SURVEY OF THE DEPENDENCE ON TEMPERATURE OF THE COERCIVITY OF GARNET-FILMS

The temperature dependence of the domain-wall coercive field of epitaxial magnetic garnets films has been investigated in the entire temperature range of the ferrimagnetic phase, and has been found to be described by a set of parametric exponents. In subsequent temperature regions different slopes were observed, with breaking points whose position was found to be sample dependent. A survey ba.ed on literature Data as well as on a large number of our own samples shows the general existence of this piecewise exponential dependence and the presence of the breaking points. This type of domain-wall coercive field temperature dependence was found in all samples in the large family of the epitaxial garnets (about 30 specimens of more than ten chemical compositionsj and also in another strongly anisotropic material (TbFeCo)

Three-Dimensional Micromagnetic Simulation of Spatial Distribution of Magnetization in Thick Cobalt Layers

Spatial magnetization distribution of cobalt layer is studied by means of three-dimensional micromagnetic simulations in the range of cobalt thickness d from 21 to 249 nm. In this range, a spin-reorientation phase transition occurs, while the cobalt thickness increases, from a state with in-plane magnetization, to a state with out-of-plane components of magnetization. An infinite cobalt layer is modelled by the 750 nm × 750 nm × d structure consisting of cubic cells of size of 3 nm and the periodic boundary conditions. For larger thicknesses, a labyrinth, partially closed, stripe structure has been found

Phase diagram of vortex lattice on a square pinning array in superconducting films

We have analyzed the phase transitions in a square lattice of vortices using the thermodynamic approach. For a square array of the artificially created pin centers in \chem{Nb} superconducting film we have calculated the phase diagram, which reveals the re-entrant melting features. We explain this effect by the nonmonotonic temperature dependence of the vortex-vortex interaction potential

Defectors from the Wehrmacht at the Soviet-German Front in 1941–1943 (on the problem statement)

The article examines the phenomenon of the “deserters of the flag,” i.e. the defection of the Wehrmacht soldiers to the Red Army. The chronological scope of the article is limited to the period between 1941 and 1943, which is due to the existence of a significant number of archival documents that contain information about the facts of deflection of the enemy’s military personnel to the Red Army during this specific period in the fonds of the Central Archive of the Ministry of Defense of the Russian Federation (TsAMO) as well as the corresponding captured Wehrmacht documents stored in the US National Archives. This circumstance allows us to compare the attitude of the warring parties to the phenomenon under study. In particular, the questionnaires filled in by the Soviet side for prisoners of war necessarily contained information about voluntary surrender or defection to the Red Army. Based on the analysis of documents from Russian and foreign archives, the number of defectors was determined and the motives for such a strategy of behavior of military personnel of the German army and its allies were identified. It is noted that instances of defection of Wehrmacht military personnel to the enemy’s side were recorded even during the period of the most successful German operations in 1941–42. It is emphasized that the number of defectors increased significantly during any crises at the Eastern Front. According to the authors, when the decision to cross the front line was made, personal rather than ideological motives played the main role. A significant part of the Wehrmacht defectors included military personnel of non-German ethnicity, who were less resistant to the effects of unfavorable developments at the front

Effects of High Magnetic Fields on the Diffusion of Biologically Active Molecules

The diffusion of biologically active molecules is a ubiquitous process, controlling many mechanisms and the characteristic time scales for pivotal processes in living cells. Here, we show how a high static magnetic field (MF) affects the diffusion of paramagnetic and diamagnetic species including oxygen, hemoglobin, and drugs. We derive and solve the equation describing diffusion of such biologically active molecules in the presence of an MF as well as reveal the underlying mechanism of the MF’s effect on diffusion. We found that a high MF accelerates diffusion of diamagnetic species while slowing the diffusion of paramagnetic molecules in cell cytoplasm. When applied to oxygen and hemoglobin diffusion in red blood cells, our results suggest that an MF may significantly alter the gas exchange in an erythrocyte and cause swelling. Our prediction that the diffusion rate and characteristic time can be controlled by an MF opens new avenues for experimental studies foreseeing numerous biomedical applications

Magnetic Heating by Tunable Arrays of Nanoparticles in Cancer Therapy

Detailed knowledge about the temperature distribution achieved in the target area is essential for the development of magnetic hyperthermia treatments. However, the temperature inhomogeneity was found in all local hyperthermia studies. As a consequence of the impossibility of guaranteeing the temperature and thus the thermal dose distribution, hyperthermia is never applied as a single treatment modality. We suggest a model that enables the calculations and optimization of the spatial-time distribution of the temperature in the target volume (i.e. tumor) caused by magnetically heated elements: (i) arrays of clusters of iron oxides magnetite $(Fe_3O_4)$ magnetic nanoparticles, and (ii) arrays of magnetic needles. In order to find the spatial-time temperature distribution in tumor, the bioheat transfer equation is solved for the two above-mentioned arrays of magnetically heated sources embedded in the tumor. The temporal and spatial temperature distributions were calculated with regard to the effect of blood perfusion in the tumor. It is shown that a matrix of magnetic micro-needles injected in the tumor could provide rather uniform tumor heating with the center-edge temperature difference smaller than 3°C at any times during the magnetic hyperthermia treatments. The temperature profiles can be suitably adjusted by a proper choice of the magnetic nanoparticles arrangement