2021, Zubar, T., Grabchikov, S., Kotelnikova, A., Kaniukov, E., Kutuzau, M., Leistner, K., Nielsch, K., Vershinina, T., Tishkevich, D., Kanafyev, O., Kozlovskiy, A., Zdorovets, M., Fedosyuk, V., Trukhanov, A.

The effect of microstructure on the efficiency of shielding or shunting of the magnetic fluxby permalloy shields was investigated in the present work. For this purpose, the FeNi shieldingcoatings with different grain structures were obtained using stationary and pulsed electrodeposition.The coatings’ composition, crystal structure, surface microstructure, magnetic domain structure, andshielding efficiency were studied. It has been shown that coatings with 0.2–0.6μm grains have adisordered domain structure. Consequently, a higher value of the shielding efficiency was achieved,but the working range was too limited. The reason for this is probably the hindered movement of thedomain boundaries. Samples with nanosized grains have an ordered two-domain magnetic structurewith a permissible partial transition to a superparamagnetic state in regions with a grain size of lessthan 100 nm. The ordered magnetic structure, the small size of the domain, and the coexistenceof ferromagnetic and superparamagnetic regions, although they reduce the maximum value ofthe shielding efficiency, significantly expand the working range in the nanostructured permalloyshielding coatings. As a result, a dependence between the grain and domain structure and theefficiency of magnetostatic shielding was found.

2019, Patra, Rajkumar, Mattheis, Roland, Stöcker, Hartmut, Monecke, Manuel, Salvan, Georgeta, Schäfer, Rudolf, Schmidt, Oliver G., Schmidt, Heidemarie

The magnetooptical (MO) response of Ru/Py/Ta thin film stacks with 4, 8, and 17 nm thick Ni81Fe19 permalloy (Py) films on a SiO2/Si and a ZnO substrate was measured by vector magnetooptical generalized ellipsometry. The MO response from VMOGE was modelled using a 4  ×  4 Mueller matrix algorithm. The wavelength-dependent, substrate-independent and thickness-independent complex MO coupling constant (Q) of Py in the Ru/Py/Ta thin film stacks was extracted by fitting Mueller matrix difference spectra in the spectral range from 300 nm to 1000 nm. Although the composition-dependent saturation magnetization of NixFe1−x alloys (x  =  0.0...1.0), e.g. of Ni81Fe19, is predictable from the two saturation magnetization end points, the MO coupling constant of NixFe1−x is not predictable from the two Q end points. However, in a small alloy range (0.0  <  x  <  0.2 and 0.8  <  x  <  1.0) the composition-dependent Q of NixFe1−x can be interpolated from a sufficiently high number of analyzed NixFe1−x alloys. The available complex MO coupling constants of six different NixFe1−x (x  =  1.0 to 0.0) alloys were used to interpolate MO response of binary NixFe1−x alloys in the range from x  =  0.0 to x  =  1.0.