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Magnetic properties of highly magnetostrictive amorphous glass-coated microwires are strongly correlated to the presence of a glass coating that introduces a spatially inhomogeneous stress field distribution. We investigate the influence of mechanical stresses on the inclination of magnetic domain walls in magnetic microwires. Magneto-optical Kerr effect imaging is used to compare the tilted orientation of the domain wall shape in as-cast and annealed microwires. Angular dependencies of magnetization loops measured by alternating gradient field magnetometry reveal that the change of domain wall tilting with annealing is related to the decrease of magnetic anisotropy with axial orientation. Finally, micromagnetic simulations are used to show that sufficiently high uniaxial magnetic anisotropy gives rise to the presence of observed charged domain walls with tilted orientation. [ABSTRACT FROM AUTHOR]

Amorphous glass-coated Fe-Si-B-P microwires with an induced gradient of perpendicular magnetic anisotropy are studied. The angular dependence of the domain wall mobility in the perpendicular magnetic field is present in as-cast sample. After thermal annealing below the crystallization temperature, the effect of the perpendicular magnetic field is suppressed due to the relaxation of internal mechanical stresses. Moreover, the domain wall mobility decreases, and the critical field increases. The results are explained in terms of the release of mechanical stresses induced during production after annealing. Furthermore, a new mechanical stress distribution is induced due to the slow cooling rate after thermal annealing. Scanning electron microscopy images of annealed samples below and above the crystallization temperature suggest the presence of the gradient of perpendicular magnetic anisotropy. Directional growth of the crystals after annealing above the crystallization temperature follows the induced stresses and shell-like structure in the cross section is recognized. [ABSTRACT FROM AUTHOR]

• The magnetooptical contrast on microwires qualitatively changes with rotations of polarizers. • Axially magnetized cylinders may give three types of magnetooptical contrasts. • The presence of a glass coat remarkable reduces a visible portion of a surface. Magneto-optical Kerr effect (MOKE) imaging is a versatile technique for probing a surface magnetization of magnetic materials. Here, we investigate the influence of the polarizers' rotation on the resulting magnetooptical contrast of thin magnetic wires with cylindrical geometry. Employing MOKE microscopy, we image the magnetooptical contrast change and quantify the contribution of the spatially curved cylindrical surface to the overall magnetic contrast. The calculated magnetooptical contrast difference for various extinction angles between polarizer and analyzer provide an estimation of the surface magnetization orientation at curved surfaces. The magnetooptical analysis scheme can be extended to other non-planar magnetic surfaces. [ABSTRACT FROM AUTHOR]

We report time-resolved observations of field-induced domain wall nucleation in asymmetric ferromagnetic rings using single direction field pulses and rotating fields. We show that the asymmetric geometry of a ring allows for controlling the position of nucleation events, when a domain wall is nucleated by a rotating magnetic field. Direct observation by scanning transmission x-ray microscopy (STXM) reveals that the nucleation of domain walls occurs through the creation of transient ripplelike structures. This magnetization state is found to exhibit a surprisingly high reproducibility even at room temperature and we determine the combinations of field strengths and field directions that allow for reliable nucleation of domain walls and directly quantify the stability of the magnetic states. Our analysis of the processes occurring during field induced domain wall nucleation shows how the effective fields determine the nucleation location reproducibly, which is a key prerequisite toward using domain walls for spintronic devices. [ABSTRACT FROM AUTHOR]