Application Of Magnetic Field Research Articles

Advances in sample environments for neutron scattering for colloid and interface science

This review describes recent advances in sample environments across the full complement of applicable neutron scattering techniques to colloid and interface science. Temperature, pressure, flow, tensile testing, ultrasound, chemical reactions, IR/visible/UV light, confinement, humidity and electric and magnetic field application, as well as tandem X-ray methods, are all addressed. Consideration for material choices in sample environments and data acquisition methods are also covered as well as discussion of current and potential future use of machine learning and artificial intelligence.

Giant magnetoimpedance effect and spin accumulation in conjugated polymeric networks with inhomogeneity

The magnetoimpedance effect allows us to estimate the extent of spin dependent scattering in disordered solids. The change in impedance with respect to applied magnetic field manifests through local change in permeability on the surface and it amplifies at defect sites. The local electrical inhomogeneities are expected to aid this effect through spin dependent scattering. The organic conjugated electrical networks provide scope for producing such inhomogeneities formed by path defects and protonic charge accumulation leading to spin dependent scattering. This hypothesis is investigated in the present work taking polyaniline as a prototype network. The electrical inhomogeneities in the network were controlled by selective oxidation and aging in polyaniline. The Giant Magnetoimpedance (GMI) was observed in the electrically inhomogeneous network with the change in electrical impedance of the order of 50%–60% for lower frequencies with prominent capacitive coupling and a change of the order of 200% at higher frequencies with prominent inductive coupling with the application of magnetic field. However, no spin accumulation was observed in the insulating networks formed by a modified oxidative process. This study is expected to serve as a tool to develop frequency selective spin accumulation based magnetic field sensors and oscillator networks.

Exploring induced microstructural changes in magnetically modified crude oils through nonlinear rheology and magnetometry

Adsorptive phenomena involving dispersed iron oxide superparamagnetic nanoparticles and asphaltenes in crude oil have been profiled as promising technological alternatives, particularly since these interactions can induce significant structural changes within the oil matrices, effectively inhibiting the formation of complex long-range viscoelastic structures. Furthermore, the effect of adsorbed asphaltenes on magnetic dipolar interactions among particles has been proven, showing the formation of multiple asphaltene layers that stimulate a steric repulsive barrier. Despite the discussed hindering phenomena, this research demonstrated the effectiveness of the sequence of physical processes framework to provide intra-cycle structure-rheological interpretations in large amplitude oscillatory shear of a ferrofluid-modified heavy oil, upon the application of an external magnetic field. The analysis proved that disordered nanoparticle/asphaltene aggregates are highly extended and naturally formed in the absence of magnetic forces. In contrast, in the presence of a perpendicular field applied by a controlled rate magneto-rheometer, the formation of interacting structural aggregates of several hundred nanometers was observed, analogous to magnetorheological fluids. These results were validated by adjusting a phenomenological model that effectively represented the intricate processes involved in the formation and reorientation of aggregates, based on the experimental data acquired from zero-field-cooled and field-cooled magnetization curves. This revealed a distinct blocking temperature distribution at around 274 K, which was linked to Brownian relaxation phenomena exhibited by nanoparticle aggregates. In this regard, this research provided a precise extended description of the effect of magnetic fields on the microstructural organization of complex fluids using nonlinear rheology and magnetometry.

A new capacitive inductive system design for LASER-induced kilotesla magnetic field generation

This research focuses on exploring the nanosecond laser-driven coil systems capable of generating kT magnetic fields and the diverse applications of this system. Through investigating the effects of laser parameters and coil structures, the aim of this study is to unveil the physics of these generated intense magnetic fields. The outcomes gained from this research give an important and fundamental understanding on high magnetic field production, informing the development in laser-driven systems. The implications of this study extend to plasma physics, astrophysics simulations and fusion research. Furthermore, the study explains the advantages and applications of these intense magnetic fields and includes measurements of laser pulse powers according to coil materials.

Magnetic-Field-Induced Spin Regulation in Electrocatalytic Reactions.

The utilization of a magnetic field to manipulate spin states has emerged as a novel approach to enhance efficiency in electrocatalytic reactions, distinguishing from traditional strategies that focus on tuning activation energy barriers. Currently, this approach is specifically tailored to reactions where spin states change during the catalytic process, such as the oxidation of singlet H2O to triplet O2. In the magnetically enhanced oxygen evolution reaction (OER) procedure, the parallel spin alignment on the ferromagnetic catalyst was induced by the external magnetic field, facilitating the triplet O-O bonding, which is the rate limiting step in OER. This review centers on recent advancements in harnessing external magnetic fields to enhance OER performance, delving into mechanistic approaches for this magnetic promotion. Additionally, we provide a summary of magnetic field application in other electrocatalytic reactions, including oxygen reduction, methanol oxidation, and CO2 reduction.

Magnetic Field Induction ZnFe2O4@Carbon for Construction of a PVDF‐HFP‐Based 3D Dielectric Network

AbstractFunctional fillers in the polymerization system cannot be arranged in an orderly manner when exposed to natural conditions. The application of magnetic fields in the material preparation process has been shown to greatly enhance the distribution of functional fillers, leading to the organized alignment of functional fillers and the production of polymer matrix composites with remarkable characteristics. In this experiment, rod‐like ZnFe2O4 was synthesized by reverse microemulsion method, and amorphous carbon was coated on the surface of ZnFe2O4 by freeze‐drying method to obtain ZnFe2O4@Carbon core‐shell particles. The composite films were prepared by dispersing ZnFe2O4 with different volume contents into P(VDF‐HFP) matrix. The external parallel magnetic field was used to manipulate the ZnFe2O4@C/P(VDF‐HFP) composite film during the hot‐pressing process, resulting in an oriented ZnFe2O4@C/P(VDF‐HFP) composite film. The experiment revealed that when ZnFe2O4@C is aligned with the film orientation, the dielectric constant of the composite film is 50(50 Hz), which is 130 % higher than that of the unoriented composite film and 290 % higher than that of pure P(VDF‐HFP). When the filling amount is 40 Vol.%, the energy storage density of ZnFe2O4@C/P(VDF‐HFP) composite film is 1.18 times higher than that of unoriented composite material and 1.32 times higher than that of pure P(VDF‐HFP).

Enhanced adsorption of polystyrene nanoplastics by cetyltrimethylammonium bromide surface-modified magnetic rice straw biochar: Efficient performance and adsorption mechanisms

Nanoplastics, characterized by their small size, high diffusion, and stability, have attracted wide attention worldwide as a new potentially threatening pollutant. In this study, magnetic rice straw biochar modified with cetyltrimethylammonium bromide (CTAB) was prepared and utilized for the adsorption removal of polystyrene nanoparticles (PSNPs, <100 nm). The characteristics and adsorption performance of CTAB modified magnetic biochar (MBC-CTAB) were systematically investigated using characterization techniques and batch adsorption experiments. The grafting of alkyl chains onto the biochar surface through surfactant modification improved the surface activity and adsorption capacity of the magnetic biochar towards nanoplastics. Moreover, the application of an external magnetic field facilitated the rapid separation and recovery of MBC-CTAB. MBC-CTAB exhibited a removal efficiency of 99.56 % for 20 mg/L PSNPs, with a maximal adsorption capacity of 54.07 mg/g at 298 K. The presence of anions such as HPO42− and CO32− as well as dissolved organic compounds like humic acid creates significant competition between PSNPs, thereby inhibiting the adsorption capacity of MBC-CTAB towards PSNPs. The mechanism of MBC-CTAB for nanoplastics adsorption can be attributed to electrostatic interaction, hydrophobic interactions, pore filling, and surface complexation. This study demonstrates the feasibility of using surfactant-modified biochar for the adsorption of nanoplastics, providing a promising option for the development of new pollutant treatment technologies and the mitigation of the adverse impacts of nanoplastics on the environment and ecosystems.

Tunable anomalous Hall effect in Pt/ferrimagnetic insulator bilayer

Ferrimagnetic insulators (FMIs) are regarded as promising candidates for magnonic devices. Nevertheless, unraveling the origin of anomalous Hall effect (AHE) and tuning AHE in heavy metal (HM)/FMI prove challenging as charges exclusively traverse within the HM. Here, we investigate AHE in a Pt/Gd3Fe5O12 (GdIG) bilayer at various temperatures and observe a signal inversion at 180 K. By varying the thickness of GdIG and Pt, we note that AHE signal inversion occurs in all instances except when the Pt thickness is below 3 nm. Moreover, the monotonic variation in the temperature dependence of the coercive field (Hc) indicates that the inversion of the AHE signal is not correlated with the compensation temperature (Tc). Instead, it is attributed to the competition between spin Hall magnetoresistance (SMR) and the magnetic proximity effect (MPE). Furthermore, the precise control over the AHE inversion has achieved through the application of extra in-plane magnetic fields (Hx). Our study clarifies the origins of the AHE in Pt/FMI bilayers, where the interaction between the SMR and MPE governs the direction and magnitude of the AHE. Furthermore, we showcase the ability to control the inversion of the AHE signal by manipulating the extra Hx.

Intertwined crystal structure, magnetic, and charge transport properties in mixed valent A-site ordered manganite NdBaMn2O6

In the present work, we report a correlation between crystal structure, magnetic, and electrical properties in an exotic magnetic compound, NdBaMn2O6 having ∼92% ordering between Nd and Ba, investigated using temperature-dependent synchrotron x-ray diffraction (XRD), dc magnetization and transport measurements. Temperature-dependent XRD data reveals that the compound undergoes various complex crystallographic phase transitions from high-temperature (T > 320 K) P4/mmm phase to intermediate (320 K – 280 K) Cmmm phase to a mixed (Cmmm and P21am) phase (280 K – 220 K) and to low-temperature P21am phase (T < 220 K). It is found that these crystallographic phase compositions play a crucial role in controlling its magnetic and transport properties. Temperature-dependent dc magnetization data show a sharp drop at the onset of mixed phase (Cmmm + P21am) at 280 K followed by a broad hump at ∼ 220 K where mixed phase to P21am transition occurs, thus indicating a correlation between the structural and magnetic properties. The dc magnetization in the mixed phase region is calculated by considering a superposition of the magnetic moments of Cmmm and P21am phases weighted by the fraction of each phase, which exactly follows the experimental magnetization data. Temperature variation of resistivity data shows a jump at ∼260 K, a temperature corresponding to 50–50% phase composition of Cmmm and P21am phases. The compound shows insulating behavior over a whole temperature range as confirmed from the resistivity data. Further, application of magnetic field causes a shift of magnetic and transport transition temperatures which may be due to the magnetic field induced structural transition in the system.

Magnetic field and a bio-based solvent as greener alternatives in Phaffia rhodozyma cultivation: insights into astaxanthin and antioxidant activity thermal degradation

This study aimed to evaluate magnetic fields (MF) and a bio-based solvent as greener alternatives for processing natural astaxanthin from Phaffia rhodozyma biomass. To improve carotenoid production, MF was evaluated using a central composite design (CCD), which demonstrated effectiveness by increasing astaxanthin production by 24.8% and productivity by 78.9% by comparison with the control in validated models. In the context of solid-liquid extraction, an environmental assessment of astaxanthin recovery identified ethanol (EtOH) as a promising and sustainable alternative, with an 89% recovery yield during processing. Furthermore, the study inspired an assessment of the stability of carotenogenic extracts at various temperatures throughout time, providing useful information about antioxidant activity and color parameters during storage. This study is one of the first to incorporate insights into the use of MF application and a bio-based solvent as greener alternatives for processing natural astaxanthin from P. rhodozyma biomass.

On the Electrodeposition of Zinc in Low Magnetic Fields

Abstract While aqueous zinc-based batteries have garnered much research on account of their improved safety, lower cost, and easier fabrication over lithium-ion batteries, they remain held back by dendrite growth on the anode. While many different solutions have been proposed, these solutions often greatly complicate the synthesis or materials in the battery. The application of a magnetic field across the battery has been shown to inhibit dendrite formation without the need for any materials or interface engineering. Herein, we provide a study on the effects of low magnetic fields on the electrodeposition and cycling of zinc in various aqueous systems. We demonstrate that although stronger fields have more immediate impacts on the morphology of zinc deposits, low magnetic fields are still suitable for inhibiting dendrite growth over long periods of cycling. Magnetic field strengths as low as 29 mT were shown to decrease charge transfer resistance of zinc ion deposition by up to 54% and to stabilize the cycling of Zn/Zn symmetric cells. Furthermore, the versatility of magnetic field application was demonstrated by affecting the morphology of zinc deposits on both copper and single-walled carbon nanotubes, which are both compatible with anode-free configurations of aqueous zinc-ion batteries.

Measurement of Rubidium Vapor Density Based on Spin‐Exchange Rate

AbstractAn efficient method is proposed for quantifying rubidium vapor density by analyzing the spin‐exchange rate between alkali metals. This method effectively addresses two primary challenges in measuring alkali vapor density. First, it overcomes the limitation of absorption spectroscopy to measure vapor density under optically thick conditions, typically restricted to temperature higher than 420K, equivalent to alkali vapor density exceeding . Second, it mitigates the risk of disrupting shielding functionality due to the application of a strong magnetic field, often in the range of several tens of Gauss or higher, when employing the Faraday rotation for vapor‐density measurement. The spin‐exchange rate between atoms, inherently related to the vapor density, is evident in the electron‐paramagnetic‐resonance spectrum of spin‐polarized , thereby providing a possibility for measuring alkali vapor density. To eliminate overlap between two Lorentzian curves resulting from two decomposed components of an oscillating field, a small rotating magnetic field with identical amplitude and frequency but a 90‐degree phase shift along both the x and y axes is applied. This method is successfully employed to measure vapor density in the temperature range of 373–433 K, with the measured outcomes closely matching the saturation vapor curve.

Magnetic field application in bone tissue regeneration: issue current status and prospects for method development

Relevance. Magnets have long been used to treat various diseases, especially in inflammatory processes. According to existing historical data, magnetotherapy was already used in ancient times by the Chinese, Egyptians and Greeks. Different magnetic field strengths affect cells in different ways, with medium-strength magnetic fields being the most widely used. The review presents a brief history and current state of the issue of using a magnetic field in bone tissue regeneration. Modern knowledge about the mechanisms of physiological and reparative regeneration, restoration of bone tissue is clarified, and modern areas of bone tissue engineering are considered, taking into account the characteristics of microcirculation and the effect of a magnetic field on the physiology of bone tissue and reparative regeneration. One of the key findings of the review is that the magnetic field improves bone tissue repair by influencing the metabolic behavior of cells. Studies show that magnetotherapy promotes the activation of cellular processes, accelerates the formation of new bone tissue and improves its quality. It is also noted that the magnetic field has a positive effect on microcirculation, improving the blood supply to tissues and facilitating a better supply of nutrients to the site of injury. This contributes to faster wound healing and early rehabilitation of patients. Conclusion. Magnetotherapy is one of the effective physical and rehabilitation methods of treatment that will become increasingly important in modern medicine. However, further research is needed to better understand the mechanisms of action of a magnetic field on bone tissue and to determine the optimal parameters for its application.

Nonreciprocal transport in the superconducting state of the chiral crystal NbGe2

Due to the lack of inversion, mirror or other roto-inversion symmetries, chiral crystals possess a well-defined handedness which, when combined with time-reversal symmetry breaking from the application of magnetic fields, can give rise to directional dichroism of the electrical transport phenomena via the magnetochiral anisotropy. In this study, we investigate the nonreciprocal magneto-transport in microdevices of NbGe2, a superconductor with structural chirality. A giant nonreciprocal signal from vortex motions is observed during the superconducting transition, with the ratio of nonreciprocal resistance to the normal resistance γ reaching 6×105 T−1⋅A−1. Interestingly, the intensity can be adjusted and even sign-reversed by varying the current, the temperature, and the crystalline orientation. Our findings illustrate intricate vortex dynamics and offer ways of manipulation on the rectification effect in superconductors with structural chirality.

Magnetic colloidal nanoformulations to remotely trigger mechanotransduction for osteogenic differentiation

Nowadays, diseases associated with an ageing population, such as osteoporosis, require the development of new biomedical approaches to bone regeneration. In this regard, mechanotransduction has emerged as a discipline within the field of bone tissue engineering. Herein, we have tested the efficacy of superparamagnetic iron oxide nanoparticles (SPIONs), obtained by the thermal decomposition method, with an average size of 13 nm, when exposed to the application of an external magnetic field for mechanotransduction in human bone marrow-derived mesenchymal stem cells (hBM-MSCs). The SPIONs were functionalized with an Arg-Gly-Asp (RGD) peptide as ligand to target integrin receptors on cell membrane and used in colloidal state. Then, a comprehensive and comparative bioanalytical characterization of non-targeted versus targeted SPIONs was performed in terms of biocompatibility, cell uptake pathways and mechanotransduction effect, demonstrating the osteogenic differentiation of hBM-MSCs. A key conclusion derived from this research is that when the magnetic stimulus is applied in the first 30 min of the in vitro assay, i.e., when the nanoparticles come into contact with the cell membrane surface to initiate endocytic pathways, a successful mechanotransduction effect is observed. Thus, under the application of a magnetic field, there was a significant increase in runt-related transcription factor 2 (Runx2) and alkaline phosphatase (ALP) gene expression as well as ALP activity, when cells were exposed to RGD-functionalized SPIONs, demonstrating osteogenic differentiation. These findings open new expectations for the use of remotely activated mechanotransduction using targeted magnetic colloidal nanoformulations for osteogenic differentiation by drug-free cell therapy using minimally invasive techniques in cases of bone loss.

Direct observation of magnetic domain walls in glass-coated submicronic amorphous wires

Results on the magnetic domain walls in rapidly solidified magnetostrictive and non-magnetostrictive amorphous submicronic wires are reported. Utilizing Lorentz transmission electron microscopy (LTEM) for the first time in this context, we have visualized and analyzed the domain walls in such ultra-thin amorphous wires. All the investigated samples display vortex magnetic domain walls, regardless of wire composition or diameter. In non-magnetostrictive wires, the domain walls maintain their structure and symmetry under varying magnetic field conditions. In contrast, magnetostrictive wires show an elongation of their domain walls upon magnetic field application, a response linked to the magnetoelastic coupling between magnetostriction and internal stresses induced during wire preparation. This study advances the understanding of magnetization reversal processes in amorphous submicronic wires. The insights gained are crucial for future developments in miniaturized magnetic devices.

Magnetic nanoparticle loading and application of weak magnetic field to reconstruct the cake layer of coagulation-ultrafiltration process to achieve efficient antifouling: Performance and mechanism analysis

Abandoning the costly development of new membrane materials and instead directly remodeling the naturally occurring cake layer constitutes a dynamic, low-cost, long-lasting, and proactive strategy to "fight fouling with fouling". Several optimization strategies, including coagulation/modified magnetic seed loading and applying a weak magnetic force (0.01T) at the ultrafiltration end, improved the anti-fouling, retention, and sieving performances of conventional ultrafiltration process during the treatment of source water having complex natural organic matter (NOMs) and small molecule micropollutants. Two modified magnetic seeds we prepared were composite nano-seed particles (Fe3O4@SiO2-NH2 (FS) and Fe3O4@SiO2@PAMAM-NH2 (FSP)). Aim of the study was to regulate the formation of cake layer via comprehensive testing of the antifouling properties of optimized processes and related mechanistic studies. It was found to be essential to enhance the interception of xanthate and tryptophan proteins in the cake layer for improving the anti-fouling performance based on the correlation and redundancy analyses, while the use of modified magnetic seeds and magnetic field showed a significant positive impact on water production. Blockage modeling demonstrated the ability to form a mature cake layer during the initial filtration stage swiftly. This mitigated the risk of irreversible fouling caused by pore blockage during the early stage of coagulation-ultrafiltration. Morphologically, the reconstructed cake layer exhibited elevated surface porosity, an internal cavity channel structure, and enhanced roughness that can promote increased water flux and retention of water impurities. These optimized the maturity of the cake layer in both time and space. Density Functional Theory (DFT), Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, and Modified Extended Derjaguin-Landau-Verwey-Overbeek (MDLVO) calculations indicated aggregation behavior of matter on the cake layer to be enhanced effectively due to magnetic seed loading. This is mainly due to the strengthening of polar interactions, including hydrogen bonding, π-π* conjugation, etc., which can happen between the cake layer loaded with FSP and the organic matter. Under the influence of a magnetic field, magnetic force energy (VMF) significantly impacts the system by eliminating energy barriers. This research will provide innovative strategies for effectively purifying intricate source water through ultrafiltration while controlling membrane fouling.

Applied Magnetic Field Increases Magnetic Anisotropy in HDDR-Processed Nd-Fe-B Alloy

We investigate the effect of an applied magnetic field on the entire HDDR process using a customized reactor vessel and a warm-bore superconducting magnet. We analyzed the resulting properties produced at both a 0 applied field and a 2 Tesla applied field. We show that the application of a magnetic field throughout the HDDR process results in powders that exhibit a greater level of anisotropy compared to their ambient field counterparts.

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.

Empirical study of magnetohydrodynamic effect on fluid flow in clayey porous media

Enhancing oil recovery from clayey reservoirs is a significant challenge in petroleum industry due to complex interactions between fluids and rock surfaces, particularly clay swelling. This study presents the first empirical analysis of magnetic fields' impact on fluid flow in clayey porous media. Our core findings indicate that magnetic treatment of water increases oil recovery by an average of 15–30% in clayey media, with limited effectiveness in pure quartz media. Detailed experiments unraveled that improved recovery factor by magnetic treatment stem from both mitigated swelling and altered magnetic properties at clay surface; introducing 30% clay to porous medium decreased the recovery by 32% compared to pure quartz sand. Heating the clay to around 1000 °C to reduce its swelling property improved the recovery by only 16%, suggesting magnetic treatment is not solely attributed to clay swelling mitigation. Treating ferromagnetic films at clay surface with HCl to produce non-magnetic FeCl3 resulted in a high recovery factor, similar to the clay-free medium. Moreover, it was determined that a magnetic field intensity of 43760–51740 A/m is optimal for fluid displacement in clayey media. Notably, the intensity of 47760 A/m increased recovery to 84.5% in a 30% clay medium, compared to 49.7% without treatment. Interestingly, it was observed that the maximum flow rate was associated with zero potential difference across the medium, providing a faster method to determine the optimum magnetic field intensity. Lastly, the concept of ‘Magnetic memory’ was investigated, referring to the persistence of magnetic field's influence after its removal. Our findings indicated that pressure build-up time stability lasted 10 days post-treatment, after which water behavior reverts, and clay swelling resumes. This insight into the temporal dynamics of magnetic field application provides a deeper understanding of its long-term impacts on fluid flow in clayey reservoirs.