Oksana Gorobets

Goos–Hänchen Shift of a Spin-Wave Beam at the Interface Between Two Ferromagnets

Spin waves (SWs) are promising information carriers which can be used in modern magnonic devices, characterized by higher performance and lower energy consumption than presently used electronic circuits. However, before practical application of SWs, the efficient control over SW amplitude and phase needs to be developed. We analytically analyze reflection and refraction of the SWs at the interface between two ferromagnetic (FM) materials. In the model, we consider the system consisting of two semi-infinite FM media, separated by the ultra-narrow interface region with the magnetic anisotropy. We have found the Goos–Hänchen (GH) shift for SWs in transmission and reflection, and performed detailed investigations of its dependence on the anisotropy at the interface and materials surrounding the interface. We have demonstrated the possibility of obtaining GH shift of several wavelengths in reflection for realistic material parameters. That proves the possibility for change of the SWs phase in FM materials at sub-wavelength distances, which can be regarded as a metasurface for magnonics.

Роль патогенних мікроорганізмів у накопиченні біогенних магнітних наночастинок у тканинах легень

Purpose: In this paper the role of pathogenic microorganisms in the accumulation of biogenic magnetic nanoparticles in lung tissues is examined. The main purpose of the present research is to prove that biogenic magnetic nanoparticles can be accumulated in lung tissues because of the pathogenic microorganisms during lung disease. Methods: Pairwise and multiple alignment of amino acid sequences, electron paramagnetic resonance. Results: The producers of biogenic magnetic nanoparticles were found among pathogenic microorganisms that cause lung disease. Biogenic magnetic nanoparticles can be accumulated in lung tissues because of these pathogenic microorganisms during relevant lung diseases. The presence of biogenic magnetic nanoparticles in lung tissues was proved using the electron paramagnetic resonance spectra analysis. Discussion: The results of the present research can be used to understand the possible reasons of toxic and allergic effects and even corking of vessels during uncontrolled accumulation of magnetic nanoparticles in different organs and tissues because of their magnetic dipole-dipole interaction with biogenic magnetic nanoparticles on cell membranes and to prevent it.

Boundary conditions at the interface of finite thickness between ferromagnetic and antiferromagnetic materials

Abstract Systematic approach has been applied to obtain the boundary conditions for magnetization at an interface between ferromagnetic (FM) and antiferromagnetic (AFM) materials in the continuous medium approximation. Three order parameters are considered inside an interface of finite thickness magnetization M of FM, magnetizations of both sublattices M1 and M2 of AFM. The boundary conditions are defined in terms of some average properties of the FM/AFM interface. The interface has a finite thickness which is much less than spin wave length. This approach allowed to take into account the interface anisotropy, interface symmetric exchange coupling and interface coupling resulting from inversion symmetry breaking in the vicinity of the interface.

Goos-Hänchen shift of a spin-wave beam in transmission through interface between two ferromagnets

The main object of investigation in magnonics, spin waves (SWs) are magnetization excitations propagating without charge transport.

Physiological origin of biogenic magnetic nanoparticles in health and disease: from bacteria to humans

The discovery of biogenic magnetic nanoparticles (BMNPs) in the human brain gives a strong impulse to study and understand their origin. Although knowledge of the subject is increasing continuously, much remains to be done for further development to help our society fight a number of pathologies related to BMNPs. This review provides an insight into the puzzle of the physiological origin of BMNPs in organisms of all three domains of life: prokaryotes, archaea, and eukaryotes, including humans. Predictions based on comparative genomic studies are presented along with experimental data obtained by physical methods. State-of-the-art understanding of the genetic control of biomineralization of BMNPs and their properties are discussed in detail. We present data on the differences in BMNP levels in health and disease (cancer, neurodegenerative disorders, and atherosclerosis), and discuss the existing hypotheses on the biological functions of BMNPs, with special attention paid to the role of the ferritin core and apoferritin.

Nonlinear spin wave excitation at the interface between two ferromagnets with broken spatial inversion symmetry

In this paper we consider the system of two ferromagnets semi-infinite media with interface in which spatial inversion symmetry is broken. We obtain the boundary conditions for interface of this model materials. The possibility of nonlinear spin wave formation at transmission of a spin wave through the boundary of two ferromagnets with spatial inversion broken symmetry was shown.

ANALYSIS OF EFFECTIVNESS OF MAGNETICALLY LABELED BIOSORBENT OBTAINED THROUGH THE MECHANICAL AND MAGNETOHYDRODYNAMIC STIRRING

The efficiency of Cu 2+ ion extraction of magnetically labeled biosorbent based on yeast Sacharomyces cerevisiae obtained by magnetohydrodynamic stirring in combined magnetic and electric fields has been determined. The effect of different concentration of magnetic nanoparticles and yeast cells on the magnetic susceptibility was determined. Optimal magnetite content is 1 %, as such biosorbent has a maximum magnetic susceptibility and the best stability. The higher sorption capacity is observed for magnetically labeled biosorbent obtained through the magnetohydrodynamic stirring in the combined magnetic and electric field with concentration of magnetite 1 %. The process of active and passive biosorption shows that part of the magnetite nanoparticles has been attached to the surface of biosorbent. This indicates that both passive and active sorption takes place in the process of interaction of yeast cells and magnetite nanoparticles.

Фрактальна розмірність резистентних та чутливих до доксорубіцину клітин раку молочної залози, експонованих у магнітному полі

У роботі досліджується фрактальна розмірність резистентних та чутливих до дії доксорубіцину клітин раку молочної залози, експонованих у магнітному полі. Виявлено, що резистентні та чутливі до дії доксорубіцину клітини раку молочної залози лінії MCF мають різне значення фрактальної розмірності. Таким чином, головна мета цього дослідження полягає в перевірці можливості використання фрактальної розмірності як маркеру для визначення чутливості до дії доксорубіцину клітин раку молочної залози лінії MCF, експонованих у магнітному полі.