Applications In Magnetic Devices Research Articles

Development of magnetic (Fe–Ga) multi-layered thin films for applications in magnetic sensor devices

Development of magnetic (Fe–Ga) multi-layered thin films for applications in magnetic sensor devices

Excellent magnetic properties in multiferroic BiFeO3 based thin films for magnetic devices application

The operation of magnetic devices with a magnetic field or spin current causes high energy consumption. Very low energy consumption can be achieved by using multiferroic thin films, where we can control the magnetization direction by applying an electric field. Good magnetic properties in multiferroic thin films are needed for these magnetic device applications. However, multiferroic thin films generally do not have such good magnetic characteristics, like high saturation magnetization (Ms), perpendicular magnetic anisotropy (PMA, the ratio of coercivity between the alignment of film plane perpendicular and parallel to the applied field (Hc⊥/Hc//)), magneto-optical Kerr rotation angle (Θk) and Curie temperature (Tc). In this research, we have looked into improving magnetic characteristics such as Ms, Hc⊥/Hc//, Θk and Tc in (Bi,L)(Fe,Co)O3(L = Lanthanides) thin films by substituting different lanthanides with cobalt. The highest Ms value of 140 emu/cm3 and large Hc⊥/Hc// ratio of 2.6 were found in (Bi,Nd)(Fe,Co)O3 thin film, and maximum Θk of 0.67° and relatively high Hc⊥/Hc// of 1.6 were found for the (Bi,La)(Fe,Co)O3 thin film. These properties are suitable for magnetic recording devices and optical devices, respectively. A very small coercivity of 0.8 kOe, along with a high Ms value of 110 emu/cm3 and Tc of 450 °C, were observed in the (Bi,Eu)(Fe,Co)O3 thin film. So, the (Bi,Eu)(Fe,Co)O3 thin film is suitable for magnetic sensor applications because of its high sensitivity to magnetic fields. Moreover, the domain size of the above-mentioned thin films was observed in the small nano range, which is suitable for magnetic nano device applications.

Synthesis of polyacene by using a metal–organic framework

The acene series, an important class of linearly polycyclic aromatic hydrocarbons, are of interest owing to their unique physicochemical features. With an increase in the number of fused benzene rings, acenes display an evolution of electronic structure and properties. Thus, efforts have been devoted to the synthesis of longer acenes, with dodecacene being the longest acene (12 fused benzene rings) reported to date. However, the formation of polymeric acenes with numerous benzene rings, namely polyacene, has yet to be realized. Herein, we present a methodology for the synthesis of polyacene mediated by a metal–organic framework. Nanoconfined synthesis of precursor polymers in the channels of the metal–organic framework and the subsequent dehydro-aromatization reaction produced polyacene that was overwhelmingly longer than the previously reported acenes. The scalable synthesis of polyacene allowed us to unveil the stability and electronic properties of polyacene, paving the way for their widespread applications in optoelectronic and magnetic devices.

Review of: "The Application of Adjustable Magnetic Devices in Electric Power Systems"

Review of: "The Application of Adjustable Magnetic Devices in Electric Power Systems"

Controlling In‐Plane Magnetic Anisotropy of Co Films on MgO Substrates using Glancing Angle Deposition

The ability to control the in‐plane magnetic anisotropy of a thin film is important for magnetic device applications. One way of accomplishing this task is by glancing angle deposition (GLAD). Herein, thin Co layers have been deposited using GLAD magnetron sputtering on MgO(001) and MgO(110) substrates. For Co films on MgO(001), the in‐plane anisotropy direction can be directly controlled via the deposition angle. In contrast, for Co on MgO(110), the anisotropy due to the deposition angle competes with the anisotropy induced by the substrate, while the growth parameters determine which contribution dominates. On the other hand, while on MgO(001) the deposition angle as well as the film thickness affect the strength of the Co in‐plane anisotropy, no influence of these parameters on the magnetic properties is found for films on MgO(110).

Review of: "The Application of Adjustable Magnetic Devices in Electric Power Systems"

Review of: "The Application of Adjustable Magnetic Devices in Electric Power Systems"

The Evolving Use of Magnets in Surgery: Biomedical Considerations and a Review of Their Current Applications.

The novel use of magnetic force to optimize modern surgical techniques originated in the 1970s. Since then, magnets have been utilized as an adjunct or alternative to a wide array of existing surgical procedures, ranging from gastrointestinal to vascular surgery. As the use of magnets in surgery continues to grow, the body of knowledge on magnetic surgical devices from preclinical development to clinical implementation has expanded significantly; however, the current magnetic surgical devices can be organized based on their core function: serving as a guidance system, creating a new connection, recreating a physiologic function, or utilization of an internal-external paired magnet system. The purpose of this article is to discuss the biomedical considerations during magnetic device development and review the current surgical applications of magnetic devices.

Efficient Spin-Orbit Torque Switching in a Perpendicularly Magnetized Heusler Alloy MnPtGe Single Layer.

Electrically manipulating magnetic moments by spin-orbit torque (SOT) has great potential applications in magnetic memories and logic devices. Although there have been rich SOT studies on magnetic heterostructures, low interfacial thermal stability and high switching current density still remain an issue. Here, highly textured, polycrystalline Heusler alloy MnxPtyGe (MPG) films with various thicknesses are directly deposited onto thermally oxidized silicon wafers. The perpendicular magnetization of the MPG single layer can be reversibly switched by electrical current pulses with a magnitude as low as 4.1 × 1010Am-2, as evidenced by both the electrical transport and the magnetic optical measurements. The switching is shown to arise from inversion symmetry breaking due to the vertical composition gradient of the films after sample annealing. The SOT effective fields of the samples are analyzed systematically. It is found that the SOT efficiency increases with the film thickness, suggesting a robust bulk-like behavior in the single magnetic layer. Furthermore, a memristive characteristic has been observed due to a multidomain switching property in the single-layer MPG device. Additionally, deterministic field-free switching of magnetization is observed when the electric current flows orthogonal to the direction of the in-plane compositional gradient due to the in-plane symmetry breaking. This work proves that the MPG is a good candidate to be utilized in high-density and efficient magnetoresistive random access memory devices and other spintronic applications.

Comparative analysis of the electronic structure and magnetic properties of Zn(1-x)Tmx Se(Tm = Fe, V) using LDA and LDA+U approximations

In this article, we present the electronic structure and magnetic properties of Zn(1-x)TmxSe (Tm = Fe, V) by density functional theory (DFT) as employed in a quantum espresso. The properties were examined using the local density approximation (LDA) and Hubbard correction (LDA + U), where U is a Hubbard parameter. The calculated ZnSe lattice parameter is 5.58 Å, which is very close to the experimental result of 5.66 Å. In this study, the LDA + U provides a better band gap approximation for ZnSe (Eg = 1.4212 eV) than the LDA (Eg = 1.2507 eV), which is consistent with values previously reported. The results confirm that antiferromagnetic and ferromagnetic property tunability can be achieved in an iron-doped ZnSe system, where as the ferromagnetic property is conistent over a wide temperature range in a vanadium-doped zinc selenide, which agrees with experimental results. Based on additional experimental results, it is possible to consider these materials for the application of spintronics and magnetic devices.

Entropy generation phenomenon for ciliated pumping flow of aluminum oxide and silver nanoparticles with Hall device significances

The study of hybrid nanomaterials subject to the magnetic force and Hall device applications presents many novel applications in the chemical engineering and biomedical domains. This study theoretically investigates the physical features of two-dimensional flow of hybrid fluid via ciliated pumping through a micro-tube. This investigation deals with the performance of aluminum oxide and silver nanoparticles in viscous (water) flow enclosed in a complex ciliated tube. Physical effects of Hartmann number, Hall parameter, volumetric concentration of nanoparticles, ciliated length parameter, Brinkman number, and temperature difference parameter. The impacts of embedded parameters in the velocity profile, pressure gradient, heat transfer, entropy generation, and Bejan number are explored. The larger strength of Hall parameter overcomes the physical impacts of the magnetic device. The absorption of nanoparticles has a remarkable role in the flow features. Additionally, the ciliated length parameter has a significant role in the enhancement of the velocity profile, pressure gradient, and temperature profile. The comprehensive investigation has dynamic applications in the thermos-electric cells, transportation of biological liquids through uniform and non-uniform vessels, nanotechnologies, chemical processes, and mobility of the red blood cells.

Crystal structure and magnetic property correlations in Ba1−x Sr x Fe12O19 (0 ≤ x ≤ 1) hexaferrites

This paper reports a comprehensive study on the structure-property correlations in strontium-substituted barium hexaferrite and their suitability for possible applications at room temperature. A series of samples, Ba1−x Sr x Fe12O19 (0 ≤ x ≤ 1) synthesized by citrate-based sol-gel auto-combustion technique, were characterized by various physicochemical characterization techniques. The x-ray diffraction data of these samples ensure the single-phase formation and the variation of crystallographic parameters as a function of strontium substitution was discussed. The decrease in lattice parameters with increasing strontium (x) substitution ensures the applicability of Vegard’s law for the present system. The scanning electron micrographs reveal some of the grains in hexagonal shape in these samples. Raman data revealed the interconnection between magnetic ion site occupancies and the corresponding magnetization contributions, thereby ensuring the structure-property correlations in these samples. As these hexaferrites consist of layers of (ferro- and antiferro-) magnetic domains, the sub-lattice magnetic contributions were estimated by fitting the magnetic hysteresis loops (M − H) data using theoretical models. The magnetization versus temperature (M − T) graphs confirmed the above room-temperature ferromagnetic behavior. This study clearly reveals that proper tuning of their structural properties can result in optimal magnetic properties, making them suitable for permanent magnet and room-temperature magnetic device applications.

Synthesis of Two-Dimensional MoO2 Nanoplates with Large Linear Magnetoresistance and Nonlinear Hall Effect.

Two-dimensional (2D) materials with large linear magnetoresistance (LMR) are very interesting owing to their potential application in magnetic storage or sensor devices. Here, we report the synthesis of 2D MoO2 nanoplates grown by a chemical vapor deposition (CVD) method and observe large LMR and nonlinear Hall behavior in MoO2 nanoplates. As-obtained MoO2 nanoplates exhibit rhombic shapes and high crystallinity. Electrical studies indicate that MoO2 nanoplates feature a metallic nature with an excellent conductivity of up to 3.7 × 107 S m-1 at 2.5 K. MoO2 nanoplates display a large LMR of up to 455% at 3 K and -9 T. A thickness-dependent LMR analysis suggests that LMR values increase upon increasing the thickness of nanoplates. Besides, nonlinearity has been found in the magnetic-field-dependent Hall resistance, which decreases with increasing temperatures. Our studies highlight that MoO2 nanoplates are promising materials for fundamental studies and potential applications in magnetic storage devices.

DFT+U study on the magnetic properties of 3d transition metal doped β borophene

Two-dimensional materials with strong magnetism have attracted extensive attention for their potential application in spintronics. Recently, thess β 12 borophene with stable structure has been successfully synthesized experimentally. However, the β 12 borophene with non-magnetism limits its application in spintronics. The structural, electronic and magnetic properties of pristine and 3d transition metal (TM)-doped β 12 borophene monolayers are studied by means of first-principles calculations based on the GGA + U approach. Our results indicate that the doping of the Ti-, V-, Cr-, Mn-, Fe-, Co- and Ni atoms can induce magnetism in β 12 borophene and comparatively large magnetism can be obtained in Cr-, Mn-, Fe- and Co-doped systems. The Cr-, Mn- and Co-doped β 12 borophene exhibit antiferromagnetic ground states, while ferromagnetic ground state occurs in the Fe-doped system. Particularly, the spin density distribution of the Cr- and Mn-doped β 12 borophene is highly localized, which have a promise for application in magnetic storage devices. Our work provides a valuable theoretical guidance for the further experimental study and application of borophene materials in spintronics. • The doping of the Ti-, V-, Cr-, Mn-, Fe-, Co- and Ni atoms can induce magnetism in β 12 borophene and comparatively large magnetism can be obtained in Cr-, Mn-, Fe- and Co-doped systems. • The Cr-, Mn- and Co-doped β 12 borophene systems exhibit antiferromagnetic ground states, while ferromagnetic ground state occurs in the Fe-doped system. • The spin density distribution of the Cr- and Mn-doped β 12 borophene is highly localized, which have a promise for application in magnetic storage systems.

Ferromagnetism Induced by Magnetic Dilution in Van der Waals Material Metal Thiophosphates

AbstractMetal thio(seleno) phosphates MPX3 attract considerable attention with potential application in spintronics and other types of devices. Here, ferromagnetism in an Ising type diluted magnetic semiconductor Fe1‐xZnxPS3 is reported. Bulk single crystals of Fe1‐xZnxPS3 have been synthesized via chemical vapor transport method and characterized by X‐ray diffraction. The weak ferromagnetism associated with spin/cluster spin glass emerges at 30% Zn doping. A nearly static ferromagnetic order is observed in the highly diluted magnets Fe0.1Zn0.9PS3. X‐ray photoemission measurements indicate introduction of holes and associated Fe3+ in samples with ferromagnetic order. Density functional theory calculations confirm the Ising‐type ferromagnetic state in highly diluted compounds with hole doping. The interplay between bound magnetic polarons induces impurity‐band‐exchange and superexchange interactions can explain the evolution of magnetism with Zn doping. The findings suggest that the magnetic diluted FePS3 system is a candidate for potential applications in magnetic devices, and its quantum mechanism should be explored by using microscopic techniques in the near future.

On the synthesis and characterization of bimagnetic CoO/NiFe2O4 heterostructured nanoparticles

Bimagnetic nanoparticles show promise for applications in energy efficient magnetic storage media and magnetic device applications. The magnetic properties, including the exchange bias of nanostructured materials can be tuned by variation of the size, composition, and morphology of the core vs overlayer of the nanoparticles (NPs). The purpose of this study is to investigate the optimal synthesis routes, structure and magnetic properties of novel CoO/NiFe2O4 heterostructured nanocrystals (HNCs). In this work, we aim to examine how the size impacts the exchange bias, coercivity and other magnetic properties of the CoO/NiFe2O4 HNCs. The nanoparticles with sizes ranging from 10 nm to 24 nm were formed by synthesis of an antiferromagnetic (AFM) CoO core and deposition of a ferrimagnetic (FiM) NiFe2O4 overlayer. A highly crystalline magnetic phase is more likely to occur when the morphology of the core-overgrowth is present, which enhances the coupling at the AFM-FiM interface. The CoO core NPs are prepared using thermal decomposition of Co(OH)2 at 600 °C for 2 hours in a pure argon atmosphere, whereas the HNCs are obtained first using thermal evaporation followed by hydrothermal synthesis. The structural and morphological characterization made using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), and scanning electron microscopy (SEM) techniques verifies that the HNCs are comprised of a CoO core and a NiFe2O4 overgrowth phase. Rietveld refinement of the XRD data shows that the CoO core has the rocksalt (Fd3 m) crystal structure and the NiFe2O4 overgrowth has the spinel (C12/m1) crystal structure. SEM-EDS data indicates the presence and uniform distribution of Co, Ni and Fe in the HNCs. The results from PPMS magnetization measurements of the CoO/NiFe2O4 HNCs are discussed herein.

Size-dependent magnetic properties of Mn-Co-NiO based heterostructured nanoparticles

In this work, we investigate the synthesis, along with the structural and magnetic properties, of novel Mn-Co-NiO-based heterostructured nanocrystals (HNCs). The objective is to develop novel, well-structurally ordered inverted antiferromagnetic (AFM) NiO–ferrimagnetic (FiM) spinel phase overgrowth HNCs. Inverted HNCs are particularly promising for magnetic device applications because their magnetic properties are more easily controlled by having well-ordered AFM cores, which can result in magnetic structures having large coercivities, tunable blocking temperatures, and other enhanced magnetic effects. The synthesis of the HNCs is accomplished using a two-step process: In the first step, NiO nanoparticles are synthesized using a thermal decomposition method. Subsequently, Mn-Co overgrowth phases are grown on the NiO nanoparticles via hydrothermal nanophase epitaxy, using a fixed pH level (∼5.3) of the aqueous medium. This pH level was selected based on previous work in our laboratory showing that NiO/Mn3O4 HNCs of constant size have optimal coercivity and exchange bias when synthesized at a pH of 5.0. The crystalline structure and gross morphology of the Mn-Co-NiO-based HNCs have been analyzed using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques, respectively. Analysis using these techniques shows that the HNCs are composed of a NiO core and a CoMn2O4 overgrowth phase. Rietveld refinement of XRD data shows that the NiO core has the rocksalt (Fm3̄m) cubic crystal structure and the CoMn2O4 overgrowth has the spinel (I41/amd) crystal structure. Moreover, an increased relative amount of the CoMn2O4 overgrowth phase is deposited with decreasing NiO core particle size during the synthesis of the HNCs. The results from PPMS magnetization and high-resolution transmission electron microscopy (HRTEM) characterization of the Mn-Co-NiO-based HNCs are discussed herein.

Relative magnetic field and slipping effect on Casson dusty fluid of two phase fluctuating flow over inclined parallel plate

Due to its significant applications in magnetic devices for cell separation, magnetic drugs for cancer tumor treatment, blood flow adjustment during surgery, magnetic endoscopy, and fluid pumping in industrial and engineering processes, magnetohydrodynamics (MHD) has a wide range of applications. Therefore, the aim of this study to investigate the Relative Magnetic Field and slipping effect on Casson dusty fluid of two-phase fluctuating flow over inclined parallel plate. More exactly, the relative magnetic phenomena are fixed relatively to the plate (MFFRP) or fixed relatively to the fluid (MFFRF). The mathematical modeling was established as the set of partial differential equations for dusty Casson fluid. Buckingham's pi theorem is used to find out the dimensionless variables, to make our system dimensionless. The solution in perturb form is to find out by incorporating Poincare–Lighthill perturbation technique (PLPT). To know in-depth different parameters the graphical results for both velocities are plotted with the help of software Mathcad- 15. It is clearly detected that the relative magnetic field performs a vital part in the fluid as well as particle motion. Moreover, the relative magnetic field play a vital role in the decreasing of skin friction of both plates.

Effect of La and Se in tailoring the energy storage properties of BFO nanostructures

Simultaneous rare-earth doping at A and B sites have impacted various properties of BFO at room temperature. In this work, the dielectric and magnetic properties of BFO, are tailored by doping La and Se. Bi0.92La0.08Fe1−xSexO3, (x = 0%, 10%, 25%, 50%, 100%) nanostructures are prepared using sol-gel technique. Structural analysis reveals that increased doping has reduced and eliminated the secondary phases of nanostructures. Absorption spectra showed a wide blue shifted absorption, indicating multiple electron transitions and the bandgap values decreased upon doping. Improved room temperature dielectric properties with increased doping indicates these nanostructures as viable candidates in energy storage applications. The improvements in ac-conductivity, impedance and modulus spectrum of doped nanostructures are observed. Specific capacitance of 36.22 F/g for Bi0.92La0.08Fe1O3 at 10 mV/s and 21.48F/g for the Bi0.92La0.08Fe0.9Se0.1O3 sample was observed. Weak ferromagnetism is observed in M-H loops with increased Se concentration that also finds applications in magnetic storage devices.

Growth morphology and magnetic properties of Gd adatoms on h-BN template: From single atom to small cluster and monolayer

Atomic assembly of surface-supported nanostructures with high structural stability, large magnetic moment and magnetic anisotropy energy (MAE) hold great potential applications in spintronic and magnetic storage devices. With the changes of deposition coverage of Gd adatoms on the hexagonal boron nitride (h-BN) template, we systemically investigate the low-lying structures and magnetic properties of Gdn (n=1–19) clusters and monolayers (1ML-Gd and 2ML-Gd) by combining various theoretical methods including the spin–orbital coupling (SOC) density functional theory (DFT), abinitio molecular dynamics (AIMD) simulations and lattice dynamical calculations. Favorable adsorption sites and preferable orientations as well as distinguishing electronic structures have been thoroughly explored to reveal the bonding characteristics and growth models of Gd clusters and thin films. We demonstrate that the planar Gd clusters/monolayers deposited on h-BN surface can exhibit the energetically, dynamically, thermally, and thermomagnetically stable at high temperature of 500 K. The Gd-B covalent and ionic bonding interactions instead of Gd-N interactions give the synergetically contributions for stabilizing small clusters on planar h-BN sheet via the hybridizations of Gd-5d and B-2pz orbitals, while Gd-N covalent bonds participate in additionally bonding interaction for the depositions of large clusters on corrugated h-BN sheet due to the transformations from B/N-sp2 to B/N-sp3 hybridizations. Robust ferromagnetic (FM) couplings with large spin magnetic moments about 7.6 μB per Gd atoms are always found to be the ground states. Orbital magnetic moments of −0.10∼−0.37 μB per atom and large MAEs in few meV are primarily contributed by Gd-5d electrons. We propose that the Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction mediated by 5d electrons determines the long-term FM coupling between Gd atoms, and we estimate the Curie temperatures ranging from 150 K to 60 K for different Gd deposited systems. The excellent structural and magnetic stability as well as large magnetic moment and MAEs therefore facilitate Gd cluster and thin film the promising candidates for spintronic applications.

Co‐ and Nd‐Codoping‐Induced High Magnetization in Layered MoS2 Crystals

Magnetic 2D‐layered materials are promising for the applications of spintronic devices and compact magnetic devices. There are only a few reported intrinsic 2D‐based magnetic materials. Therefore, introducing magnetic element into 2D‐layered materials is an effective strategy to synthesize 2D‐layered magnetic materials. Recently, ferromagnetism has been realized by doping single transition‐metal or rare‐earth element, whereas, there is no report by codoping of both transition‐metal and rare‐earth elements. Herein, Co and Nd are codoped into MoS2‐layered crystals by ion implantation. An extremely high magnetization of 6916.3 emu cm−3 at 10 K and 80.3 emu cm−3 at 300 K is achieved. The high magnetization is attributed to the contribution from both transition‐metal and rare‐earth elements as well as defects, such as vacancy of cation ions, anions, or interstitials. Hence, herein, a useful strategy may be opened to develop high‐performance magnetic materials based on 2D‐layered materials.