Ferromagnetic Chain Research Articles

Skyrmion motion monitoring based on a ferromagnetic nanodot chain

As one of the most promising information carriers, the generation, manipulation, and detection of magnetic skyrmions have emerged as a hot topic in the field of spintronics. However, a major bottleneck to their practical application lies in the existing limitations of detection technology, which fails to accurately locate skyrmions or monitor their real-time motion behavior. In this work, we propose a patterned heterostructure scheme comprising a nanodot chain (NDC) layer and a skyrmion nano-racetrack layer for precise monitoring of skyrmion motion. By exploiting the stray field generated by the moving skyrmion within the racetrack layer, magnetization changes are induced in nanodots within the NDC layer. These changes then translate into high-frequency magnetization oscillation signals that encode valuable information about the dynamic characteristics of driven skyrmions, such as speed and acceleration of the skyrmion, either by spin waves or spin currents. This scheme holds great potential for advancing spintronic devices based on a profound understanding of skyrmion dynamics.

Evolution of two-magnon bound states in a higher-spin ferromagnetic chain with single-ion anisotropy: A complete solution

Evolution of two-magnon bound states in a higher-spin ferromagnetic chain with single-ion anisotropy: A complete solution

Pioneering the plethora of soliton for the (3+1)-dimensional fractional heisenberg ferromagnetic spin chain equation

Abstract In this scholarly article, we investigate the complex structured (3+1)-dimensional Fractional Heisenberg Ferromagnetic Spin Chain equation (FHFSCE) with conformable fractional derivatives. We develop a diverse glut of soliton solutions using an improved version of the G ′ G -expansion method, namely the r + G ′ G -expansion method. The constraints for the existence of these solutions are painstakingly explained. Our findings are clearly communicated through a number of 3D and 2D graphical representations displaying periodic, multiple periodic, kink, and shock soliton solutions. These soliton solutions are expressed in several mathematical function forms, such as hyperbolic, trigonometric, and rational functions. Our findings support the suggested method’s efficacy as a powerful symbolic algorithm for discovering innovative soliton solutions within nonlinear evolution systems.

Enhanced polishing characteristics of Al-6061 via composite magnetic abrasives (EIP–Al2O3) assisted hybrid CMMRF process

In magnetorheological (MR) fluid polishing, high magnet speed releases abrasive particles from the finishing region, reducing their grip on the ferromagnetic chain structure and triggering the process to stall. Enhancing polishing efficiency necessitates developing a new composite magnetic abrasive (EIP-Al2O3) through microwave sintering. EIP-Al2O3 has favourable soft magnetic effects when it comes to its structure, phase composition, magnetic, and rheological properties. Chemo-mechanical magneto-rheological finishing (CMMRF), a developed hybrid-finishing method, aims to thoroughly evaluate CMA's performance. CMA attains a defect-free Al-6061 surface with Ra ∼79 nm and MRR ∼0.379 mg/min. CMAs outperforms simply mixed abrasives (SMA) by a significant 25 % increase in Ra and a remarkable 60 % increase in MRR. CMAs emerges as an effective solution for combating tool aging effects at high rotational speeds.

Dynamical analysis and the soliton solutions of (2+1)-dimensional Heisenberg ferro-magnetic spin chains model with beta fractional derivative

This paper investigates the soliton solutions and dynamical analysis of (2+1)-dimensional Heisenberg ferro-magnetic spin chains model with beta fractional derivative, which is transformed into the ordinary differential equation. By using the second-order complete discriminant system, the soliton solutions are presented. By utilizing the theory of planar dynamical system, the phase portraits of the dynamical system and its disturbance system are drawn. Moreover, three-dimensional, two-dimensional, and contour plots of soliton solutions for (2+1)-dimensional Heisenberg ferro-magnetic spin chains model with beta fractional derivative have also been plotted.

Thermoelectric Phenomena in a Magnetic Heterostructure with AAH Modulation: Charge and Spin Figure of Merits

ABSTRACT We put forward a prescription of getting a higher value of the spin-dependent figure of merit in comparison with its charge counterpart in the case of a 1D magnetic heterostructure (a ferromagnetic (FM) chain sandwiched between two non-magnetic 1D lattices) where all the site energies of the heterostructure follow cosine form of modulation defined in Aubry-Andre-Harper (AAH) model. It is shown that due to having a greater number of non-uniform peaks in its transmission spectra, the thermoelectric efficiency of this heterostructure becomes superior compared to that is obtained in a fully ferromagnetic 1D chain. It is also reported that the maximum value of the thermoelectric figure of merit (for both spin and charge-dependent cases) of the heterostructure in a specified energy range gets enhanced in a continuous manner as the disorder strength of the AAH modulation is increased. The Hamiltonian of the proposed quantum system is described within a tight-binding (TB) framework and after the evaluation of transmission probability by utilizing the non-equilibrium Green’s function (NEGF) technique, all the important thermoelectric quantities are determined on the basis of Landauer formalism. We believe that our study on this particular topic of spin caloritronics, a subject associated with temperature-dependent spin transmission through a quantum channel, may help to explore several fascinating ideas about spin-related thermoelectric efficiency in many other ferromagnetic quasicrystals.

Theory of Moiré Magnetism and Multidomain Spin Textures in Twisted Mott Insulator-Semimetal Heterobilayers.

Motivated by the recent experimental developments in van der Waals heterostructures, we investigate the emergent magnetism in Mott insulator-semimetal moiré superlattices by deriving effective spin models and exploring their phase diagram by Monte Carlo simulations. Our analysis indicates that the stacking-dependent interlayer Kondo interaction can give rise to different types of magnetic order, forming domains within the moiré unit cell. In particular, we find that the AB (AA) stacking regions tend to order (anti)ferromagnetically for an extended range of parameters. The remaining parts of the moiré unit cell form ferromagnetic chains that are coupled antiferromagnetically. We show that the decay length of the Kondo interaction can control the extent of these phases. Our results highlight the importance of stacking-dependent interlayer exchange and the rich magnetic spin textures that can be obtained in van der Waals heterostructures.

Analytical solutions and soliton behaviors in the space fractional Heisenberg ferromagnetic spin chain equation

This study investigates soliton solutions to the (2 + 1)-dimensional space fractional Heisenberg ferromagnetic spin chain equation incorporating beta fractional derivatives that explain the nonlinear propagation of spin wave in the ferromagnetic material with magnetic interactions including the both classical and semi-classical frameworks. This model has applications in spintronics, plasma physics, magnet theory, and condensed matter physics. Employing the two-potential extended Kudryashov and (G′/G, 1/G)-expansion methods, we derive some original and generic solutions composed of trigonometric functions, hyperbolic functions, and their rational forms. For particular values of the parameters, these solutions offer V-shaped, bell-shaped, kink, periodic, flat kink, and singular periodic solitons. The physical behavior of these solitons is demonstrated through three-dimensional, contour, and two-dimensional plots. The results are important in the study of phase transitions in ferromagnetic materials, lattice vibrations in condensed matter, and the propagation of shock waves in plasma. This study also demonstrates the potential and reliability of the employed strategies.

Polymeric dichlorido-bridged copper(II) offset stacked dimer coordination compounds and molecular spin stairs

A family of oxygen coordinated dichlorido-bridged n-X-2-pyridone (1, n = 3, X = Cl; 2, n = 3, X = Br; 3, n = 4, X = Cl; 4, n = 4, X = Br; 5, n = 5, X = Cl; 6, n = 5, X = Br) Cu(II) offset stacked dimer compounds, denoted molecular spin stairs, have been prepared and analyzed by single-crystal X-ray diffraction (1–4), powder X-ray diffraction (1–6), and variable temperature magnetic susceptibility measurements (1–6). Ferromagnetism is dominant in all compounds with a weaker antiferromagnetic exchange present in 1–4. The ferromagnetic exchange correlates to increased twist angles which are defined by the extent of the tetrahedral distortion of the copper coordination sphere and the identity of the halogen on the ring. The compounds were qualitatively fit to a ferromagnetic Heisenberg chain model with a Curie-Weiss interchain correction. The general Hamiltonian used is of the form H = − J ∑ S 1 S 2 . The ratio of exchange energies denoted α ( α = J FM | J AFM | ) ranges between 2.6 and 4.7. This family of compounds constitutes possible S = ½ Haldane-like materials.

Collision of perturbed soliton in discrete ferromagnetic spin chain with nearest neighbor and next nearest neighbor Dzyaloshinskii–Moriya interaction

Collision of perturbed soliton in discrete ferromagnetic spin chain with nearest neighbor and next nearest neighbor Dzyaloshinskii–Moriya interaction

Magnetic order in holmium and erbium formate: Parent frameworks for a potential random spin chain paramagnet

This work uses a combination of neutron diffraction and bulk property measurements to establish the low temperature magnetic states in the dense metal-organic frameworks Ho(HCO2)3 and Er(HCO2)3; whose structures feature chains of face-sharing LnO9 polyhedra packed into a triangular lattice. Below 0.7 K Ho(HCO2)3 is found to adopt a state in which the magnetic moment on its ferromagnetic chains vary from neighbouring chains but the sum around each triangle is constant. Er(HCO2)3 is found to be the first lanthanide formate to adopt an ordered magnetic state with antiferromagnetic coupling within its chains near 50 mK. The potential to combine the ferromagnetic and antiferromagnetic coupling within chains associated with Ho and Er cations, respectively, in the same compound has also been explored via the series Ho1-xErx(HCO2)3. Ho0.5Er0.5(HCO2)3 remains paramagnetic to 0.4 K, suggesting it may be a starting point to search for a random spin chain paramagnet.

Magnetic transition of 1D ferromagnetic catalysts during the NO electroreduction

Exploration of magnetic phase transitions during electrochemical processes is of great importance for rational design of supported magnetic-metal electrocatalysts. Herein, we systematically investigated the magnetic transition between ferromagnetism (FM) and anti-ferromagnetism (AFM) in one-dimensional ferromagnetic Co chain supported on graphene (Co4N8-gra) during NO electroreduction (NORR) process, focusing on the impact of potential and acidity on the catalytic property and magnetic transition. A combination of catalytic kinetics calculations and microkinetic simulations reveals that the Co4N8-gra exhibits excellent NH3 selectivity and thermal stability. In the implicit solvent model, the general reaction follows optimal pathway: * + NO(g) → *NO → *HNO → *H2NO → *H2NOH → *NH2 → *NH3 → * + NH3, with the potential-determining step (PDS) identified as *NO → *HNO. In acidic solvent, the magnetic transitions follow the pathway (FM → AFM2 → AFM2 → AFM2 → AFM1 → AFM1 → AFM1 → FM) under an applied potential of −0.20 V/RHE. In neutral solvent, the magnetic transitions occur according to this pathway (FM → AFM2 → AFM2 → FM → AFM1 → AFM1 → AFM1 → FM) under an applied potential of −0.14 V/RHE. In an alkaline solvent, the magnetic transitions proceed along this sequence (FM → AFM1 → AFM2 → FM → AFM1 → AFM1 → AFM1 → FM) under an ultralow potential of −0.08 V/RHE. Essentially, the improvement of catalytic property is attributed to the synergistic influence of external potential and magnetic-state transition on the adsorption of reaction species (e.g., NO and NH3). Magnetic transitions are closely associated with ligand field effect of metal site with variable valence electron induced by applied potential. In general, this study provides valuable insights for the controllable design of magnetic metal catalysts.

Quantum annealing of a frustrated magnet

Quantum annealing, which involves quantum tunnelling among possible solutions, has state-of-the-art applications not only in quickly finding the lowest-energy configuration of a complex system, but also in quantum computing. Here we report a single-crystal study of the frustrated magnet α-CoV2O6, consisting of a triangular arrangement of ferromagnetic Ising spin chains without evident structural disorder. We observe quantum annealing phenomena resulting from time-reversal symmetry breaking in a tiny transverse field. Below ~ 1 K, the system exhibits no indication of approaching the lowest-energy state for at least 15 hours in zero transverse field, but quickly converges towards that configuration with a nearly temperature-independent relaxation time of ~ 10 seconds in a transverse field of ~ 3.5 mK. Our many-body simulations show qualitative agreement with the experimental results, and suggest that a tiny transverse field can profoundly enhance quantum spin fluctuations, triggering rapid quantum annealing process from topological metastable Kosterlitz-Thouless phases, at low temperatures.

Semiclassical approach to spin dynamics of a ferromagnetic S = 1 chain

Abstract Motivated by recent experimental progress on the quasi-one-dimensional quantum magnet NiNb2O6, we study the spin dynamics of an S = 1 ferromagnetic Heisenberg chain with single-ion anisotropy by using a semiclassical molecular dynamics approach. This system undergoes a quantum phase transition from a ferromagnetic to a paramagnetic state under a transverse magnetic field, and the magnetic response reflecting this transition is well described by our semiclassical method. We show that at low temperature the transverse component of the dynamical structure factor depicts clearly the magnon dispersion, and the longitudinal component exhibits two continua associated with single- and two-magnon excitations, respectively. These spin excitation spectra show interesting temperature dependence as effects of magnon interactions. Our findings shed light on the experimental detection of spin excitations in a large class of quasi-one-dimensional magnets.

Long-range magnon transfer across a bridging ferromagnetic chain via sequential and tunnel routes

A theoretical study of the mechanism of magnon transfer through a ferromagnetic chain (F) has been carried out from magnetically ordered contact A to similar contact B (AFB system). The regime of spin excitation transport is considered, when the inner section of the chain with identical paramagnetic units acts as a bridge for magnon transfer and thereby is poorly populated by magnons. In this case, the magnon transfer can be carried out by sequential hopping the localized magnon across all units of the chain or/and tunneling the magnon between the terminal units of the chain by a “superexchange” mechanism. The latter involves in the tunneling route the virtual delocalized magnons. The analytical dependence of the corresponding transfer rates on the number of paramagnetic bridge units is found and the magnon analog of the Seebeck and Peltier effects is predicted.

Ferromagnetic polymers arising from magnetic and Coulombic interactions

We propose a model to investigate the magnetic behavior in the ferromagnetic polymer chain. Namely, the polymer consists of alternating single and double bonds, with Coulomb (Hubbard) intra-site interaction. Each repeat unit is further attached to a magnetic functional group, where the magnetic coupling between on-chain spin-polarized itinerant charges and localized magnetic moments of the size group is included. We found that dimerization opens a band gap in the polymers and is closely related to magnetism. Besides, the weakly linked magnetic functional groups can simultaneously increase the initially weak Coulomb interaction and the magnetic coupling to create significant magnetism in such ferromagnetic polymers. However, the strongly linked magnetic functional groups for creating ferromagnetic polymers can provide robust orbital coupling and produce significant orbital splits, but weak ferromagnetism of low-spin states appears. Moreover, choosing the light magnetic functional groups to link polymers can make effective dimerization as well as ferromagnetism. Furthermore, adding hole density to the polymers for increasing mobility does not have the same effect on rising Curie temperatures. Instead, a maximum Curie temperature appears on a specific hole density.

Spin dynamic soliton in ferromagnetic materials over the (2 + 1)-dimensional beta fractional HFSC model

Ferromagnetic materials have important exploitation practice in permanent information in electromagnets, electric motors, generators, recording in thin film etc. This research explores spin dynamic soliton in Ferromagnetic materials via the (2 + 1)-D Heisenberg ferro-magnetic Spin Chains (HFSC) model. The Extended (I,R) and Extended Simple schemes treatment are applied to integrate the model. Through the technique, various novel dynamical wave solutions afford as optical dark and bright soliton envelope, spin wave envelope Black soliton, optical bell-shock interaction, optical bell-anti-shock wave, optical Dark-bright bell soliton and optical bright periodic waves from modulus plots, besides these real and imaginary profiles exhibits bright periodic wave with dark bell wave, periodically increasing–decreasing carrier wave, periodic carrier wave increase its amplitude by shock, periodic carrier wave suddenly decrease its amplitude by shock waves. The effect of fractional derivative, neighboring interaction as well as uniaxial crystal field anisotropy parameters is explored on the envelope soliton and amplitude of carrier waves. The changing value of neighboring interaction parameters are exhibited as increases wave height with the increases of parametric values, but while increasing values of the uni-axial crystal arena anisotropy factor causes the reduction of wave heights.

Thermal transitions in a one-dimensional, finite-size Ising model

We revisit the one-dimensional ferromagnetic Ising spin chain with a finite number of spins and periodic boundaries, deriving analytically and verifying numerically its various stationary and dynamical properties at different temperatures. In particular, we determine the probability distributions of magnetization, the number of domain walls, and the corresponding residence times for different chain lengths and magnetic fields. While we study finite systems at thermal equilibrium, we identify several temperatures similar to the critical temperatures for first-order phase transitions in the thermodynamic limit. We illustrate the utility of our results by their application to structural transitions in biopolymers having non-trivial intermediate equilibrium states.

Magnetoelectric CoV2O6—Role of Fe inter-play in Co-based Ising spin chain interactions

CoV2O6, a Brannerite-type material, exists in both monoclinic (α) and triclinic (γ) forms. α- CoV2O6 exhibits quasi-1D ferromagnetic chains of octahedrally-coordinated Co2+ions in the higher spin state. Fe2+ doped α-CoV2O6 (3 mol%) single crystals were synthesized using high temperature melt method. The motivation is to investigate whether disruption of 1D Co2+ ferromagnetic chains by small Fe3+ substitution alters the antiferromagnetic ground state and lead to stronger spin-frustration. In this paper, we report the magnetic and magnetodielectric properties of Fe doped α-CoV2O6 in detail. The strongly anisotropic nature of magnetic and magnetodielectric characteristics were captured well in the data through orientation dependent measurements with H being parallel to a and c axes of the crystal. Relative dielectric permittivity (εr) exhibited sharp peaks coinciding with the plateau edges Hc1 ∼2.2 T and Hc2 ∼4.4 T in the magnetization curves (M-H) for applied H parallel to a-axis. For dielectric measurements under applied H parallel to c-axis, relative dielectric permittivity exhibited sharp peak around Hc2 ∼3.1 T, again coinciding with the M-H behavior. Such closely related magnetic field induced dielectric transitions reflected in both M(H) and εr(H) measurements is a rare phenomenon and representative of strong spin-lattice coupling in this phase.

Analytical approaches to the (2+1)-dimensional Heisenberg Ferromagnetic Spin Chain equation and their applications for optical devices

Analytical approaches to the (2+1)-dimensional Heisenberg Ferromagnetic Spin Chain equation and their applications for optical devices