Superparamagnetic iron oxide nanoparticles (SPIONs) are promising drug delivery carriers and hyperthermia agents for the treatment of cancer. However, to ensure their safety in vivo, SPIONs must be modified in order to prevent unwanted iron release. Thus, SPIONs were coated with silica layers of different morphologies: non-porous (@SiO₂), mesoporous (@mSiO₂) or with a combination of non-porous and mesoporous layers (@SiO₂@mSiO₂) deposited via a sol–gel method. The presence of SiO₂ drastically changed the surface properties of the nanoparticles. The zeta potential changed from 19.6 ± 0.8 mV for SPIONs to −26.1 ± 0.1 mV for SPION@mSiO₂. The Brunauer–Emmett–Teller (BET) surface area increased from 7.54 ± 0.02 m²/g for SPIONs to 101.3 ± 2.8 m²/g for SPION@mSiO₂. All types of coatings significantly decreased iron release (at least 10 fold as compared to unmodified SPIONs). SPIONs and SPION@mSiO₂ were tested in vitro in contact with human lung epithelial cells (A549 and BEAS-2B). Both nanoparticle types were cytocompatible, although some delay in proliferation was observed for BEAS-2B cells as compared to A549 cells, which was correlated with increased cell velocity and nanoparticles uptake.

We have studied the transition between two different magnetization reversal mechanisms for thin Co/Pd multilayers with perpendicular magnetic anisotropy, appearing in magnetic dot and antidot arrays, which were prepared by nanosphere lithography. Various ordered arrays of nanostuctures, both magnetic dots and antidots, were created by varying size and distance between the nanospheres employing RF-plasma etching. We have shown that the coercivity values reach a maximum for the array of antidots with a separation length close to the domain wall width. In this case, each area between three adjacent holes corresponds to a single domain configuration, which can be switched individually. On the contrary, small hole sizes and large volume of material between them results in domain wall propagation throughout the system accompanied by strong domain wall pinning at the holes. We have also shown the impact of edge effects on the magnetic anisotropy energy.

Ordered FePdCu nanoisland arrays were formed by annealing at 600 °C, which caused solid state dewetting of [Cu/Fe/Pd] multilayers deposited on self-assembled SiO ₂ nanospheres with a size of 100 nm. A single FePdCu island was formed on the top of each SiO ₂ nanosphere. The structure of the obtained system was studied by x-ray diffraction (XRD), while its magnetic properties were studied by SQUID magnetometry. A partially ordered L1 ₀ alloy appeared in the annealed films, leading to magnetic hardening of the material. The paper presents the influence of the patterning on the system properties. It is shown that templated dewetting is a method providing nanoislands with well-controlled sizes and positions. The role of copper admixture in controlling the structural and magnetic properties is also discussed.

Magnetic properties of the Mott insulator with the pyrochlore structure ${\mathrm{Y}}_2{\mathrm{Ru}}_2{\mathrm{O}}_7$ were investigated using ${}^{99}\mathrm{Ru}$ Mössbauer spectroscopy. Bulk magnetization measurements confirmed appearance of the spin-glass-like antiferromagnetic order with very large differences between zero-field-cooled and field-cooled magnetizations below the Néel temperature $T_N=76\left(2\right)\mathrm{K}$. The Mössbauer spectra were obtained above and below $T_N$. Analysis of the spectrum recorded at $4.2\mathrm{K}$ suggested a noncollinear local ordering of ruthenium magnetic moments. The electronic structure of the individual ruthenium ion, responsible for magnitudes of hyperfine parameters and the ruthenium magnetic moment, was discussed within the framework of the crystalline electric-field model, including the spin-orbit coupling and the exchange interaction in the molecular-field approximation. Reasonably good agreement between calculated and experimentally determined parameters was obtained. Simultaneously, the experimentally observed easy plane of ruthenium magnetic moments was explained.

A development of modern spintronic devices requires materials exhibiting specific magnetic effects. In this paper, we investigate a magnetization reversal mechanism in a [Co/Pd_x]₇/CoO/[Co/Pd_y]₇ thin film composite where an antiferromagnet is sandwiched between a hard and a soft ferromagnets with different coercivities. The antiferromagnet/ferromagnet interfaces give rise to the exchange bias effect. The application of soft and hard ferromagnetic films causes exchange-spring-like behavior while the choice of the Co/Pd multilayers provides large out-of-plane magnetic anisotropy. We observed that the magnitude and the sign of the exchange bias anisotropy field are related to the arrangement of the magnetic moments in the antiferromagnetic layer. This ordering is induced by the spin orientation present in neighboring ferromagnetic films which is, in turn, dependent on the orientation and strength of the external magnetic field.