Application Of Magnetic Field Research Articles

Enhanced bioleaching of spent Li-ion batteries using A. ferrooxidans by application of external magnetic field

Recycling spent batteries is increasingly important for the sustainable use of Li-ion batteries (LIBs) and for countering the supply uncertainty of critical raw minerals (Li, Co, and Ni). Bioleaching, which uses microorganisms to extract valuable metals, is both economical and environmentally safe compared to other recycling methods, but its practical application is impaired by slow kinetics. Accelerating the process is a key for bioleaching spent LIBs on an industrial scale. Acidithiobacillus ferrooxidans (A. ferrooxidans), which thrives in extremely low pH conditions, has long been explored for bioleaching of spent LIBs. Metabolism of A. ferrooxidans involves the oxidation of magnetic Fe2+ and produces intracellular magnetic nanoparticles. The possibility of accelerating the leaching kinetics of A. ferrooxidans by the application of an external magnetic field is explored in this work. A weak static magnetic field is applied during the bioleaching of spent LIBs to recover Li, Ni, and Co using A. ferrooxidans. It is determined that 3 mT is the optimal field strength which allows the leaching efficiency of Li to reach 100% after only 2 days of leaching at a pulp density of 3 w/v % while without the external magnetic field, the leaching efficiency is limited to 57% even after 4 days. The leaching efficiency of Ni and Co also increases by nearly three-fold to >80% after 4 days of leaching. The proposed magnetic field-assisted bioleaching of spent LIBs using A. ferrooxidans substantially improves the leaching kinetics and thus the cost-effectiveness of the bioleaching process with minimal environmental impact, hence enabling environment-friendly recycling of raw materials that are increasingly becoming scarce. The positive effect of an external magnetic field on the metabolism of A. ferrooxidans demonstrated in this work provide a new set of tools to engineer the bioleaching process and the possibility for genetic modification of acidophile bacteria, especially targeted for magnetic enhancement.

Settlement stability, electrical properties, and magnetoelectric properties of Mn0.5Zn0.5Fe2O4-PbZr0.5Ti0.5O3 multiferroic fluids modulating by particle sizes

Mn0.5Zn0.5Fe2O4-PbZr0.5Ti0.5O3 (MZFO-PZT) multiferroic fluids with different MZFO particle sizes were prepared, and magnetoelectric coupling effects were observed to be enhanced at room temperature. The X-ray diffraction analysis (XRD) indicates that the MZFO and PZT particles are in the pure phases. Scanning electron microscopy (SEM) images illustrate a decrease in MZFO particle size with increased ball milling time. As the MZFO particle sizes decrease, the settlement stability of multiferroic fluids becomes worse. The dielectric constant displays a nonlinear variation, exhibiting a maximum value of 4.52 at 140 Hz when the MZFO particle size is 0.55 μm. The residual polarization strength decreases and increases as particle size decreases, while the saturation polarization strength decreases gradually. The application of magnetic field results in a notable enhancement of the dielectric characteristics and ferroelectric properties, which indicates the presence of magnetodielectric and magnetoelectric coupling effects. The magnetoelectric coupling coefficient (αME) is 15.14 V/(cm·Oe) when the MZFO particle size is 0.61 μm. By modifying the strength of the applied magnetic field, the αME attains a maximum value of 114.43 V/(cm·Oe). This approach offers an effective strategy for optimizing the magnetoelectric coupling effect of multiferroic materials. Therefore, it is expected to be used in new magnetoelectric devices such as magnetoelectric random memories and magnetic field sensors.

Direct measurement of magnetocaloric effect (MCE) in frustrated Gd-based molecular complexes

AbstractGeneration of low temperatures below 1 K has been required for applications and fundamental research, given this, development of new materials utilized for demagnetization cooling has extensively been performed in recent years. Here, we studied two polynuclear Gd3+-based molecular compounds of Gd0.33[Gd4(OH)4(OAc)3][Rh4Zn4(L-cys)12]·32H2O (1Gd) and Gd0.33[Gd4(OH)4(OAc)3][Ir4Zn4(L-cys)12]·28H2O (2Gd) (L-cys = L-cysteinate) which show paramagnetic even at low temperatures due to their frustrated arrangement of Gd3+ ions. We discuss the magnitude of the magnetocaloric effect (MCE) in them inferred from the isothermal magnetic entropy change ($${\Delta S}_{\text{M}}$$ Δ S M ) from isothermal magnetization data. The − $$\Delta S_{{\text{M}}}^{{{\text{max}}}}$$ Δ S M max of 1Gd and 2Gd are 15.15 J kg−1 K−1 and 17.49 J kg−1 K−1 occur at 2.0 K under an applied field from 0 to 7 T, respectively. We also discussed the results of heat capacity measurement under magnetic fields to confirm the validity of the entropy change for 1Gd. Furthermore, with an aim of detecting their MCE directly, we have developed a new non-magnetic and metal-free magnetocaloric measurement cell. The adiabatic temperature change ($$\Delta T_{{{\text{ad}}}}$$ Δ T ad ) occurs in a small amount of sample on an order of 102-microgram with the application and removal of various magnitude magnetic fields starting from several initial temperatures were detected directly, to evaluate the potential of them to be a refrigerant for an adiabatic demagnetization refrigerator. The instrumental design for direct measurements of MCE is described along with the construction details.

W and Cu double cationic vacancies on S-scheme Bi2WO6/CuS heterojunction induced spin polarization and facilitated magnetic enhancement of photocatalytic activity toward levofloxacin degradation

In this research, the Bi2WO6/CuS heterojunctions (Vw-BWO/Cu1-xS) with Cu vacancies and W vacancies were fabricated via hydrothermal and post-etching methods towards levofloxacin (LEV) degradation. Multiple characterizations and tests verified the presence of W and Cu vacancies, and the Vw-BWO/Cu1-xS 10:1 heterojunction exhibited favorable optical properties. Density function theory (DFT) calculations revealed that W, Cu cation vacancies induced electron spin polarization on the Vw-BWO/Cu1-xS, facilitating carrier separation, and allowing more holes to be participated in photocatalytic reaction. Moreover, the presence of W, Cu vacancies could increase active sites, facilitating LEV absorption and activation. The Vw-BWO/Cu1-xS 10:1 composite achieved the highest LEV removal of 90.61 % within 60 min of light exposure, which was 1.24 times of the BWO. Notably, application of an external magnetic field (20 mT) to the Vw-BWO/Cu1-xS 10:1 could enhance photocatalytic degradation of LEV, which was 1.46 times of that without external magnetic field. Additionally, possible degradation routes of LEV and ecotoxicity of degradation intermediate products were determined. This study opens up a feasible approach for introduction of cationic vacancies and spin polarization on heterojunctions to improve photocatalytic activity.

Theoretical analysis of InAs based Bi-tunable narrow band terahertz perfect absorber for thermal sensing application

In this paper, a bi-tunable metamaterial absorber comprising a subwavelength resonator of semiconducting material InAs and a metallic plane adhered to a dielectric layer has been proposed in the terahertz regime. Absorption of about 99.8 % is achieved at 4.446 THz with the application of magnetic field B = 0.4 T and a high tunability rate of 0.4 THz/T in the central resonance frequency due to the presence of a magnetostatically tunable H-shaped InAs resonator and polyimide dielectric layer. The same structure supports dual control over the resonance by replacing polyimide dielectric layer with InSb, as InSb possesses temperature- and magnetic field-dependent dielectric properties. The replacement of polyimide dielectric layer with InSb provides near unity absorption of 99.99 % at B = 0.4 T but when the effect of temperature on the absorption is taken, it provides a high absorptivity of 99.99 % at T = 285 K with a blue shift in the maximum resonance frequency, providing tunability of 0.016 THz/K on increasing the temperature from 280 K to 295 K. Thus, the proposed absorber not only provides dual control over the resonance spectrum but also progresses towards more practical applications in the sensing and detection of temperature variance.

Transport of orbital currents in systems with strong intervalley coupling: The case of Kekulé distorted graphene

We show that orbital currents can describe the transport of orbital magnetic moments of Bloch states in models where the formalism based on valley current is not applicable. As a case study, we consider Kekulé-OO distorted graphene. We begin by analyzing the band structure in detail and obtain the intrinsic orbital magnetic moment operator of Bloch states for this model. Despite the simultaneous presence of time-reversal and spatial-inversion symmetries, such operator may be defined, although its expectation value at a given energy is zero. Nevertheless, its presence can be exposed by the application of an external magnetic field. We then proceed to study the transport of these quantities. In the Kekulé-OO distorted graphene model, the strong coupling between different valleys prevents the definition of a bulk valley current. However, the formalism of the orbital Hall effect together with the non-Abelian description of the magnetic moment operator can be directly applied to describe its transport in these types of models. We show that the Kekulé-OO distorted graphene model exhibits an orbital Hall insulating plateau whose height is inversely proportional to the energy band gap produced by intervalley coupling. Our results strengthen the perspective of using the orbital Hall effect formalism as a preferable alternative to the valley Hall effect approach.

Stabilization of magneto-Rayleigh-Taylor instability with non-uniform density and magnetic field profiles in Cartesian Geometry

Managing the Rayleigh–Taylor instability growth rate is one of the main challenges in inertial fusion. Among the proposed methods to tackle this issue, the application of a pre-embedded axial magnetic field and plasma density gradient of layers can be mentioned. Recent experimental evidence in Z-pinch devices shows that it is possible to suppress the growth rate of the Rayleigh-Taylor instability by applying a power law density gradient profile with exponent 2. In this work, in the framework of Cartesian coordinates, for a confined plasma between two fixed planes, the dispersion relation of a magnetized plasma has been obtained using linearization of the ideal MHD equations. Here, plasma with a power-law density profile of ∝r3 and magnetic field with the exponential profile is used. It is shown that for the relative strength of the magnetic field with a value of, ωf*=0.4 and more, the growth rate of instability appears only in a limited range of the range of reduced wave numbers, k*. By increasing this ratio, stability conditions are much improved. On the other hand, recent experimental studies show that self-generated plasma rotation is produced in an imploding Z-pinch device with an initial axial magnetic field. In the second part, the effect of plasma rotation on plasma stability conditions is investigated. Again, a new dispersion relation of the rotating magnetized plasma was derived. It is shown that in the non-magnetized case, a large relative angular velocity, Ω, is necessary to suppress the instability. However, for relative magnetic field strength, ωf*=0.4 and more, stable conditions can be achieved with a relatively lower angular velocity of about 5.

The effect of irrigation with magnetized wastewater on soil heavy metals, water productivity and heavy metals in aerial parts and grains of maize

Rising population strains food resources; reusing wastewater increases but brings microbial and heavy metal pollution, impacting nature and human health. Among environmental pollutants, heavy metals in wastewater are a major concern. Using magnetized water is a method to improve water and soil quality. The aim of this research is to investigate the effect of using treated magnetized wastewater on the chemical properties and tracking of heavy metals in the soil, performance and yield components, water efficiency, and absorption of heavy metals by maize plant. Irrigation treatments consisted of various water and wastewater blending ratios under both magnetic and non-magnetic field application conditions. The results showed that the effect of irrigation water and mixing of water and wastewater on electrical conductivity, soil salts and heavy metals in different depths were significant at 1% probability level. On average, irrigation with magnetized wastewater caused a significant increase in grain yield (9.8%) and biological yield of maize (10.63%) compared to non-magnetized wastewater treatment. Irrigation with magnetized wastewater caused a significant increase in biological (10.92%) and physical (10.13%) productivities compared to non-magnetized wastewater treatment. With applying a magnetic field resulted in a reduction of 17.99%, 23.25%, 17.86%, and 17.12% in the concentration of lead, cadmium, zinc, and nickel in the aerial parts of the plant, respectively, compared to the non-magnetized water treatment. Magnetized water increases the water use efficiency of maize and irrigation management with this technology can be useful in more effective and economical use of limited water resources.

DMF-DM-seq: Digital-Microfluidics Enabled Dual-Modality Sequencing of Single-Cell mRNA and microRNA with High Integration, Sensitivity, and Automation.

Multimodal measurement of single cells provides deep insights into the intricate relationships between individual molecular layers and the regulatory mechanisms underlying intercellular variations. Here, we reported DMF-DM-seq, a highly integrated, sensitive, and automated platform for single-cell mRNA and microRNA (miRNA) co-sequencing based on digital microfluidics. This platform first integrates the processes of single-cell isolation, lysis, component separation, and simultaneous sequencing library preparation of mRNA and miRNA within a single DMF device. Compared with the current half-cell measuring strategy, DMF-DM-seq enables complete separation of single-cell mRNA and miRNA via a magnetic field application, resulting in a higher miRNA detection ability. DMF-DM-seq revealed differential expression patterns of single cells of noncancerous breast cells and noninvasive and aggressive breast cancer cells at both mRNA and miRNA levels. The results demonstrated the anticorrelated relationship between miRNA and their mRNA targets. Further, we unravel the tumor growth and metastasis-associated biological processes enriched by miRNA-targeted genes, along with important miRNA-interaction networks involved in significant signaling pathways. We also deconstruct the miRNA regulatory mechanisms underlying different signaling pathways across different breast cell types. In summary, DMF-DM-seq offers a powerful tool for a comprehensive study of the expression heterogeneity of single-cell mRNA and miRNA, which will be widely applied in basic and clinical research.

Exploring efficiency in next generation high temperature superconducting-enhanced applied field magnetoplasmadynamic thrusters: A combined numerical and experimental study

The integration of superconductors into space propulsion has emerged as a promising avenue. Superconductors have demonstrated significant effectiveness in space propulsion devices in terms of performance. This study introduces a low-power High-Temperature superconducting Applied Field MPD thruster, utilizing High-Temperature superconductors to propel plasma out of the thruster to generate thrust. Replacing traditional copper magnets with High-Temperature superconducting magnets has not only led to substantial improvements but has also addressed challenges such as the increased weight of traditional copper coils, the energy-intensive nature of copper magnets consuming high power, and the extremely low temperatures required by conventional superconductors, necessitating the use of helium cooling tanks, which can add to the overall weight of the thruster.The research combines numerical simulations with detailed experimental validation to evaluate performance. As predicted by the simulation model, experimental results demonstrate a thrust of 220 mN at 15 mg/s and 15.2 kW, and 180 mN at 5 mg/s and 14.8 kW, with a specific impulse of 2760s, while maintaining a discharge current of 200 A. Additionally, the discharge voltage in the experimental setup increases with magnetic field strength but decreases with mass flow rate. Plasma fall voltage also increases with both the applied magnet field strength set by the High-Temperature superconducting magnet and the mass flow rate. Meanwhile, the fractional electrode fall voltage decreases with the applied field. Discharge voltage, plasma fall voltage, and electrode fall voltage are analyzed as factors influencing the increase or decrease in thrust, specific impulse, and efficiency of the High-Temperature superconducting-enhanced Applied Field Magnetoplasmadynamic thruster.Furthermore, the study concludes with a comprehensive examination of the High-Temperature superconducting-enhanced Applied Field Magnetoplasmadynamic thruster, offering valuable insights for researchers. Notably, the achieved efficiencies for Applied field Magnetoplasmadynamic thruster at low input power surpass those of the same configuration with traditional copper magnet, highlighting the potential benefits of utilizing High Temperature superconducting magnets for enhanced performance.

The effects of the magnetic field on germination and seedling growth of chickpea (Cicer arietinum L.) and sunflower (Helianthus annuus L.)

Organisms interact with their environment and effects of environmental factors vary depending on ecology and tolerance levels. However magnetic field is an inevitable factor for all organisms. The aim of the study was to investigate the effects of different magnetic field (MF) applications on germination percentage, pigment content and antioxidant capacity of two important agricultural plant (Sunflower and Chickpea) species. Initially, seeds were exposed to 5 mT, 10 mT and 20 mT magnetic field generated by Helmholtz coil for detection of germination effects. Then seedling test was survived at the same conditions. MF was applied 20 minutes for every day at the same time period. According to germination results, MF application to sunflower and chickpea seeds was resulted with increase in germination percentage compared to control. 20 mT application caused decrease in shoot length of sunflower seedlings. On the contrary, 20 mT MF application resulted with increase in shoot length of chickpea seedlings. All magnetic field strengths increased carotenoid levels in chickpea seedlings. Also, MF application affected the phenolic and flavonoid contents of sunflower and chickpea seedlings. Depending on the increase in secondary metabolites, DPPH and FRAP activities varied. As a conclusion, MF application contributed to effect on plant metabolism and it has the potential to be used in agricultural applications.

What Effects Do Magnetic Fields Exert on the Bioaccumulation of Galanthamine and Lycorine, Growth Efficiency, Capacity to Scavenge Free Radicals, and Defense Enzyme Activities of Summer Snowflakes (Leucojum aestivum L.)?

Leucojum aestivum L. is a bulbous Amaryllidaceae family plant. A pot experiment was conducted to investigate the impact of three different magnetic field (MF) intensities [50, 100 and 150 militesla (mT)] with three different exposure durations (1, 3 and 7 days) on growth parameters, alkaloid levels (galanthamine and lycorine), non-enzymatic antioxidant activities (total phenol-flavonoid content and free radical scavenging activity), and enzymatic antioxidant activities [superoxide dismutase (SOD) and catalase (CAT)] compared with control (no MF) in the bulbs and leaves. Maximum bulb length was achieved with 150 mT MF application for 3 days. Galanthamine levels increased by 63% in the bulbs with 150 mT-7 days exposure and by 79.8% in the leaves with 50 MT-1 day exposure compared to the control. The leaves and bulbs with 100 mT exposure showed the greatest increases in lycorine concentrations (23.8% and 62.3% rises, respectively). MF exposures of 150 mT for 3 days gave the best radical scavenging activity and total phenol-flavonoid content. The highest alkaloid levels in the bulbs were associated with higher SOD and CAT activity generated by MF treatments. This study revealed that the medicinal value and quantity of L. aestivum bulbs could be significantly increased with 150 mT MF intensity.

Nanoscale Visualization of Symmetry-Breaking Electronic Orders and Magnetic Anisotropy in a Kagome Magnet YMn6Sn6.

A kagome lattice hosts a plethora of quantum states arising from the interplay between nontrivial topology and electron correlations. The recently discovered kagome magnet RMn6Sn6 (R represents a rare-earth element) is believed to showcase a kagome band closely resembling textbook characteristics. Here, we report the characterization of local electronic states and their magnetization response in YMn6Sn6 via scanning tunneling microscopy measurements under vector magnetic fields. Our spectroscopic maps reveal a spontaneously trimerized kagome electronic order in YMn6Sn6, where the 6-fold rotational symmetry is disrupted while translational symmetry is maintained. Further application of an external magnetic field demonstrates a strong coupling of the YMn6Sn6 kagome band to the field, which exhibits an energy shift discrepancy under different field directions, implying the existence of magnetization-response anisotropy and anomalous g factors. Our findings establish YMn6Sn6 as an ideal platform for investigating kagome-derived orbital magnetic moment and correlated magnetic topological states.

Free convective and radiating flow confined between vertical parallel MHD plates with heat transfer and uniform inclined magnetic field

The objective of this article is to investigate on the natural convective MHD flow of viscous fluid with assessment of mass and heat transfer effects. The flow is confined by two parallel plates. The walls of plates are assumed to be porous. The thermal radiation effects and inclined magnetic field applications are endorsed. One plate maintains the adiabatic phenomenon. The simplified form of problem is achieved with help of dimensionless variables. The analytical outcomes for given formulated problem are obtained with help of perturbation technique. Effects of various flow parameters involving to the problem are graphically impacted. It is claimed that velocity profile enhances due to modified Grashof number. An enhancement in heat transfer is subject to increasing the radiation parameter. Moreover, concentration profile reduces due to Reynolds number.

Magnetic field‐assisted electrocatalysis: Mechanisms and design strategies

AbstractElectrocatalysis has received a great deal of interest in recent decades as a possible energy‐conversion technology involving a variety of chemical processes. External magnetic field application is a powerful method for improving electrocatalytic performance that is customizable and compatible with existing electrocatalytic devices. In addition, magnetic fields can assist in catalyst synthesis and act on the catalytic reaction process. This paper systematically reviews the most recent developments in magnetic field‐assisted electrocatalytic enhancement technology. The enhancement of electrocatalysis by a magnetic field is mainly represented in the three features listed below: The spin selectivity effect improves the activity of the catalyst in a magnetic field; furthermore, magnetic fields can improve mass transport and electron transport in catalytic processes (due to Lorentz forces, Kelvin forces, magnetohydrodynamic [MHD], and micro‐MHD); the magnetothermal effect may raise the reaction temperature and boost electrocatalytic activity. This review focuses on the rational design of catalytic systems incorporating the interaction between catalysts and magnetic fields, aiming to produce enhanced catalytic effects. The recommendations for further utilization of strategies for electrocatalysis and broader energy technologies for magnetic fields, as well as potential challenges for future research, are also discussed.

Influence of the external magnetic field on structural characteristics of granular Co-Cu thin film alloys

We present the results of experimental studies of the influence of an external magnetic field on the structural characteristics (surface roughness and structural entropy) of nanogranular thin-film system based on Co and Cu. The samples CoxCu100-x in a wide range of compositions (17 at. % ≤ x ≤ 69 at. %) with the thickness of d = 35 nm were obtained by electron-beam co-evaporation using two independent electron guns. After obtaining, the films were annealed in a vacuum at a temperature of 800 K for 30 min. The studies of magnetoresistive properties have shown that the maximum giant magnetoresistance (GMR) amplitude (1.7 % in the transverse and 1.6 % in the longitudinal measurement geometries) in a magnetic field of H = 4.5 kOe at room temperature was observed in the Co21Cu79 film alloy. Transmission electron microscopy showed that this sample contains hcp-Co granules with a size of L = 5 ÷ 12 nm in a matrix of metastable fcc-Cu(Co) solid solution. The influence of the external magnetic field on the structural characteristics and surface morphology of the Co21Cu79 thin-film alloy was investigated using atomic force microscopy (AFM). It was found that a first impact of application of external magnetic field with H = 0.5 kOe causes a decrease in the values of the arithmetic mean Ra, and quadratic mean Rq, of the film roughness and structural entropy S. A decreases in Ra by 8.5 %, Rq by 6.5 %, and structural entropy S by 6.5 % were observed. After application of a larger magnetic field with H = 1.0 kOe and during the subsequent relaxation of the structure within 15 h after the field is turned off, the values of the structural parameters of the film surface did not change significantly.

A setup for synchrotron infrared microspectroscopy and imaging under magnetic field and low temperature.

Infrared spectroscopy is a powerful spectroscopic technique for investigating the vibrational and electronic states of matter. Temperature and magnetic field provide important methods to manipulate these states by an external field. Recent advancements have underscored the necessity for investigating small samples like two-dimensional materials with high spatial resolution. In this article, we introduce a versatile setup at the synchrotron infrared beamline, which combines synchrotron infrared microspectroscopy and imaging techniques with the application of magnetic fields and low temperature conditions. This setup facilitates infrared microscopic imaging in magnetic fields up to 8T and temperatures as low as 5K, offering a distinctive tool for probing the physical properties of materials under magnetic field and temperature manipulation. This is particularly relevant for studying two-dimensional materials, single cells, and other small samples in geoscience and environmental science, as well as multi-component heterogeneous properties in quantum materials, polymer materials, energy materials, etc.

Study of the effect of magnetic fields on static degradation of Fe and Fe-12Mn-1.2C in balanced salts modified Hanks’ solution

Iron and its alloys are attractive as biodegradable materials because of their low toxicity and suitable mechanical properties; however, they generally have a slow degradation rate. Given that corrosion is an electrochemical phenomenon where an exchange of electrons takes place, the application of magnetic fields from outside the body may accelerate the degradation of a ferrous temporary implant. In the present study, we have investigated the effect of alternating and direct low magnetic field (H = 6.5 kA/m) on the corrosion process of pure iron (Fe) and an iron-manganese alloy (FeMnC) in modified Hanks' solution. A 14-day static immersion test was performed on the materials. The corrosion rate was assessed by mass and cross-sectional loss measurements, scanning electron microscopy, X-ray diffractometry, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy before and after degradation. The results show that the presence of magnetic fields significantly accelerates the degradation rate of both materials, with the corrosion rate being twice as high in the case of Fe and almost three times as high for FeMnC. In addition, a homogenous degradation layer is formed over the entire surface and the chemical composition of the degradation products is the same regardless of the presence of a magnetic field.

Enhanced metamagnetic shape memory effect in Heusler-type Ni37Co11Mn43Sn9 polycrystalline ferromagnetic shape memory alloy

Polycrystalline Ni-Co-Mn-Sn based ferromagnetic shape memory alloys (FSMAs) show promise as actuator materials, but their practical application involving magnetic field induced strain (MFIS) is often limited by three factors: the requirement for high magnetic fields (> 5 T), martensitic transition temperature away from room temperature, and limited recovery of pre-strain applied to the martensite phase. Current work investigates the martensitic transition and shape memory effect under the application of magnetic field for bulk polycrystalline Ni37Co11Mn43Sn9 alloy. The outcome of the study reveals a metamagnetic transition from the martensitic phase to the austenitic phase at a low field of 2.8 T at 300 K which results 0.25 % spontaneous MFIS. Interestingly, 1.3 % pre-strained specimen registers a 100 % recovery with the application of magnetic field of 4.5 T. Furthermore, the pre-strained specimen exhibited a two-way shape memory effect between a strain value of 1.0 % to 1.55 % during the field loading and unloading sequences. Notably, this study demonstrates, for the first time to the best of our knowledge that the spontaneous MFIS and pre-strain add together. This finding paves the way for achieving a giant MFIS by pre-straining a Ni-Mn-Sn/In class of FSMAs which shows large spontaneous MFIS.

Spintronic device in SWCNT-FET configuration based on chromium oxides thin films consisting of half-metallic ferromagnetic CrO2

Spintronic device architectures consisting of ferromagnetic chromium oxide electrodes in single-walled carbon nanotubes field effect transistor (SWCNT-FET) configuration have been fabricated to act as strategic building blocks for next generation super-compact high-speed nanoelectronic devices for logic and memory operations. Stable thin films of chromium oxides consisting of half-metallic ferromagnetic chromium-di-oxide (CrO2) were pulsed laser deposited (PLD) over lattice-matched rutile-type-tetragonal intermediate TiO2 thin layers over thermally oxidized Si substrates for engineering of the spintronic device structure. Focused ion beam (FIB) milling was applied to the ferromagnetic chromium oxide thin films for patterning of the source (S) and (D) electrodes. Typical electrical characteristics derived by lnρ vs. T−1/2 plots confirmed spin-dependent transport (SDT) as the dominant mechanism of electrical conduction upto temperatures of ∼280 K along with negative magnetoresistance (MR) of ∼30 % at 278 K. Electrical characteristics (output and transfer) of the spintronic device structure were drawn under application of magnetic field (H) in out-of-plane geometry at the temperatures of 5.6 K, 250 K & 300 K. Drain current (Id) is demonstrated to be controlled effectively as a function of gate bias (Vg) for different fixed Vd-biases at all the device operating temperatures. Change in %MR as a function of gate voltage (Vg) was acquired at T = 250 &T = 300 K that displayed higher %MR change under out-of-plane geometry of applied field of 0.75 T of the spintronic device operation.