < x < 0.28). A series of samples was especially selected where the longitudinal magnetostriction changed from −2.14 × 10 −6 to +7.65 × 10 −6 at 300 K, while the single-crystal crystalline anisotropy constant K 1 remained negative. The effects of the magnetostriction and the total anisotropy K on the complex magnetic permeability spectrum μ ∗(f) were investigated in a broad frequency range (0.3–3 GHz). Two characteristic regions of variation of the real (μ′) and the imaginary (μ″) parts of the complex permeability as functions of λ s were established. Near λ s = 0, a resonance-type spectrum was observed. The model of ‘diametrical spherical DW’ is inapplicable for λ s ⪢ 0 - the DW dynamics is then influenced exclusively by the stress anisotropy and by the strong isotropic exchange stress arising from the anisotropic magnetostrictive deformation constrained by the neighboring grains. The significant decrease of the initial permeability in this region can be explained by the rise in the concentration of DW not having a 180° orientation.