Interaction Of Magnetic Field Research Articles

Nontrivial effect of dephasing: Enhancement of rectification of spin current in graded XX chains.

In order to reveal mechanisms to control and manipulate spin currents, we perform a detailed investigation of the dephasing effects in the open XX model with a Lindblad dynamics involving global dissipators and thermal baths. Specifically, we consider dephasing noise modeled by current-preserving Lindblad dissipators acting on graded versions of these spin systems, that is, systems in which the magnetic field and/or the spin interaction are growing (decreasing) along the chain. In our analysis, we study the nonequilibrium steady state via the covariance matrix using the Jordan-Wigner approach to compute the spin currents. We find that the interplay between dephasing and graded systems gives rise to a nontrivial behavior: When we have homogeneous magnetic field and graded interactions we have rectification enhancement mechanisms, and when we have fully graded systems we can control the spin current in order to keep the direction of the particle and/or spin flow even with inverted baths. We describe our result in detailed numerical analysis and we see that rectification in this simple model indicates that the phenomenon may generally occur in quantum spin systems.

Increasing the accuracy of measuring the physicochemical parameters of wastewater samples when implementing a new informative method

Increasing the accuracy of measuring the physicochemical parameters of wastewater samples when implementing a new informative method

Effects of extremely low frequency electromagnetic fields on the tumor cell inhibition and the possible mechanism

Low-frequency magnetic fields exert a significant inhibitory effect on tumor growth and have been developed as a therapeutic modality. However, the effect of a low-frequency magnetic field on the interaction between cells is still poorly understood. This study aimed to preliminarily evaluate the direct effect of magnetic field ditectely on cultured cells and indirect effect mediated by cell-environment (conditioned medium). 293 T cells, Hepg2 cells, A549 cells have been cultured at 37 ± 0.18 °C in presence of an extremely low-frequency magnetic field of 20 Hz, 5-mT. The adherent tumor cells were more sensitive to magnetic field inhibition in the original environment (conditioned medium) with adherence inhibition rate for Hepg2 and A549 estimated at 18% and 30% respectively. The inhibition effect was suppressed when the suspended cells separated or clump density at a low density. The nontumor cell lines showed no inhibitory effect on exposure to a low-frequency magnetic field. The intracellular ion fluorescence (IIF) showed that the magnetic field significantly altered the membrane potential, indicating hyperpolarization of the adherent cells (ΔIIF 293 T cells: − 25%, ΔIIF Hepg2 cells: − 20% and ΔIIF A549 cells: − 13%) and depolarization of the suspended cells (ΔIIF Raji cells: + 9%). In addition, the conditioned media collected after magnetic field exposure acted on unexposed tumor cells and caused inhibition. Our findings might provide a basis for the mechanism of magnetic field interaction between cells and cell environment in the future.

Effect of the Dzyaloshinskii-Moriya interaction on quantum speed limit and orthogonality catastrophe

We study the effect of the Dzyaloshinskii-Moriya (DM) interaction on the quantum speed limit (QSL) and orthogonality catastrophe (OC) in XY spin chains. With an initial sudden quench, the general expressions of fidelity and QSL time are derived in terms of the antisymmetric quasiparticle excitation spectra. The numerical and analytical studies show that depending on the system parameters, the DM interaction has various influences on QSL and fidelity. In general, the OC is witnessed and QSL time vanishes in the thermodynamic limit as the variance of the quenched Hamiltonian in ground states scales with the system size, and the conclusion is independent of the DM interaction strength. However, it is interesting to note that the QSL can uniquely detect the critical points and lines induced by the DM interaction. We further analyze the actual evolution speed, a measure of the criticality, and find its direct correspondence with the OC. We also study an interesting phenomenon arising from the magnetic field and DM interaction in the presence of classical noise. Notably, we find that the system dynamic is fault tolerant when the system is subject to a uniform classical noise in the DM interaction strength.

Robustness of the Skyrmion Phase in a Frustrated Heisenberg Antiferromagnetic Layer against Lattice Imperfections and Nanometric Domain Sizes

By employing GPU-implemented hybrid Monte Carlo simulations, we study the robustness of the skyrmion lattice phase (SkX) in a frustrated Heisenberg antiferromagnetic (AFM) layer on a triangular lattice with a Dzyaloshinskii–Moriya interaction in the external magnetic field against the presence of lattice imperfections (nonmagnetic impurities) and lattice finiteness. Both features are typical of experimentally accessible magnetic materials and require theoretical investigation. In the pure model of infinite size, SkX is known to be stabilized in a quite wide temperature-field window. We first study the effects of such imperfections on the SkX stability and compare them with those in the nonfrustrated ferromagnetic counterpart. The partial results of this part appeared in the conference proceedings [M. Mohylnaand M. Žukovič, Proceedings of the 36th International ECMS International Conference on Modelling and Simulation, ECMS, 2022]. We further look into whether SkX can also persist in finite clusters, i.e., zero-dimensional systems of nanometric sizes. In general, both the presence of magnetic vacancies as well as the finiteness of the system tend to destabilize any ordering. We show that in the present model, SkX can survive, albeit in a somewhat distorted form, in the impure infinite system up to a fairly large concentration of impurities, and, in the pure finite systems, down to sizes comprising merely tens of particles. Distortion of the SkX phase due to the formation of bimerons, reported in the ferromagnetic model, was not observed in the present frustrated AFM case.

Editorial

Editorial

Physicochemical insight into the metal atom effect on magnetocaloric behavior of paramagnetic metalloporphyrins

To reveal the effect of coordinated organic and inorganic σπ-ligands on the magnetocaloric properties of metal ions at room temperature, we have synthesized paramagnetic (5,10,15,20-tetraphenylporphinato)cobalt(II), (chloro)(2,3,7,8,12,13,17,18-octaethylporphinato))manganese(III), their coordination complexes with 1-methyl-2-(pyridin-4′-yl)-3,4-fullero[60]pyrrolidine (1:3 and 1:2, respectively), and (ethoxy)(oxo)(5,10,15,20-tetraphenylporphinato)molybdenum(V) and have fully characterized their chemical structure by UV–vis, IR, 1H NMR, MALDI TOF spectral methods. Using the direct microcalorimetric method and DSC we have obtained, respectively, magnetocaloric effect, heat, change of enthalpy/entropy during the magnetization over the temperature range of 285 – 338 K in magnetic fields from zero to 1 T and the specific heat capacities in the temperature range from 270 to 400 К in zero fields for paramagnets synthesized. Involving the results of DFT calculations, we have shown that the electron structure of a central metal atom is the determining factor in the positive magnetocaloric effect in the complexes studied. The decrease in the MCE value is observed in the case of the intramolecular antiferromagnetic interactions in external magnetic fields (manganese(III) complexes) and additional axial bonding of the bulk fullerene-containing base.

Editorial: Interactions of magnetic fields with living cells

Editorial: Interactions of magnetic fields with living cells

Upstream Shift of Generation Region of Whistler‐Mode Rising‐Tone Emissions in the Magnetosphere

AbstractWe have performed a series of simulation runs for whistler‐mode wave‐particle interaction in a parabolic magnetic field with 12 different frequencies of triggering waves and 3 different plasma frequencies specifying cold plasma densities. Under a given plasma condition, a specific frequency range of the triggering wave exists that can generate rising‐tone emissions. The generation region of rising‐tone emission shifts upstream. The velocity of the wave generation region is dependent on duration of the subpacket, which is controlled by the formation of the resonant current in the generation region. When the source velocity, which is a sum of the resonance and group velocities, is approximately the same as the velocity of the wave generation region, a long‐sustaining rising‐tone emission is generated. When the spatial and temporal gap between subpackets exists due to damping phase of short subpacket generation, resonant electrons in the gap of the subpackets are carried at the resonance velocity to the upstream region, and the velocity of the wave generation region becomes large in magnitude. When formation of resonant currents is delayed, the velocity of the generation region becomes smaller than the source velocity in magnitude. Below one quarter of the cyclotron frequency, coalescence of subpackets takes place, suppressing formation of the resonant current in the generation region. Since gradual upstream shift of the generation region is necessary for the wave to grow locally, the source velocity should be a small negative value.

Electromagnetic analysis of the Interspace Afocal Module of the Wide Angle Viewing System diagnostic for ITER

The ITER Visible and Infrared Wide Angle Viewing System (WAVS) is a diagnostic aiming to optically monitor the tokamak first wall and divertor for machine protection, plasma control and physics analysis. The Interspace Afocal Module (IAM) is a refractive optical system, being one of the WAVS components located in the Interspace area.In order to assure the optical performance, the IAM has to withstand all the relevant loads defined for the Final Design, including the electromagnetic (EM) loads developed in the Interspace area under EM events. Volumetric forces during transient EM events arise from the interaction of the background magnetic field with the eddy currents induced in the conductive components when they experience time-varying magnetic fields. In case of Category III and IV loads, including load combinations with certain Major Disruption and Vertical Displacement Event cases, the IAM integrity has to be ensured since its structure is classified as Safety Relevant.The EM volumetric loads are calculated through a 3D Finite element model and will serve as inputs for the later structural analysis. The paper summarizes the EM analysis of the IAM, performed by CIEMAT, to validate its Final Design.

Dynamic resistance and total loss in small REBCO pancake and racetrack coils carrying DC currents under an AC magnetic field

In many high-temperature superconducting applications, REBCO (Rare-earth barium copper oxide) coils carry DC currents under AC magnetic fields, such as the field winding of rotating machines, linear synchronous motors and the electro-dynamic suspension system of maglev. In such operating conditions, REBCO coils generate AC loss—total loss which includes the magnetization loss due to the shielding currents, and the dynamic loss arising from dynamic resistance caused by the interaction of DC currents and AC magnetic fields. In this work, dynamic resistance and total loss in a small double pancake coil (DPC) and a small double racetrack coil (DRC) are investigated via experiments in the temperature range between 77 K and 65 K. The DC currents are varied from zero to 70% of the self-field critical currents of the REBCO coils, with AC magnetic fields up to 100 mT. The experimental results in the DPC are well supported by the finite element simulation results using 3D T-A formulation. Our results show that the critical current of the DRC is approximately 2%–5% higher than that of the DPC in the temperature range. For given experimental conditions, the magnetization loss in both coils is much greater than the dynamic loss. The dynamic loss and magnetization loss in the DRC are greater than those in the DPC, which we attribute to the large perpendicular magnetic field component in the straight sections of the DRC.

Particle-In-Cell Simulations of High Efficiency 12-Vanes 2.45 GHz Continuous Wave Magnetron

As an essential vacuum electronic device for producing the microwave, the magnetron has various applications. This study developed a novel high-efficiency 12-vanes CW magnetron and anode resonance system that improved mode separation, expanded the working space of π-mode and made other modes more challenging to trigger, ultimately eliminating the possibility of mode jumping. A magnetron was simultaneously supplied with a particular quantity of anode voltage, and the cathode was generated by the electron, and high-frequency field interaction of a homogeneous magnetic field. The work efficiency of the 12-vanes CW magnetron was significantly enhanced. Given an anode voltage of 8000 V and a magnetic flux density of 3980 Gs as a consequence of particle simulation, the variation trend of a magnetron’s output power oscillation curve correlated with the development of hexagonal spokes. After a period of stable operation, the magnetron’s fundamental parameters were determined to be as follows: the primary frequency oscillation frequency was 2.466 GHz, the anode collision current was 1.08 A, the amplitude of sinusoidal oscillation was 125, the output power was 7812.5 W, and the corresponding power conversion efficiency was 90.42%. Changing the magnitude of the anode voltage or magnetic flux density resulted in a reduction in power conversion efficiency within a particular range; however, between 85% and 90% stability was maintained.

Interaction of magnetic fields with biogenic magnetic nanoparticles on cell membranes: Physiological consequences for organisms in health and disease

The interaction mechanisms between magnetic fields (MFs) and living systems, which remained hidden for more than a hundred years, continue to attract the attention of researchers from various disciplines: physics, biology, medicine, and life sciences. Revealing these mechanisms at the cellular level would allow to understand complex cell systems and could help to explain and predict cell responses to MFs, intervene in organisms’ reactions to MFs of different strengths, directions, and spatial distributions. We suggest several new physical mechanisms of the MF impacts on endothelial and cancer cells by the MF interaction with chains of biogenic and non-biogenic magnetic nanoparticles on cell membranes. The revealed mechanisms can play a hitherto unexpected role in creating physiological responses of organisms to externally applied MFs. We have also a set of theoretical models that can predict how cells will individually and collectively respond to a MF exposure. The physiological sequences of the MF – cell interactions for organisms in health and disease are discussed. The described effects and their underlying mechanisms are general and should take place in a large family of biological effects of MFs. The results are of great importance for further developing novel approaches in cell biology, cell therapy and medicine.

Sunspots and their cycle

These dark blemishes on stars are key to understanding the interaction of strong magnetic fields and dynamic plasma.

Many-body localization in the random-field Heisenberg chain with Dzyaloshinskii-Moriya interaction

We study the one-dimensional spin-1/2 Heisenberg chain with Dzyaloshinskii-Moriya interaction in a random magnetic field using exact diagonalization. In order to obtain many-body mobility edge at infinite temperature, we employ a polynomial filtered Lanczos method that can avoid the fill-in problem when implementing the commonly used shift-and-invert transformation. In stark contrast to the original Heisenberg model, although the localized phase always conforms to Poisson statistics, the ergodic phase exhibits the Gaussian unitary ensemble rather than the Gaussian orthogonal ensemble statistics due to the lack of complex conjugation symmetry. The boundary between the ergodic and localized phases is determined by carefully performing finite-size scalings for the level statistics, entanglement entropy and its standard deviation, as well as fluctuations of the total spin of the system. The two phases are also well distinguished by the full delocalization or localization in the Hilbert space wherein the participation entropies present. To indicate the localized phase in experiment, we propose a scheme for realizing the out-of-time-order correlator on a modern nuclear magnetic resonance quantum simulator.

Ground-Based Experiment for Electric Propulsion Thruster Plume—Magnetic Field Interaction

Electric space propulsion is a technology which is employed on a continuously increasing number of spacecrafts. While the current focus of their application area is on telecommunication satellites and on space exploration missions, several new ideas are now discussed that go even further and apply the thruster plume particle flow for transferring momentum to targets such as space debris objects or even asteroids. In these potential scenarios, the thruster beam impacts on distant objects and subsequently generates changes in their flight path. One aspect which so far has not been systematically investigated is the interaction of the charged particles in the propulsion beam with magnetic fields which are present in space. This interaction may result in a deflection of the particle flow and consequently affect the aiming strategy. In the present article, basic considerations related to the interaction between electric propulsion thruster plumes and magnetic fields are presented. Experiments with respect to these questions were conducted in the high-vacuum plume test facility for electric thrusters (STG-ET) of the German Aerospace Center in Göttingen utilizing a gridded ion thruster, an RIT10/37, and a Helmholtz coil to generate magnetic fields of varying field strength. It was possible to detect a beam deflection on the RIT ion beam caused by a magnetic field with an Earth-like magnetic field strength.

Mitigation of Insulator Lightning-Induced Voltages by Installing Parallel Low-Voltage Surge Arresters

In this paper, we propose a mitigation method for reducing lightning-induced insulator voltages based on the installation of low-voltage surge arresters aligned parallelly to the insulator. The three-dimensional finite-difference time-domain (FDTD) method is applied to numerically model a real surge arrester residual voltage evaluation system. The application of a transient current pulse, typical of lightning discharges, is considered in our numerical model. We considered cases with one or two surge arresters installed per phase, in three different geometric and parametric configurations for installing distribution surge arresters. In addition to the Kirchhoff current division, which reduces both the absorbed energy and the thermal stress, the results associated with the installation of two surge arresters parallelly aligned to the insulator show that the interaction of magnetic fields generated by the surge arresters’ currents can produce an additional strong reduction in lightning-induced voltage over the insulator, as presented in this paper. Conditions for maximum voltage reduction are also identified. A brief cost-effectiveness analysis is also provided.

Spin-induced multipartite steady-state entanglement of motional modes in hexagonal boron nitride membranes

In this paper, we focus on a scheme in which three high-quality-factor mechanical modes of a hexagonal boron nitride (hBN) membrane monolayer are coupled to a common optically addressable spin defect present in the membrane via magnetic field interaction. We show that this coupling induces an effective phonon-phonon interaction in the dispersive regime and under appropriate magnetic field and microwave modulation. We derive the Langevin-Heisenberg equations of motion for vibrational modes to analyze optimal parameter regimes for reaching a physically stable system. We also investigate the effect of coupling strength on purity and entanglement. Our results demonstrate that bipartite and genuinely tripartite steady-state entanglement between different vibrational modes of hBN may be achieved in a broad spectrum of experimental parameters. This study has the potential to enable scalability to be implemented for the generation of two-dimensional continuous-variable cluster states for universal quantum computation.

Magnetic field and nuclear spin influence on the DNA synthesis rate

The rate of a chemical reaction can be sensitive to the isotope composition of the reactants, which provides also for the sensitivity of such “spin-sensitive” reactions to the external magnetic field. Here we demonstrate the effect of the external magnetic field on the enzymatic DNA synthesis together with the effect of the spin-bearing magnesium ions (^{25}Mg). The rate of DNA synthesis monotonously decreased with the external magnetic field induction increasing in presence of zero-spin magnesium ions (^{24}Mg). On the contrary, in the presence of the spin-bearing magnesium ions, the dependence of the reaction rate on the magnetic field induction was non-monotonous and possess a distinct minimum at 80–100 mT. To describe the observed effect, we suggested a chemical scheme and biophysical mechanism considering a competition between Zeeman and Fermi interactions in the external magnetic field.

Magnetic field-induced asymmetric mechanical metamaterials

We propose a magnetic field-induced asymmetric mechanical metamaterial. The tunable metamaterial integrates hard-Magnetic Active Elastomers (hMAEs) into the microstructural design combining snap-through, bi-stability, and local resonant effects. The proposed metamaterial design comprises resonating units made out of hMAE, and these units are supported by highly deformable curved beams connected with an elastomeric matrix. Activated by a magnetic field, the resonating units attain an unstable regime with dramatic configuration and stiffness variation. These controlled transformations significantly affect the elastic wave propagation. We illustrate that the proposed magnetoactive metamaterial enables bandgap tunability over a broadband low-frequency range. Thus, the proposed design allows remote and reversible control of the metamaterial performance. Moreover, the hMAE-based systems can incorporate the polarity and chirality stemming from the interaction of external magnetic fields and hMAE phases, giving rise to the unusual behavior of the metamaterial, and potentially enabling elastic cloaking.