Особенности взаимодействия нанокластеров BiFeO-=SUB=-3-=/SUB=-, синтезированных методом растворного горения

The peculiarities presented of the magnetization for BiFeO3 nanoclusters with approximately 50 nm in size. They synthesized under conditions of solution combustion. When synthesized, the magnetic response of nanoclusters differs drastically depending on the type of fuel. If for the case of tartaric acid, the magnetic behaviour of the material follows a model of non-interacting particles, a model of aggregated particles with amorphous or fractal magnetic shell suits the case of sucrose usage.

Accurate Magnetic Shell Approximations with Magnetostatic Finite Element Formulations by a Subdomain Approach

This paper presents a subproblem approach with h-conformal magnetostatic finite element formulations for treating the errors of magnetic shell approximation, by replacing volume thin regions by surfaces with interface conditions. These approximations seem to neglect the curvature effects in the vicinity of corners and edges. The process from the surface-to-volume correction problem is presented as a sequence of several subdomains, which can be composed to the full domain, including inductors and thin magnetic regions. Each step of the process will be separately performed on its own subdomain and submesh instead of solving the problem in the full domain. This allows reducing the size of matrix and time computation.

CO-EXISTENCE OF LOCALIZED MAGNETIC MOMENT AND DELOCALIZED ELECTRONIC SHELL IN SUB-NANOMETER KONDO-LIKE SYSTEMS

Looking for the smallest limit that the Kondo-like effect can be observed has been a long-standing interest in the field of fundamental physics. In this regard, we have investigated the interaction between a countable number of free electrons and a single impurity magnetic moment in two typical quantum systems Cu12Cr and Au19Cr clusters. Both icosahedral Cu12Cr and tetrahedral Au19Cr clusters tend to form a closed-shell electron structure. However, their magnetic moments are completely different. Using density functional theory calculations, we analyzed, discussed and proposed a co-existence picture of electronic and magnetic shell to explain the quenched and unquenched magnetic moment of Cu12Cr and Au19Cr. The finding results are expected to contribute to the understanding of molecular magnetism in bimetallic nanoclusters.

Development of a Novel Latching-Type Electromagnetic Actuator for Applications in Minimally Invasive Surgery

Single-port laparoscopic surgery (SLS), which utilises one major incision, has become increasingly popular in the healthcare sector in recent years. However, this technique suffers from several problems particularly the inability of current SLS instruments to provide the optimum angulation that is required during SLS operations. In this paper, the development of a novel latching-type electromagnetic actuator is reported, which is aimed to enhance the function of SLS instruments. This new actuator is designed to be embedded at selected joints along SLS instruments to enable the surgeon to transform them from their straight and slender shape to an articulated posture. The developed electromagnetic actuator is comprised of electromagnetic coil elements, a solid magnetic shell, and a permanent magnet used to enhance the magnetic field interaction along the force generation path and also to provide the latching effect. In this investigation, electromagnetic finite element analyses were conducted to design and optimise the actuator’s electromagnetic circuit. In addition, the performance of the new actuator was numerically and experimentally determined when output magnetic forces and torques in excess of 9 N and 45 mNm, respectively together with an angulation of 30° were achieved under a short pulse of current supply to the magnetic circuit of the actuator.

ULF waves registered with the Ekaterinburg radar: Statistical analysis and case studies

<p>A midlatitude coherent decameter radar installed near Ekaterinburg, Russia (EKB radar) has been operating since 2012. It is aimed at monitoring dynamics of the ionosphere–magnetosphere system in Eastern Siberia. A special operation mode is used at the radar to study ULF wave activity: three adjacent beams oriented approximately along the magnetic meridian are surveyed with time resolution of 18 s each. A number of wave observation events registered with the radar was analyzed and discussed in several papers. An overview of the main results from these studies is presented here.</p><p>A statistical study of more than 30 waves observed in the nightside ionosphere revealed that in the majority of the cases their frequencies are considerably lower than those of field line resonance (FLR) for appropriate magnetic shells and longitudinal sectors (FLR fundamental frequencies for each case were estimated based on spacecraft data). Thus, these waves cannot be associated with the Alfvén mode. It was assumed that at least part of them should be identified with the drift compressional mode. Indeed, in individual cases oscillations exhibited signatures of this mode: in one of the events a linear dependence of frequency on azimuthal wave number <em>m</em> at a fixed magnetic shell was found. Only the drift compressional mode can feature such dependence in the inner magnetosphere. For two other cases merging of drift compressional and Alfvén modes at some critical value of <em>m</em> was shown. A case of simultaneous spacecraft and radar wave observation accompanied by increases in energetic particle fluxes was shown. A modulation with the frequency of this wave was found for flux intensity of those energetic protons, whose phase velocity is close to that of the wave. This implies that the source of the wave was a drift resonance with the substorm injected protons.</p>

Magnetic Shell Structure of 2D-Trapped Fermi Gases in the Flat-Band Lieb Lattices

We investigate the magnetic shell structure of repulsively interacting two-component Fermi gases trapped in a two-dimensional harmonic potential and loaded on the optical Lieb lattices. We employ the real-space dynamical mean-field theory (R-DMFT) to explicitly consider the trap potential in a self-consistent way. Computing the profiles of particle density and local magnetization across the lattice sites in the trap, we find that the incompressible core with ferrimagnetic ordering appears with the density plateau at the trap center, which is surrounded by the shell of the normal metallic phase. We examine the incompressibility of the core by adding more particles and creating the higher spin-population imbalance. While the core area expands from the outer shell with added particles and increased polarization, the excess particles are prohibited from going inside the core, and thus the density plateau is unchanged at the half-filling with the same magnetic ordering. In addition, we find that the feature of the phase separation differs with the sublattices, where the interstitial sites causing the flat band dispersion shows the signature of the abrupt transition in the density and magnetization at the boundary between the core and surrounding shells.