The origin of anomalous negative magnetoresistance and its temperature dependence in polycrystalline $\mathrm{Ni}–\mathrm{Mn}–\mathrm{Ga}$ films prepared by pulse laser deposition was studied. The investigation of structural, transports, magnetic, and ferromagnetic resonance properties of the films suggests contributions of different mechanisms in magnetotransport. At low magnetic fields the main contribution to magnetoresistance is due to the transport between the areas with different orientation of magnetic moments, while at high fields it is an electron scattering of in spin-disordered areas.

Optical properties of ferromagnetic half-metallic full-Heusler Co2FeGe alloy are investigated experimentally and theoretically. Co2FeGe thin films were obtained by DC magnetron sputtering and show the saturation magnetization at T = 10 K of m≈5.6μB/f.u., close to the value predicted by the Slater-Pauling rule. First-principles calculations of the electronic structure and the dielectric tensor are performed using the full-potential linearized-augmented-plane-wave method in the generalized gradient approximation (GGA) and GGA + U approximation. The measured interband optical conductivity spectrum for the alloy exhibits a strong absorption band in the 1–4 eV energy range with pronounced fine structure, which agrees well with the calculated half-metallic spectrum of the system, suggesting a near perfect spin-polarization in the material.

A series of $({\mathrm{Co}}_{50}{\mathrm{Fe}}_{50}{)}_x\mathrm{-(}{\mathrm{Al}}_2{\mathrm{O}}_3{)}_{\text{1−x}}$ cermet granular thin films deposited on glass substrates by dual electron beam evaporation was studied for their structural, magnetotransport, and magnetic properties. Upon varying the magnetic volume fraction, x, from 0.07 to 0.52 the percolation threshold ${\mathrm{(x}}_c)$ was determined from resistivity measurements to be ∼0.17. This value agrees well with the theoretical prediction for a three-dimensional system of spherical particles. Values of the isotropic tunneling magnetoresistance (TMR) as high as 10% at room temperature were found for films with $\text{x<0.16.}$ The relationship between magnetotransport (maximum TMR) and the granular film topology (the percolation threshold) is discussed.

Granular multilayers ${[\mathrm{Fe}\left(t\mathrm{nm}\right)∕\mathrm{Mg}\mathrm{O}\left(3\mathrm{nm}\right)]}_N$ with $0.4\mathrm{nm}⩽t⩽1.5\mathrm{nm}$ were prepared by sequential pulsed laser deposition. Transmission electron microscopy (TEM) images show that increasing $t$ causes the growth of the sizes of Fe nanoparticles and broadening of the particle size distribution. For $t>0.81\mathrm{nm}$ , continuous Fe layers are formed. The evolution of the shapes and sizes of the particles is reflected in the magnetic properties of the investigated films. A crossover from superparamagnetic to ferromagnetic behavior upon formation of a continuous Fe layer is observed. The fit of zero field cooled and field cooled susceptibility measurements and magnetization curves using Curie–Weiss law and a weighted sum of Langevin functions, respectively, allows the estimation of the average granule size for the films with $t<0.61\mathrm{nm}$ . The results of the estimations correlate with the data obtained from TEM images. Reduction of saturation magnetization for Fe nanoparticles and an increase of the coercivity up to $1200\mathrm{Oe}$ at low temperatures were found. It is attributed to the formation of Fe-core∕$\mathrm{Fe}{\mathrm{O}}_x$ -shell structured nanocrystals. The oxide shell gives rise to a strong contribution of surface anisotropy. Isotropic tunneling magnetoresistance up to $\sim 3\%$ at room temperature and in magnetic field up to $18\mathrm{kOe}$ was found for the film with $t=0.61\mathrm{nm}$ . For higher $t$ , an anisotropic magnetoresistance typical for continuous ferromagnetic films was observed.

Regular nanosized structures are considered to be promising materials for magnetic information storage media with high density of information. Recently attention was paid to static and dynamic magnetic properties arising from dimensional confinement in such nanostructures. Here we present an investigation of permalloy antidot arrays of different thicknesses. Thin permalloy films of thickness ranging from $10\text{to}500\mathrm{nm}$ were deposited on nanoporous ${\mathrm{Al}}_2{\mathrm{O}}_3$ membranes with a pore size of $100\mathrm{nm}$ . It was found that additional ferromagnetic resonance peaks appear for film thicknesses below $100\mathrm{nm}$ , while films with larger thicknesses show resonance properties similar to continuous films. A comparison between the films deposited onto Si wafers and porous media was done. An evolution of the domain structures observed in MFM experiments was confirmed by micromagnetic calculations.