Effect Of External Magnetic Field Research Articles

Magnetic field assisted centrifugal acceleration thin-layer chromatography: An approach to investigate the magnetic field effects on separation parameters including retention factor difference, selectivity factor, and resolution

The effect of internal and external magnetic fields on the separation of antifungal drugs by centrifugal acceleration thin-layer chromatography was reported for the first time. External and internal magnetic fields were applied using neodymium magnets and CoFe2O4@SiO2 ferromagnetic nanoparticles. Separation of ketoconazole and clotrimazole was performed using a mobile phase consisting of n-hexane, ethyl acetate, ethanol, and ammonia (2.0:2.0:0.5:0.2, v/v). The influence of the magnetic field on the entire chromatographic system led to changes in the properties of the stationary and mobile phases and the analytes affecting the retention factor, shape, and width of the separated rings. The extent of this impact depended on the structure of the analyte and the type and intensity of the magnetic field. In the presence of the external magnetic field, there were more significant changes in the chromatographic parameters of the drugs, especially the width of the separated rings, and ketoconazole was more affected than clotrimazole. The changes are conceivably due to the effect of the magnetic field on the analyte distribution between the stationary and mobile phases, which is also caused by the possibility of the magnetic field affecting the viscosity, surface tension, and surface free energy between the stationary and mobile phases.

Analysis of the performance and microbial community of continuous dark fermentation combined with steady static magnetic field

The effect of external static magnetic field on hydrogen production and its mechanism were studied by continuous dark fermentation with no pretreatment excess sludge as inoculum. The results showed that under conditions of 37 ± 1 ℃, HRT 8h, OLR 15g/(L· d) and no control of influent pH, 78 mT external static magnetic field by adding magnets on both sides of the reactor could accelerate the enrichment of Ethanoligenens and improve the activity of reduced coenzyme I (96%), ferredoxin oxidoreductase (29%) and pyruvate: ferredoxin oxidoreductase (7%) so that the maximum hydrogen productivity could reach 1.657L H2/L, which was 5 times higher than that of non-magnetic group. Moreover, the n-caproic acid production could also increase due to the enrichment of carbon chain elongation microorganisms. The decline of hydrogen production was mainly due to hydrogenotrophic methanogenesis and acetic acid accumulation. This study was benefit to understand the interaction mechanism between magnetic field and microorganisms during the process of biological hydrogen production.

Influence of ferromagnetic interlayer exchange coupling on current-induced magnetization switching and Dzyaloshinskii-Moriya interaction in Co/Pt/Co multilayer system.

This paper investigates the relationship among interlayer exchange coupling (IEC), Dzyaloshinskii-Moriya interaction (DMI), and multilevel magnetization switching within a Co/Pt/Co heterostructure, where varying Pt thicknesses enable control over the coupling strength. Employing Brillouin Light Scattering to quantify the effective DMI, we explore its potential role in magnetization dynamics and multilevel magnetization switching. Experimental findings show four distinct resistance states under an external magnetic field and spin Hall effect related spin current. We explain this phenomenon based on the asymmetry between Pt/Co and Co/Pt interfaces and the interlayer coupling, which, in turn, influences the DMI and subsequently impacts the magnetization dynamics. Numerical simulations, including macrospin, 1D domain wall, and simple spin wave models, further support the experimental observations of multilevel switching and help uncover the underlying mechanisms. Our proposed explanation, supported by magnetic domain observation using polar-magnetooptical Kerr microscopy, offers insights into both the spatial distribution of magnetization and its dynamics for different IECs, thereby shedding light on its interplay with DMI, which may lead to potential applications in storage devices.

Accuracy improvement enzyme-linked immunosorbent assay using superparamagnetic/polyethylene glycol) nanoparticles for leishmaniasis diagnostic

Serodiagnosis methods have been used as platforms for diagnostic tests for many diseases. Due to magnetic nanoparticles' properties to quickly detach from an external magnetic field and particle size effects, these nanomaterials' functionalization allows the specific isolation of target analytes, enhancing accuracy parameters and reducing serodiagnosis time. Superparamagnetic iron oxide nanoparticles (MNPs) were synthesized and functionalized with polyethylene glycol (PEG) and then associated with the synthetic Leishmaniosis epitope. This nano-peptide antigen showed promising results. Regarding Tegumentary leishmaniasis diagnostic accuracy, the AUC was 0.8398 with sensibility 75% (95CI% 50.50 - 89.82) and specificity 87.50% (95CI% 71.93 - 95.03), and Visceral leishmaniasis accuracy study also present high performance, the AUC was 0.9258 with sensibility 87.50% (95CI% 63.98 - 97.78) and specificity 87.50% (95CI% 71.93 - 95.03). Our results demonstrate that the association of the antigen with MNPs accelerates and improves the diagnosis process. MNPs could be an important tool for enhancing serodiagnosis.

Irreversibility estimation in triply stratified bio-marangoni convection in powell-eyring nanofluid under the influence of external flow

Due to the growing importance of bioconvection phenomena in diverse industrial processes such as oil refining, biotechnology, and food processing, it is essential to examine several effects like a chemical reaction, stratification, Marangoni convection, etc in nanofluid suspensions in the context of transport of microorganisms. The outcome of such studies may provide significant insight into controlling and as well as manipulating the transport of energy, solute, and microorganisms for achieving the requisite target. The aim of our study is to investigate the thermo-solutal Marangoni convection of gyrotactic microorganisms suspended in Powell-Eyring nanofluid in a stratified medium. This analysis also takes into account the effects of external flow and transverse magnetic field. The impact of Arrhenius activation energy, thermal radiation, and binary chemical reactions on bioconvection flow is considered under stratified Marangoni convection. Under appropriate assumptions without violating the physics, the present problem is expressed in terms of nonlinear PDEs. Some capable similarity transformations are employed to convert the PDEs into ODEs and solved numerically by the Runge-Kutta Fehlberg method. The graphical illustrations depict the effects of relevant flow parameters on temperature, nanoparticle volume fraction, and density distributions of motile microorganisms. The study focuses on understanding the variations in significant engineering quantities resulting from changes in crucial effects and analyzing irreversibilities. It is noticed that Marangoni accelerates the mass transfer process while on the other hand delaying the heat transfer and microorganisms density gradient. The dominance of Powell-Eyring nanofluid on the heat and mass transport amplified in accompanying Marangoni convection. The results indicate that the Eyring-Powell fluid significantly reduces entropy generation and the Bejan number. Conversely, an increase in entropy generation is observed for the Marangoni ratio parameter. Hence, this work provides insight into interlinked flow in bioconvective systems, with potential diverse applications in microbiological processes.

Effect of dense plasma environment and external magnetic field on atomic structure and radiative properties of Ar XVII

Atomic structures and radiative properties of He like Ar XVII in the presence of dense plasma environments and external magnetic field have been presented within the framework of the relativistic theory. For this purpose, the relativistic configuration interaction method by incorporating the generalized b-potential and external magnetic field has been implemented. Plasma screening effect on 1s2 1S0 → 1s2p 3P1 transitions of Ar XVII ion in the presence of an external magnetic field has been investigated. We also studied the Zeeman splitted energies and predicted the excitation energies of Ar XVII ion for the magnetic sublevels 1s2p 3P0 (MJ = 0), 3P1 (MJ = 0, ±1), 3P2 (MJ = 0, ±1, ±2), 1P1 (MJ =0, ±1). Our calculated results are in excellent agreement with National Institute of Science and Technology (NIST) database and other theoretical available data.

The effect of intrinsic magnetic order on electrochemical water splitting

To reach a long term viable green hydrogen economy, rational design of active oxygen evolution reaction (OER) catalysts is critical. An important hurdle in this reaction originates from the fact that the reactants are singlet molecules, whereas the oxygen molecule has a triplet ground state with parallel spin alignment, implying that magnetic order in the catalyst is essential. Accordingly, multiple experimentalists reported a positive effect of external magnetic fields on OER activity of ferromagnetic catalysts. However, it remains a challenge to investigate the influence of the intrinsic magnetic order on catalytic activity. Here, we tuned the intrinsic magnetic order of epitaxial La0.67Sr0.33MnO3 thin film model catalysts from ferro- to paramagnetic by changing the temperature in situ during water electrolysis. Using this strategy, we show that ferromagnetic ordering below the Curie temperature enhances OER activity. Moreover, we show a slight current density enhancement upon application of an external magnetic field and find that the dependence of magnetic field direction correlates with the magnetic anisotropy in the catalyst film. Our work, thus, suggests that both the intrinsic magnetic order in La0.67Sr0.33MnO3 films and magnetic domain alignment increase their catalytic activity. We observe no long-range magnetic order at the catalytic surface, implying that the OER enhancement is connected to the magnetic order of the bulk catalyst. Combining the effects found with existing literature, we propose a unifying picture for the spin-polarized enhancement in magnetic oxide catalysts.

Fabrication and performance enhancement of TMR-Superconducting composite magnetic sensors for weak magnetic field detection

The tunneling magnetoresistance (TMR) effect, utilizing the CoFeB/MgO/CoFeB magnetic tunnel junction (MTJ) structure, has seen a surge in research interest owing to its pronounced sensitivity to magnetic fields. However, advancements in TMR technology have plateaued in recent times. In response, this study explores the integration of TMR with superconductivity to form a TMR-superconducting composite magnetic sensor, aiming to amplify the external magnetic field effect and improve sensor performance. Such sensors offer significant promise for applications in detecting feeble magnetic fields due to their compact dimensions, minimal energy consumption, and exceptional magnetic field resolution. Despite their potential, manufacturing challenges persist. This paper focuses on the meticulous fabrication of the TMR's critical thin film layer and its subsequent patterning. Moreover, we propose an innovative technique utilizing magnetron sputtering to deposit a niobium (Nb) layer atop the TMR structure, followed by intricate patterning to successfully construct a TMR-superconducting composite film. This novel approach importantly diminishes the interspace between TMR and superconducting layers compared to traditional bonding methods, thereby enhancing device performance. Experimental assessments of the device constructed superconducting loops, contrasted with traditional bonding process, demonstrate that sputtering-based sensor exhibit better magnetic field resolution. Consequently, TMR-superconducting composite sensors realized via the sputtering technique hold distinct advantages in weak magnetic field detection.

Effect of external magnetic field on electric current-induced fracture of notched thin metallic conductors: Part 2- High magnetic fields

In the companion report (Telpande et al., n.d.), we discussed the impact of a weak external magnetic field (up to 0.4 T) on the electric current-induced fracture of pre-notched thin metallic conductors, revealing a linear decrease in critical current density, jc, necessary for crack propagation. This study extends the investigation to explore the effects of stronger external magnetic fields (0.6–1 T) on the fracture of pre-notched, current-carrying metallic foils. The experimental analysis reveals a substantial, albeit linear, drop (up to 40 %) in jc under stronger magnetic fields. Interestingly, calculations of the dynamic stress intensity factor, KIE,t, which assesses the interplay between applied current density and external magnetic field, indicate crack growth under a strong magnetic field even when KIE,t is below the plane stress critical stress intensity factor, KIC. A remarkable phenomenon emerges: the application of electric current pulses combined with strong external magnetic fields induces observable surface undulations near the notch tip. A comprehensive 3D finite element model, integrating linear and nonlinear buckling analyses under multiphysics stimuli, attributes these undulations to localized buckling near the notch tip. This buckling-induced stress redistribution near the crack tip contributes to an overall reduction in fracture toughness due to mode mixity, leading to the fracture of the Al foil below KIC. This investigation, along with the companion report (Telpande et al., n.d.), significantly advances our understanding of the effects of magnetic fields on the fracture of current-carrying conductors.

Critical behavior of a mixed-spin Ising model on a square–octagon lattice

The magnetic behavior and phase diagrams of a mixed spin-5/2 and spin-3/2 Ising system on a two-dimensional square–octagon lattice were investigated using the mean-field approach based on the statistical Bogoliubov inequality. Two ground-state phase diagrams were plotted in two different planes. We also examined the effects of exchange interactions, crystal field, and external magnetic field on the magnetizations and phase diagrams of the system. First- and second-order phase transitions and isolated critical points were obtained for certain physical conditions. The influence of various physical system parameters on the blocking temperature was also clarified.

The effect of external magnetic field on the instability of THz plasma waves in nanoscale graphene field-effect transistors

Abstract The instability of plasma waves in the channel of field-effect transistors will cause the electromagnetic waves with THz frequency. Based on a self-consistent quantum hydrodynamic model, the instability of THz plasmas waves in the channel of graphene field-effect transistors has been investigated with external magnetic field and quantum effects. We analyzed the influence of weak magnetic fields, quantum effects, device size, and temperature on the instability of plasma waves under asymmetric boundary conditions numerically. The study results show that the magnetic fields, quantum effects, and the thickness of the dielectric layer between the gate and the channel can increase the radiation frequency. Additionally, we observed that increase in temperature leads to a decrease in both oscillation frequency and instability increment. The numerical results and accompanying images obtained from our simulations provide support for the above conclusions.

Effects of external light in the magnetic field-modulated photocatalytic reactions in a microfluidic chip reactor.

Photocatalytic reactions and their magnetic-field enhancement present significant potential for practical applications in green chemistry. This work presents the mutual enhancement of plasmonic photocatalytic reaction by externally applied magnetic field and plasmonic enhancement in a micro optofluidic chip reactor. The tiny gold (Au) nanoparticles of only a few atoms fixed on the surface of titanium dioxide (TiO2) nanoparticles lead to mutually boosted enhancement photocatalytic reactions under an external magnetic field and plasmonic effects. The dominant factor of adding green light to the photocatalytic reaction leads to the understanding that it is a plasmonic effect. The positive results of adding ethanol alcohol (EA) in the experiments further present that it is a hot electron dominant path photocatalytic reaction that is positively enhanced by both the external magnetic field and plasmonic effects. This work offers great potential for utilizing magnetic field enhancement in plasmonic photocatalytic reactions.

Effects of Josephson junction synapse on coupled Morris-Lecar neurons

Recently, various artificial synapses have been examined in neural networks for obtaining different dynamical characteristics of neurons. The Josephson junction can be used for constructing an artificial synapse that incorporates the external magnetic field effects. Using the Josephson junction for coupling the neurons involves the phase error between the junctions. This paper uses the Josephson junction and a linear resistor to connect two Morris-Lecar neuron models. The effects of Josephson junction parameters are investigated on the dynamical properties of neurons. The obtained bifurcation and Lyapunov exponent diagrams represent that the Josephson junction synapse significantly affects the neurons’ dynamics. Rich dynamics are observed by varying the junction parameters. Moreover, the multistability properties are reported. Finally, the synchronization of coupled neurons is studied under different junction's parameters.

Effects of external magnetic fields on the confined states and optical properties of conical quantum dot nanowire

In this paper, we have investigated theoretically the effect of the external magnetic fields on the electronic structuctures and optical properties of a nanosystem consisting of a conical InAs quantum dot embedded in an infinite GaAs nanowire. To this end the Schrodinger equation have been solved numerically utilizing the effective mass approximation to calculate the confined energy states and binding energies of the system. The findings demonstrate that under the effect of the magnetic fields, the energies of confined states in the Quantum Dot of +|m| and −|m| angular momentum have been separated and increased toward the energy continuum of the nanowire. It has been shown that the lower limit of energy continuum of ±m states are split which results in different binding energy for states of +|m| and −|m| angular momentum. Finally, the oscillator strength for intersubband transitions between the system's confined energy states has been explored in order to discuss the optical properties of the described system.

Terahertz field generation from laser interaction with spherical nano-particles: effect of external magnetic field

Terahertz field generation from laser interaction with spherical nano-particles: effect of external magnetic field

A Josephson junction-coupled neuron with double capacitive membranes

The channel currents have distinct magnetic field effect and any changes of the electromagnetic field or electirc stimulus will change the membrane potential effectively. A feasible neuron model considers the distinct physical characteristic is more suitable to mimic the neural activities accompanying with shift in energy level. A Josephson junction (JJ) is connected to a neural circuit for estimating the effect of external magnetic field and two capacitors are connected via a linear resistor for mimicing the capacitive field beside two sides of the cell membrane. Its equivalent Hamilton energy is calculated to show the relation between firing mode and energy level. Noisy disturbance is imposed to predict the occurrence of coherence resonance, and the biophysical neuron is excited to present higher energy level. This new neuron model can address the field effect and the biophysical property of cell membrane considered as combination of capacitive fields in double capacitors. It can mimic the physical property of outer and inner membranes, and energy exchange across the double membranes explains the energy mechanism in neural activities. Time-varying energy diveristy between capacitive field is crucial for supporting continuous firing activities. The JJ channel discerns slight changes in external magnetic field and regularity is stabilized under coherence resonance in presence of noisy excitation on the membrane or ion channels.

External and Crystal Magnetic Field Effects on the Compensation Phenomena of Mixed-Spin (5/2, 7/2) Hexagonal Ising Nanowire

External and Crystal Magnetic Field Effects on the Compensation Phenomena of Mixed-Spin (5/2, 7/2) Hexagonal Ising Nanowire

Effect of external magnetic fields on practical quantum random number generator

Quantum random number generator (QRNG) based on the inherent randomness of fundamental quantum processes can provide provable true random numbers which play an important role in many fields. However, the security of practical QRNGs is linked to the performance of realistic devices. In particular, devices based on the Faraday effect in a QRNG system may be affected by external magnetic fields, which will inevitably open a loophole that an eavesdropper can exploit to steal the information of generated random numbers. In this work, the effects of external magnetic fields on the security of practical QRNGs are analyzed. Taking the quantum phase fluctuation based QRNG with unbalanced Michelson interferometer as an example, we experimentally demonstrate the rotation angle of the Faraday rotation mirror (FRM) is influenced by external magnetic fields. Then, we develop a theoretical model between the rotation angle deviation of FRM and conditional min-entropy. Simulation results show that the imperfect FRM leads to a reduction in the variance of measured signal and extractable randomness. Furthermore, the impacts of practical sampling device on the extractable randomness are analyzed in the presence of imperfect FRM, which indicates suitable parameters of the sampling device can improve the security of practical QRNGs. Potential countermeasures are also proposed. Our work reveals that external magnetic fields should be carefully considered in the application of practical QRNGs.

Monte Carlo study of magnetocaloric effect and magnetic properties of the nano- borophene bilayer with RKKY exchange interactions of a mixed spin 2 and 3/2

In this study, we have studied the magnetic properties and magnetocaloric effect of the nano-borophene bilayer with RKKY (Ruderman-Kittel-Kasuya-Yosida) exchange interactions of mixed spin 2 and 3/2 using Monte Carlo calculations. In the first part of this investigation, the ground state phase diagrams for zero temperature are reported and discussed. We also determined the critical temperature for varying the number of non-magnetic layers (NML) and the interacting couplings Jss. In the second part, we investigated the influence of the parameter NML, the exchange couplings Jss and Jσσ, and the crystal field on the total magnetizations and the magnetic hysteresis loop. The specific heat and magnetic entropy changes versus of the temperature under the effect of different external magnetic fields and the parameter Jss. Finally, we analyzed the relative cooling power (RCP) for distinct external magnetic field and Jss.

Study on the propagation properties of terahertz waves in spacecraft dusty plasma sheath

Terahertz (THz) wave transmission in non-uniform dielectric layer containing dusty plasmas and aluminum (Al) is investigated by using the Wentzel–Kramer–Brillouin method. The application of magnetic field and increase in electromagnetic waves frequency are up-and-coming solutions for the “blackout” issue. Therefore, this work considers the effect of external magnetic field and electron density distribution. The electron density distributions are assumed to be double Gaussian profile, uniform distribution, Epstein distribution, and both right- and left-hand circularly polarized waves are analyzed. Then the effects of physical parameters and THz frequency on the transmission properties are analyzed. Results show that the presence of Al can shield electromagnetic waves, but we can still control THz waves in lower frequency band to achieve communication. By adjusting THz waves frequency and plasma parameters, waves can pass through the Al plasma sheath effectively under certain circumstances. It is expected to mitigate the blackout issue of hypersonic spacecraft.