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The sol-gel auto-composition approach was used to produce AgxCo0.5−xZn0.5Fe1.95La0.05O4/5% G (x = 0, 0.01, 0.05, 0.1, 0.25, 0.5 (nanocomposites. Some techniques for characterizing the composite structure such as XRD, SEM, EDX, HR-TEM, SAED, FTIR, Raman, and electron mapping are performed. The structure is indexed to be cubic ferrite with space group Fd-3 m lattice parameters ranging from (8.3823–8.4139 A˚). The crystallite size was determined by four trends to be (27.57–41.72 nm), (30.88–62.18 nm), (80.70–103.6 nm), and (73.12 nm) by Scherer's equation, W-H relation, SEM, and HR-TEM respectively. The strain ε and the line dislocation δ in crystalline and the theoretical density ρXRD are evaluated. EDX and elemental mapping revealed that all elements are present, indicating a good synthesis method. FTIR spectrum shows octahedron absorption band ʋocta at 399–462 cm− 1 and the tetrahedron band tetra at 590–624 cm− 1. The force constant kOct. and kTet. octahedral and tetrahedral are determined to be 1.1854 × 105 and 2.0249 × 105 dyne/cm. The VSM approach estimates the magnetic characteristics of such materials to be ferromagnetic, with a saturation magnetization of 44.60 emu/g decreasing with increasing Ag concentration. The Hc is in 117.95 G, which decreases to 25% with increasing Ag content. Graphene-based nanoparticles offer unique mechanisms of action and broad-spectrum activity against bacteria and cancer cells. The effect of a novel and inventive chemical on gram-positive and gram-negative bacteria was examined. The compound exhibited a significant antibacterial effect on gram-positive bacteria, with a 60% activity compared to the control and 64% activity on gram-negative. Furthermore, the antifungal activity has been evaluated. It also exhibited a great cytotoxic activity on the MDA-MB-231breast cancer cell line, leading to decreased viability by 94.5%, 93.26% and 90.1% for Ag = 0.5, 0.1, and 0, respectively, compared with negative control. Continued study and development in this sector may result in the creation of novel treatment techniques for fighting bacterial infections and cancer. This paper provides a comprehensive study of the current knowledge regarding utilizing zinc, Silver, and cobalt in the context of their antibacterial and anticancer activities. [ABSTRACT FROM AUTHOR]

We report high throughput computational screening for magnetic ground state order in 2D materials. The workflow is based on spin spiral calculations and yields the magnetic order in terms of a two-dimensional ordering vector Q. We then include spin-orbit coupling to extract the easy and hard axes for collinear structures and the orientation of spiral planes in non-collinear structures. Finally, for all predicted ferromagnets we compute the Dzyaloshinskii-Moriya interactions and determine whether or not these are strong enough to overcome the magnetic anisotropy and stabilise a chiral spin spiral ground state. We find 58 ferromagnets, 21 collinear anti-ferromagnets, and 85 non-collinear ground states of which 15 are chiral spin spirals driven by Dzyaloshinskii-Moriya interactions. The results show that non-collinear order is in fact as common as collinear order in these materials and emphasise the need for detailed investigation of the magnetic ground state when reporting magnetic properties of new materials. [ABSTRACT FROM AUTHOR]

Neuromorphic computing offers energy‐efficient computations for large‐scale data processing compared to conventional von Neumann computing. The artificial synapse, a key element for learning and memory operations in neuromorphic computing, requires multi‐state characteristics and the capability to change and store its states. The implementation of hardware‐based artificial synapses using nonvolatile memory provides significant advantages in terms of energy consumption and circuit area compared to their currently employed CMOS‐based counterparts. In this regard, spintronic devices have emerged as a promising candidate due to their desirable properties for artificial synapses, including multilevel formability, non‐volatility, and outstanding writing performance. In this study, spintronic artificial synapses utilizing voltage‐controlled multilevel magnetic states and energy‐ and area‐efficient artificial neural network architectures associated with them are demonstrated. The multilevel states are created by gradually modulating the magnetic easy‐axis orientation from perpendicular to in‐plane and vice versa, which is achieved either by sequentially applying gate voltage pulses or by adjusting the pulse width of the gate voltage. Based on these spintronic artificial synapses, convolutional neural network (CNN) and spiking neural network (SNN) architectures are constructed, demonstrating high recognition accuracy for the MNIST dataset with improved energy efficiency and a reduced circuit area. [ABSTRACT FROM AUTHOR]

In this paper, vacuum annealing has been adopted to introduce atomic cluster micro-regions inside Gd-based metallic microfibers to further explore the effect of the structural changes on the magnetocaloric properties and the mechanism which is systematically expressed. The experimental results indicate that the as-prepared Gd-based metallic microfibers have favorable amorphous formation ability and thermal stability. After annealing @ 380 °C, the maximum magnetic entropy change −ΔSmmax, refrigerating capacity (RC), and relative cooling power (RCP) values of the Gd-based metallic microfibers are 7.20 J/kg·K, 459.4 J/kg, and 588.7 J/kg, respectively. Combined with the transmission electron microscopy analysis results, the internal organizational order of the annealed microfibers is significantly altered, and the atomic clusters formed in localized regions, which reduce the magnetocrystalline anisotropy of the microfibers. While under the uni-action of an external magnetic field, the magnetic moment rotation state and magnetic domain structure distribution of the micro-region atoms will be changed obviously, thereby changing the general magnetic properties and magnetocaloric properties of the metallic microfibers. The above research results can promote the engineering application of Gd-based metallic microfibers in the field of magnetic refrigeration. [ABSTRACT FROM AUTHOR]

The domain wall energy is calculated by the balance between exchange, magnetocrystalline anisotropy and magnetoelastic energy contributions. The described method is theoretical and is based on experimental measurements of neutron inelastic scattering. The domain wall energy is determined by both finding the minimum of energy and deriving the energy and setting it to zero. The determination was undertaken for the discrete case, and this means that the calculation was performed for each plane or atomic layer. This is in contrast with the Bloch wall, which assumes continuum mean. The energy of the Lilley domain wall was discussed. Most of the energy of the Bloch wall was comprised inside the Lilley distance (above 99.9% of the energy). Antiferromagnetic interactions strongly decreased the domain wall energy. The negative terms due to antiferromagnetism must be considered in the Hamiltonian describing the exchange energy terms. The domain wall energy and width of terbium were reassessed. The values varied between 83.7 and 95.2 Kelvin (10.3 to 11.2 ergs/cm2). The domain width was estimated to be 57 Angstroms. It was found that a significant part of the total domain wall energy was concentrated on the planes at the center of the domain wall. [ABSTRACT FROM AUTHOR]

Enantiomeric molecules generally play distinct functions in chemistry, biology, and pharmacology. Similar physical and chemical properties of chiral analytes lay difficulty in discrimination and quantification of the enantiomers. We report herein an efficient approach of increasing the chiral sensing ability of β-cyclodextrin (β-CD), a widely used host molecule, in the host-guest chemistry by magnetic anisotropy. A rigid and chiral lanthanide binding tag was attached to the β-CD to amplify the changes of nuclear magnetic resonance (NMR) signals in the host-guest recognition process. The installation of the paramagnetic lanthanide ion in β-CD greatly enhances the enantiomeric discrimination up to 30-fold in comparison with the diamagnetic β-CD reference. In addition, the magnitude of the paramagnetic effects is tunable according to the diverse range of paramagnetic strength of the lanthanide series. The reported method significantly increases the chiral sensing ability of β-CD, which can be applied to other host molecules. The transferred paramagnetic effects, pseudocontact shifts (PCSs) and paramagnetic relaxation enhancements (PREs), from the host to the guest molecules, are valuable structural restraints to determine the absolute stereochemistry of the chiral analytes. The strategy does not need modification of the analytes and is complementary to the reported analytical methods that rely on the functionalization of the chiral analytes. [ABSTRACT FROM AUTHOR]

Multistate memory systems have the ability to store and process more data in the same physical space as binary memory systems, making them a potential alternative to existing binary memory systems. In the past, it has been demonstrated that voltage-controlled magnetic anisotropy (VCMA) based writing is highly energy-efficient compared to other writing methods used in non-volatile nano-magnetic binary memory systems. In this study, we introduce a new, VCMA-based and skyrmion-mediated non-volatile ternary memory system using a perpendicular magnetic tunnel junction (p-MTJ) in the presence of room temperature thermal perturbation. We have also shown that ternary states {− 1, 0, + 1} can be implemented with three magnetoresistance values obtained from a p-MTJ corresponding to ferromagnetic up, down, and skyrmion state, with 99% switching probability in the presence of room temperature thermal noise in an energy-efficient way, requiring ~ 2 fJ energy on an average for each switching operation. Additionally, we show that our proposed ternary memory demonstrates an improvement in area and energy by at least 2X and ~ 104X respectively, compared to state-of-the-art spin-transfer torque (STT)-based non-volatile magnetic multistate memories. Furthermore, these three states can be potentially utilized for energy-efficient, high-density in-memory quantized deep neural network implementation. [ABSTRACT FROM AUTHOR]

Single-ion magnets (SIMs) are composed of 3d and/or 4f complexes with substantial energy barriers that inhibit spin reversal at the molecular level. The magnetic bistability of SIMs renders them promising for applications in quantum computing, high-density information storage, and molecular spintronics. Cobalt(II) ions are particularly advantageous among transition metals due to their high magnetic anisotropy, stability, and diverse coordination geometries. By integrating coordination frameworks with SIMs, a robust foundation has been established for the design and construction of novel molecular nanomagnets. This article provides an overview of single-ion magnetism within cobalt(II)-based coordination polymers, encompassing self-assemblies in one, two, and three dimensions. These findings underscore the potential of cobalt(II)-based coordination frameworks as a compelling platform for advancing the field of SIMs. [ABSTRACT FROM AUTHOR]

Switchable spin dynamic properties in single-molecule magnets (SMMs) via an applied stimulus have applications in single-molecule devices. Many SMMs containing heavy lanthanoid ions with strong uniaxial magnetic anisotropy have been reported to exhibit SMM characteristics in the absence of an external magnetic field. On the other hand, SMMs containing light lanthanoid cerium(III) (Ce3+) ions exhibit field-induced slow magnetic relaxation. We investigated the chemical conversion of a diamagnetic Ce4+ ion (4f0) to a paramagnetic Ce3+ ion (4f1) in Ce-phthalocyaninato double-decker complexes (TBA+[Ce(obPc)2]− (1) and TBA+[Ce(Pc)2]− (2)) which exhibit field-induced SMM behaviour due to a 4f1 system. The phthalocyaninato ligands with electron-donating substituents (obPc2− = 2,3,9,10,16,17,23,24-octabutoxyphthalocyaninato) in 1 have a significant effect on the valence state of the Ce ion, which is reflected in its magnetic properties due to the mixed valence state of the Ce ion. Given that Ce double-decker complexes with π-conjugated ligands undergo intramolecular electron transfer (IET) to the Ce ion mixed valence state, characterised by a mixture of 4f0 and 4f1 configurations, we examined the dynamic disorder inherent in IET influencing magnetic relaxation. [ABSTRACT FROM AUTHOR]

Hybrid metamaterials (HMs) have attracted significant research interests owing to their unique optical properties and their ability to manipulate light‐matter interaction in a novel and controlled fashion beyond what any single material offers. Especially 3D HMs are of great interest due to their potential to provide advanced and precise control of such light‐matter interaction in nanoscale. In this study, a set of 3D HM nanocomposite films are designed by integrating three phases, i.e., vertically aligned CoFe2 nanosheets within the matrix of TiN/TaN multilayers. By increasing the number of TiN/TaN multilayers from 2 to 19, a high degree of tunability in optical property has been demonstrated, including well‐tailored optical permittivity, and tunable hyperbolic dispersion from Type‐II to Type‐I. Ferromagnetic CoFe2 nanosheets introduces novel magnetic responses, such as magnetic anisotropy and enhanced coercivity. Furthermore, in situ heating X‐ray diffraction (XRD) suggests good thermal stability of the 3D nanocomposite films up to the measured temperature of 600 °C. This three‐phase 3D nanocomposite design offers more flexibility in HM designs, multifunctionalities, and phase stability, compared with the typical two‐phase HMs toward future metamaterials by design. [ABSTRACT FROM AUTHOR]

We report the laser-induced voltage (LIV) signals in cubic phase Sr3YCo4O10.5+δ (CP-SYCO) thin films with a c-axis tilted and discuss the relationship between the LIV signals and magnetic anisotropy. CP-SYCO thin films were epitaxially deposited on 0°, 5°, 10°, 15°, and 20° miscut LaAlO3 (001) substrates using pulsed laser deposition (laser energy of 200 mJ, post-annealed at 760 °C). The peak voltage of the LIV for the 15° tilted CP-SYCO film is 310 mV (under laser energy of 400 mJ/pulse), with a rising edge of 26 ns. Compared with G-type antiferromagnetic ordered tetragonal phase Sr3YCo4O10.5+δ(OT-SYCO, deposited at a laser energy of 300 mJ, post-annealed at 790 °C) film, the CP-SYCO exhibits much stronger magnetization anisotropy along in-plane and out-plane due to the possible A-type antiferromagnetic moment arrangement. CP-SYCO films also demonstrate significant thermoelectric anisotropy, supporting the transverse thermoelectric effect, which is partially attributed to the contribution of spin entropy. This study provides an understanding of the anisotropic behavior in atomic layer thermoelectric stack materials and explores magnetic anisotropic material systems. [ABSTRACT FROM AUTHOR]

In the future, DW memory will replace conventional storage memories with high storage capacity and fast read/write speeds. The only failure in DW memory arises from DW thermal fluctuations at pinning sites. This work examines, through calculations, the parameters that might help control DW thermal stability at the pinning sites. It is proposed to design a new scheme using a stepped area of a certain depth (d) and length (λ). The study reveals that DW thermal stability is highly dependent on the geometry of the pinning area (d and λ), magnetic properties such as saturation magnetization (Ms) and magnetic anisotropy energy (Ku), and the dimensions of the nanowires. For certain values of d and λ, DWs remain stable at temperatures over 500 K, which is beneficial for memory applications. Higher DW thermal stability is also achieved by decreasing nanowire thickness to less than 10 nm, making DW memories stable below 800 K. Finally, our results help to construct DW memory nanodevices with nanodimensions less than a 40 nm width and less than a 10 nm thickness with high DW thermal stability. [ABSTRACT FROM AUTHOR]

Our study of magnetization switching in crystalline (Ga,Mn)(As,P) ferromagnetic semiconductor (FMS) film by spin-orbit torque (SOT) has revealed an unexpected increase in critical switching current as the in-plane magnetic bias field is increased beyond a certain point. This intriguing behavior is ascribed to depolarization of spin-polarized current induced by the application of bias field perpendicular to the direction of current carrier spins. This is particularly interesting, because the bias field is itself a necessary requirement for achieving the deterministic SOT magnetization switching. To gain understanding of this unexpected behavior, we incorporated the process of spin depolarization into micromagnetic simulation study of SOT magnetization switching in the (Ga,Mn)(As,P) system. Through simulations that include effects of spin depolarization, we were able to replicate the observed increase in the required critical switching current as the in-plane bias field is increased. Furthermore, our study demonstrates that the dependence of critical switching current on bias field can be quantitatively described by adjusting magnetic anisotropy parameters of the film. This study not only enhances our understanding of SOT phenomena but also offers valuable insights for tailoring and optimizing FMS materials for spintronic applications. [ABSTRACT FROM AUTHOR]

We demonstrate the ability of a single magneto-optical reflection experiment to achieve layer-resolved vector magnetometry in multilayer films. For this purpose, we designed, fabricated, and measured a set of epitaxial ferromagnetic/non-magnetic/ferromagnetic heterostructure multilayer samples that exhibit in-plane uniaxial anisotropy and a tunable ferromagnetic interlayer coupling strength through the non-magnetic interlayer. By means of generalized magneto-optical ellipsometry measurements, we obtain the magnetization angles of the two different ferromagnetic layers independently as a function of the applied field. Hereby, we observe that the magnetization switching of one layer can trigger a discontinuous shift of the magnetization angle in the second layer if ferromagnetic interlayer coupling is present. Moreover, we reproduce the obtained behavior using a model of two coupled macrospins, which corroborates even the unexpected aspects of our experimental results and thus reinforces the sensitivity and reliability of our experimental layer-resolved vector magnetometry. [ABSTRACT FROM AUTHOR]

Due to their novel spin and valley properties, two-dimensional (2D) ferrovalley materials are expected to be promising candidates for next-generation spintronic and valleytronic devices. However, they are subject to various defects in practical applications. Therefore, the electronic, valley, and magnetic properties may be modified in the presence of the defects. In this work, utilizing first-principles calculations, we systematically studied the effects of defects on the electronic, valley, and magnetic properties of the 2D ferrovalley material VSi2N4. It has been found that C doping, O doping, and N vacancies result in the half-metallic feature, Si vacancies result in the metallic feature, and V vacancies result in a bipolar gapless semiconductor. These defect-induced electronic properties can be effectively tuned by changing defect concentration and layer thickness. Since the impurity bands do not affect the K and K′ valleys, valley polarization is well maintained in O-doped and N-defective systems. Importantly, these defects play a crucial role in modifying the magnetic properties of the pristine VSi2N4, especially the magnitude of local magnetic moments and the magnetic anisotropy energy. Detailed analysis of the density of states demonstrates that the variations of the total magnetic moment and magnetic anisotropy energy with biaxial strain are determined by the electronic states near the Fermi level rather than the type of defect, which provides a new understanding of the effects of defects on the magnetic properties of 2D materials. Moreover, the layer thickness can affect the magnetic coupling between defects and surrounding V atoms. Our results offer insight into the electronic, valley, and magnetic properties of VSi2N4 in the presence of various point defects. [ABSTRACT FROM AUTHOR]

The burgeoning interest in the field of molecular magnetism is to perceive the high magnetic anisotropy in different geometries of metal complexes and hence to draw a magneto-structural correlation. Despite a handful of examples to exemplify the magnetic anisotropy in various coordination geometries of mononuclear complexes, the magnetic anisotropies for two different coordination geometries are underexplored. Employing an appropriate synthetic strategy utilizing the ligand LH2 [2,2′-{(1E,1′E)-pyridine2,6-diyl-bis(methaneylylidine)}-bis(azaneylylidine)diphenol] and cobalt halide salts in a 1 : 2 stoichiometric ratio in the presence of triethylamine allowed us to report a new family of dinuclear cobalt complexes [Co II2 X2(L)(P)(Q)]·S with varying terminal halides [X = Cl, P = CH3CN, Q = H2O, S = H2O (1), X = Br, P = CH3CN, Q = H2O, S = H2O (2), X = I, P = CH3CN, and Q = CH3CN (3)]. All these complexes are characterized through single crystal X-ray crystallography, which reveals their crystallization in the monoclinic system P21/n space group with nearly identical structural features. These complexes share vital components, including Co(II) centers, a fully deprotonated ligand [L]2−, halide ions, and solvent molecules. The [L]2− ligand contains two Co(II) centers, where phenolate oxygen atoms bridge the Co(II) centers, forming a Co2O2 four-membered ring. Co1 demonstrates a distorted pentagonal-bipyramidal geometry with axial positions for solvent molecules, while Co2 displays a distorted tetrahedral geometry involving phenolate oxygen atoms and halide ions. Temperature-dependent dc magnetic susceptibility measurements were conducted on 1–3 within a range of 2 to 300 K at 1 kOe. The χmT vs. T plots exhibit similar trends, with χmT values at 300 K higher than the spin-only value, signifying a significant orbital contribution. As the temperature decreases, χmT decreases smoothly in all the complexes; however, no clear saturation at low temperatures is observed. Field-dependent magnetization measurements indicate a rapid increase below 20 kOe, with no hysteresis and a low magnetic blocking temperature. DFT and CASSCF/NEVPT2 theoretical calculations were performed to perceive the magnetic interaction and single-ion anisotropies of Co(II) ions in various ligand-field environments. [ABSTRACT FROM AUTHOR]

Due to their novel spin and valley properties, two-dimensional (2D) ferrovalley materials are expected to be promising candidates for next-generation spintronic and valleytronic devices. However, they are subject to various defects in practical applications. Therefore, the electronic, valley, and magnetic properties may be modified in the presence of the defects. In this work, utilizing first-principles calculations, we systematically studied the effects of defects on the electronic, valley, and magnetic properties of the 2D ferrovalley material VSi2N4. It has been found that C doping, O doping, and N vacancies result in the half-metallic feature, Si vacancies result in the metallic feature, and V vacancies result in a bipolar gapless semiconductor. These defect-induced electronic properties can be effectively tuned by changing defect concentration and layer thickness. Since the impurity bands do not affect the K and K′ valleys, valley polarization is well maintained in O-doped and N-defective systems. Importantly, these defects play a crucial role in modifying the magnetic properties of the pristine VSi2N4, especially the magnitude of local magnetic moments and the magnetic anisotropy energy. Detailed analysis of the density of states demonstrates that the variations of the total magnetic moment and magnetic anisotropy energy with biaxial strain are determined by the electronic states near the Fermi level rather than the type of defect, which provides a new understanding of the effects of defects on the magnetic properties of 2D materials. Moreover, the layer thickness can affect the magnetic coupling between defects and surrounding V atoms. Our results offer insight into the electronic, valley, and magnetic properties of VSi2N4 in the presence of various point defects. [ABSTRACT FROM AUTHOR]

The stable MnS monolayer was recently predicted using first-principles density functional theory (DFT) including Hubbard U (DFT+U) correction and Monte Carlo (MC) simulations. It is shown to exhibit an indirect band gap of 0.68 eV semiconductor with a high Neel temperature (TN) of 720 K and an in-plane easy axis magnetic anisotropy energy (MAE). The considered on-site Hubbard U correction takes into account only the Mn (3d) localized nature. To correct the intersite errors due to strong hybridization between bonded Mn (3d) and S (2p) states, the Hubbard +V inter-site parameter should be added to the calculations. In this study, the band gap of MnS is found to be increased to 1.24 eV (twice that for DFT+U) after considering the inter-site V correction (DFT+U+V). Since the MnS monolayer prefers an in-plane easy axis for the MAE, the estimated Berezinskii Kosterlitz Thouless transition (BKT) transition temperature is as high as 1667.8 K. The carrier mobility is calculated based on the deformation potential and effective mass and it is found that holes (2.12 cm²v-1S-1) are twice the size of these electrons (1.21 cm²v-1S-1). The results are expected to improve the potential of the MnS monolayers in multiple AFM spintronic device applications. [ABSTRACT FROM AUTHOR]

Lithium manganese nanoferrites (LixMn1–2xFe2+xO4, x = 0.0, 0.1, 0.2, 0.3, 0.4) are prepared by the chemical coprecipitation method. Magnetic properties of as-synthesized samples are investigated at room temperature using a vibrating-sample magnetometer. The superparamagnetic behavior of the samples is observed on the recorded M-H curves. From the hysteresis curve, saturation magnetization, coercivity, and retentivity are obtained. The squareness ratio, anisotropy constant and magnetic moment of the samples are calculated and compared. The cyclic voltammetry analysis is performed for different scan rates to determine the specific capacitance. The energy density and power density are calculated from the charge-discharge curve. The resistance to selected bacteria is analyzed using the antimicrobial activity test. [ABSTRACT FROM AUTHOR]

Mononuclear nickel complexes [NiL1(NCS)2]·2DMSO (I), [NiL1(NCS)2]·DMF (II), and [NiL2(NCS)2]·0.5CH3OH·1.5H2O (III) with the distorted octahedral coordination node, where L1 and L2 are the tetradentate ligand systems derived from the products of the condensation of diacetyl with 2-hydrazinoquinoline and 2-hydrazino-4,6-dimethylpyrimidine, respectively, are synthesized. The structures of the compounds are determined by IR spectroscopy and XRD (CIF files ССDС nos. 2219793 (I), 2142035 (II), and 2219794 (III)). The quantum chemical modeling of the axial parameter of magnetic anisotropy in the zero field (D) is performed for the synthesized compounds in the framework of the SA-CASSCF+NEVPT2 method. The complexes are shown to be characterized by three-axis magnetic anisotropy close to the light magnetization plane with positive D. The axial parameter of magnetic anisotropy (Dexp = 8.79 cm−1) determined by the approximation of the magnetometry data on complex [NiL2(NCS)2]·0.5CH3OH·1.5H2O is consistent with the calculated value (Dcalc = 11.5 cm−1). [ABSTRACT FROM AUTHOR]

Spin-transfer torque magnetic random access memory (MRAM) devices have considerable potential for high-performance computing applications; however, progress in this field has been hindered by difficulties in etching the magnetic tunnel junction (MTJ). One notable issue is electrical shorting caused by the accumulation of etching by-products on MTJ surfaces. Attempts to resolve these issues led to the development of step-MTJs, in which etching does not proceed beyond the MgO barrier; however, the resulting devices suffer from poor scalability and unpredictable shunting paths due to asymmetric electrode structures. This paper outlines the fabrication of pillar-shaped MTJs via a four-step etching process involving reactive-ion etching, ion-beam etching, oxygen exposure, and ion-trimming. The respective steps can be cross-tuned to optimize the shape of the pillars, prevent sidewall redeposition, and remove undesired shunting paths in order to enhance MTJ performance. In experiments, the proposed pillar-MTJs outperformed step-MTJs in key metrics, including tunneling magnetoresistance, coercivity, and switching efficiency. The proposed pillar-MTJs also enable the fabrication of MRAM cells with smaller cell sizes than spin–orbit torque devices and require no external field differing from voltage-controlled magnetic anisotropy devices. [ABSTRACT FROM AUTHOR]

This study introduces a method to measure the strength of spin–orbit interaction (SO) in a nanomagnet, investigating fundamental phenomena governing magnetic anisotropy. The method explores the fundamental property of SO in its linear proportionality to the external magnetic field, a relationship validated through experimental observation. Systematic study of SO in FeCoB nanomagnets reveals distinct SO behaviors in bulk and at an interface, substantial disparities in single- and multi-layer nanomagnets, intriguing periodic oscillations in SO strength, and the systematic relationship between SO strength, demagnetization field, and magnetic anisotropy based on surface imperfections. These findings provide crucial insights into diverse SO interaction behaviors, crucial for understanding and optimizing magnetic anisotropy and nanomagnet properties. [ABSTRACT FROM AUTHOR]

The exchange bias (EB) is a unidirectional magnetic anisotropy that is found in structures containing exchange-coupled ferromagnetic/antiferromagnetic interfaces. The EB usually manifests as a horizontal shift of the hysteresis after cooling the system through the Néel temperature of the antiferromagnet in the presence of an external magnetic field. A vertical shift and an asymmetry of the magnetization loop are also possible. At present, the EB is often investigated for its effect on an application in magnetic devices in a variety of material systems and applications. The EB bilayer systems Fe/FeF2 and Fe/MnF2 represent an interesting case of structural similarities. In this paper, we show that differences between magnetic material orders and disorder contributions, found at the microscale, make them model systems for the occurrence of specific magneto-crystalline anisotropies and specific angular dependencies of the EB with significant implications for magneto-electronic applications. [ABSTRACT FROM AUTHOR]

Angular-dependent magneto-optical Kerr effect (MOKE) and coplanar waveguide ferromagnetic resonance (CPW-FMR) measurements were performed to unravel the nature of anisotropy present in Ni 80 Fe 20 (Py) thin film. The "in-plane" angular variation of coercive field ( H c IP ) and resonance field ( H r IP ) confirms the magnetic anisotropy is negligible, where the spins are confined to the plane of the Py film. The variation of resonance field in "out-of-plane" geometry, H r OP , strongly indicates the presence of "out-of-plane" uniaxial anisotropy in the Py thin film. Also, the inverse spin Hall effect (ISHE) technique is employed to measure spin pumping-induced DC voltage, V ISHE , generated across the Py/Pt bilayer. The line shape analysis method has been utilized to distinguish ISHE and spin rectification contributions. The measured V ISHE at low (4 GHz) and high (35 GHz) frequencies confirm the pure spin current injected through the Py-Pt interface due to spin pumping using CPW-FMR setup, which has a direct bearing on the realization of quantum metrology through the spin current quantity. [ABSTRACT FROM AUTHOR]

This paper portrays the effect of growth rate on the structural, magnetic, and electrical properties of sputtered Ni thin films. Seventy-five nanometer thick Ni films were grown on Si <100> substrates at room temperature by high power impulse magnetron sputtering with varying growth rates such as 0.27, 0.57, 1.01, 2.18, and 2.65 Å/s. All the films crystallized in a single FCC type structure devoid of any impurity phase. With an increase in the growth rate, the density of the Ni films was found to increase. The surface roughness and the stresses developed in Ni films were found to decrease with an increase in the growth rate. Microstructural investigations indicated an island of surface morphology for all the films. An increase in growth rate was also found to affect the magnetic properties of Ni thin films considerably. Saturation magnetization increased with an increase in growth rate both along the in-plane and out-of-direction owing to the increase in the density of the film and reduction in stresses and surface roughness. Further, the in-plane magnetization studies also showed an increase in in-plane magnetic anisotropy in Ni films with an increase in growth rate. Evidences for improvement in the in-plane magnetic anisotropy were derived from the increase in the in-plane coercivity and remanence. Temperature variation of electrical resistivity in Ni films indicated a metallic behavior. Films grown at higher growth rates exhibited high-temperature co-efficient of resistance suitable for resistance temperature detector applications. [ABSTRACT FROM AUTHOR]

In this study, it was investigated the effect on the structural, and magnetic properties dependent on the thickness of the Nickel films grown on MgO (100) substrates by the molecular beam epitaxy at a high vacuum. The structural and magnetic properties were examined by using X-ray diffraction and ferromagnetic resonance techniques. The X-ray diffraction and X-ray reflectivity measurements showed that Ni films grew in (200) orientation with tiny surface roughness. Experimental ferromagnetic resonance data showed that all samples had in-plane easy axis from out-of-plane measurements and fourfold anisotropy from in-plane measurements. Additionally, conditions under which Ni/MgO (100) films grew epitaxially were also observed. In this study, where the minimum thickness required for some applications to exhibit both magnetic properties and form the crystal structure of Ni thin films is determined, the importance of film thickness in terms of applications is emphasized and the minimum thickness condition is determined in terms of some applications. [ABSTRACT FROM AUTHOR]

The nickel-iron-cobalt film with soft magnetic properties, having a minimal magnetocrystalline anisotropy and magnetostriction are applied in the magnetic sensors with giant magnetoresistance effect. In this work, single layers of Ni76Fe11Co13, Ni66Fe16Co18, and Ni56Fe21Co23 were coated by the electrochemical method, and then the results of the structural, magnetic, and electrical evaluation were discussed. An increase in the concentration of nickel in the electrolyte solution caused a change in the chemical composition, and morphology of the layers, and also reduced the coercive field. The layer containing 66 atomic percent nickel showed the lowest coercivity and the highest saturation magnetization. The single layers of Ni66Fe16Co18 were deposited on the copper substrate at different times. The results indicated that increasing the deposition time and thickness firstly decreased the coercive field up to 17 Oe, and then increased it up to 45 Oe for the Ni66Fe16Co18 layer. Also, multilayers of [NiFeCo/Cu]30 and [NiFeCo/Cu]60 were synthesized. An increase in the number of layers from 30 to 60 revealed a decrease in the coercive field from 43.1 Oe to 38.4 Oe, as well as an increase in the Mr/Ms squareness ratio from 0.46 to 0.51. The magnetoresistance of [NiFeCo/Cu]60 and [NiFeCo/Cu]30 multilayers indicated an electrical resistance reduction of about 15% and 6%, respectively. [ABSTRACT FROM AUTHOR]

Antiferromagnetic (AF) and ferrimagnetic (FiM) thin films have burgeoning significance in memory and computing applications due to their robustness and ultrafast and energy-efficient switching dynamics. Mn3Ga features a multitude of spin orders that can be meticulously controlled with stoichiometry, temperature, and strain modulations. In this work, we have carefully designed three suitable stacks of Mn3Ga thin films on MgO (111), STO (111) and STO (111)/Ta substrates deposited across varying substrate temperatures up to 500°C. The delicate interplay of strain and temperature tuning is examined by characterizing their magnetic, crystallographic, and morphological properties. The FiM tetragonal τ-Mn3Ga and AF hexagonal ε-Mn3Ga phases display relatively low saturation magnetizations of 10–60 and ≤ 20 kA/m, respectively. No preferential in-plane or out-of-plane magnetic anisotropy is observed for both τ- and ε-Mn3Ga phases. Critically, we observed that the STO strain-regulated τ-phase is stabilized over a wider temperature window and provides more compact, uniformly dispersed grains with average grain size of ~ 100 nm. This work establishes a sturdy methodology in understanding Mn3Ga thin film growth for eventual AF- and FiM-based memory and computing applications. [ABSTRACT FROM AUTHOR]

Recent developments in 2D magnetic materials have motivated the search for new van der Waals magnetic materials, especially Ising‐type magnets with strong magnetic anisotropy. Fe‐based MPX3 (M = transition metal, X = chalcogen) compounds such as FePS3 and FePSe3 both exhibit an Ising‐type magnetic order, but FePSe3 receives much less attention compared to FePS3. This work focuses on establishing the strategy to engineer magnetic anisotropy and exchange interactions in this less‐explored compound. Through chalcogen and metal substitutions, the magnetic anisotropy is found to be immune against S substitution for Se whereas tunable only with heavy Mn substitution for Fe. In particular, Mn substitution leads to a continuous rotation of magnetic moments from the out‐of‐plane direction toward the in‐plane. Furthermore, the magnetic ordering temperature displays non‐monotonic doping dependence for both chalcogen and metal substitutions but due to different mechanisms. These findings provide deeper insight into the Ising‐type magnetism in this important van der Waals material, shedding light on the study of other Ising‐type magnetic systems as well as discovering novel 2D magnets for potential applications in spintronics. [ABSTRACT FROM AUTHOR]

(Fe0.7Co0.3)2B are potential permanent magnets material due to its large saturation magnetization and high Curie temperature. However, it has moderate magnetocrystalline anisotropy (MCA) and low coercivity. One way to improve its coercivity is to combine the contributions from magnetocrystalline- and magnetic-shape anisotropy by preparing (Fe0.7Co0.3)2B nanowires. We study the effects of size, morphology, and surface defects on the hard magnetic properties of nanowires using micromagnetic simulation. The hard magnetic properties of (Fe0.7Co0.3)2B nanowire-bonded magnets are estimated, including the role of inter-wire magnetostatic interaction. By considering the existence of local reductions in MCA energy of up to 30% on the surface layer of nanowires, the anisotropic bonded magnet with a 65% vol. of (Fe0.7Co0.3)2B nanowires would have typical remanence, Br= 7.6–8.4 kG, coercivity, Hci= 9.6–9.9 kOe, and maximum energy product, (BH)m = 14–17.8 MGOe. Developing effective technology for synthesizing nanowires and fabricating corresponding bonded magnets is promising for manufacturing practical magnets based on the magnetic phase with a relatively low or moderate MCA, such as (Fe0.7Co0.3)2B. [ABSTRACT FROM AUTHOR]

Extensive research has focused on the loess deposits in southern England, aiming to unravel their stratigraphic and palaeoenvironmental significance. However, no systematic mineral magnetic study on these deposits has yet been undertaken. Here we address this by investigating the magnetic mineral composition and alignment of loess at two sites in southern England, Lowland Point (LP) on the Lizard Peninsula of Cornwall, and Pegwell Bay (PB) in eastern Kent on the Isle of Thanet. A set of rock magnetic analyses was conducted to understand mineral magnetism within the studied sections. In addition, the primary depositional origin of the magnetic fabrics as well as their overprinting caused by various possible post‐depositional processes were examined through anisotropy of magnetic susceptibility (AMS). The magnetic mineral composition is similar at both sites, derived from both sedimentary (aeolian) and post‐depositional processes. The AMS results show magnetic foliation that varies between the two sites, aligning with the bedding plane, indicating deposition from gravitational dust fall at the PB site, and a stronger wind transport energy at the LP site. Although the magnetic lineation of bulk AMS is relatively weak, there is a noticeable tendency towards alignment in most samples, with flow directions from the SE indicated at both sections if a strong wind is assumed at LP, although with a possible SW direction if a weaker wind is assumed. These observations may imply the preservation of palaeowind directions during dust transport, with a substantial southerly component, which contradicts previous assertions of dominant northerly or northeasterly winds. Indeed, a possible dominant southeasterly wind direction between 25 and 18 ka would suggest a limited influence of katabatic, westerly or polar northeasterly winds during dust transport, and rather may imply the effect of low‐pressure systems passing through the English Channel during that period. [ABSTRACT FROM AUTHOR]

We present the synthesis of two new novel tetradentate ligands based on 1,3,4-oxadiazole, 2-(2-pyridyl)-5-[N,N-bis(2-pyridylmethyl)aminomethyl]-1,3,4-oxadiazole (LTetraPy–ODA) and 2-(2-phenyl)-5-[N,N-bis(2-pyridylmethyl)aminomethyl]-1,3,4-oxadiazole (LTetraPh–ODA). The ligands were used to prepare six mononuclear complexes [FeII(LTetraPy–ODA)(NCE)] (C1–C3) and [FeII(LTetraPh–ODA)(NCE)] (C4–C6) where E = S, Se or BH3. In addition, the ligand LTetraPy–ODA was employed in the synthesis of a new di-nuclear complex [Fe II2 (LTetraPh)](ClO4)4·1 CH3NO2·1.5 H2O (C7). Characterization of all complexes was carried out using single-crystal X-ray crystallography, elemental analysis, and infrared spectroscopy. Magnetic susceptibility measurements, performed in the temperature range of 2–300 K using a SQUID magnetometer, revealed spin crossover behaviour exclusively in the mononuclear complexes C3 and C6, in which two monodentate NCBH3− co-ligands coordinate. The presence of the lattice solvent was found to be crucial to the spin transition property, with complex C3 exhibiting a switching temperature (T1/2) of approximately 165 K and C6 approximately 194 K. The other four mononuclear complexes C1, C2, C4, C5, as well as the dinuclear complex C7 are locked in the high spin state over the measured temperature range. Density Functional Theory (DFT) calculations were performed on complexes C1–C6 to rationalise the observed magnetic behaviour, demonstrating the significant effect of the NCS−, NCSe− and NCBH3− co-ligands ligands on the spin-crossover behaviour of the [FeII(L)(NCE)] complexes. [ABSTRACT FROM AUTHOR]

Spintronic devices that utilize spin transfer torque are promising for integrated memory applications. However, these devices face substantial energy consumption challenges due to the high current densities required for switching. Conversely, voltage‐driven spintronic devices, using capacitive displacement charge, can realize switching operations that are energy‐efficient (≈1–10 fJ bit−1). This work investigates switching based on voltage control of the interlayer exchange coupling in perpendicular magnetic anisotropy (PMA) multilayered heterostructures. Unlike previous works that utilized gating techniques that employ ionic transport mechanisms to control interlayer exchange coupling, this study employs electrostatic gating by using MgO, which is more compatible with modern spintronic‐based memories. These results suggest that the magnetization anisotropy, and the magnitude, and phase of the Ruderman‐Kittel‐Kasuya‐Yosida (RKKY) coupling function with spacer layer thickness can be controlled through electric gating, providing a promising avenue for the development of energy‐efficient magnetic data storage devices. [ABSTRACT FROM AUTHOR]

Localized magnetic moments in non-magnetic materials, by interacting with the itinerary electrons, can profoundly change the metallic properties, developing various correlated phenomena such as the Kondo effect, heavy fermion, and unconventional superconductivity. In most Kondo systems, the localized moments are introduced through magnetic impurities. However, the intrinsic magnetic properties of materials can also be modulated by the dimensionality. Here, we report the observation of Kondo effect in a heterodimensional superlattice VS2-VS, in which arrays of the one-dimensional (1D) VS chains are encapsulated by two-dimensional VS2 layers. In such a heterodimensional Kondo superlattice, we observe the typical Kondo effect but with intriguing anisotropic field dependence. This unique anisotropy is determined to originate from the magnetic anisotropy which has the root in the unique 1D chains in the structure, as corroborated by the first-principles calculation. Our results open up a novel avenue of studying exotic correlated physics in heterodimensional materials. The Kondo effect has been observed in transition metal dichalcogenides, where it typically stems from magnetic impurities. Here the authors report the Kondo effect in a heterodimensional superlattice VS2-VS, where dimensionality effects on intrinsic magnetic properties play a major role. [ABSTRACT FROM AUTHOR]

Direct current (DC) magnetometry data obtained for polycrystalline Mg3V4(PO4)6 were fitted by various magnetic models based on angular momentum basis states. As a result, single‐ion anisotropy of the magnetic V 3+ ions could be identified to decisively determine the magnetic properties of Mg3V4(PO4)6 and not antiferromagnetic exchange interaction between V ions as supposed in literature. It could be demonstrated analytically, by utilization of the Van Vleck equation, that also single‐ion anisotropy can lead to a linear and origin shifted inverse susceptibility curve in the high temperature region. The Weiss constant obtained from a Curie‐Weiss fit to such a susceptibility curve might falsely be ascribed to antiferromagnetic exchange interactions if additional low temperature magnetic properties are not considered for verification. [ABSTRACT FROM AUTHOR]

Two novel isostructural cyanide‐bridged hexadecanuclear complexes with the general formula {[Fe(CN)6]6[M{en(Bn)py}]10}2+ [M=Fe (12+), Ni (22+)] have been synthesized. The structural analyses disclose the presence of multivalent Fe centres with different spin states in complex 12+ whereas all the Fe centres share a conserved oxidation state in complex 22+. The DC magnetic study revealed antiferromagnetic interactions between the adjacent metal centres and ferrimagnetic behaviour in 12+. On the other hand, ferromagnetic interactions were observed in complex 22+ due to nearly orthogonal orientation of the interacting orbitals and poor spatial overlap as observed in BS‐DFT calculations. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) ferromagnets and their heterostructures offer fertile grounds for designing fascinating functionalities in ultra-thin spintronic devices. Here, by first-principles calculations, we report the discovery of energetically and thermodynamically stable 2D ferromagnets with very strong in-plane magnetic anisotropy in MnXY (X = S and Se; Y = Cl, Br, and I) monolayers. Remarkably, we find that the Curie temperatures of the ferromagnetic MnSBr, MnSI, MnSeCl, and MnSeI monolayers are as high as 271, 273, 231, and 418 K, respectively. In addition, we demonstrate that these ferromagnetic monolayers are intrinsic half-metals with large spin bandgaps ranging from 2.5 to 3.2 eV. When spin–orbit coupling is considered in these ferromagnetic monolayers, the nature of their half-metal is almost unaffected. Finally, the strong in-plane magnetic anisotropy of MnSY (Y = Br, I) and MnSeY (Y = Cl, I) monolayers originate mainly from halogen and chalcogen atoms, respectively. Our work shows that 2D Janus Mn-based ferromagnetic half-metals may have appealing functionalities in high-performance spintronic applications. [ABSTRACT FROM AUTHOR]

Direct current (DC) magnetometry data obtained for polycrystalline Mg3V4(PO4)6 were fitted by various magnetic models based on angular momentum basis states. As a result, single‐ion anisotropy of the magnetic V 3+ ions could be identified to decisively determine the magnetic properties of Mg3V4(PO4)6 and not antiferromagnetic exchange interaction between V ions as supposed in literature. It could be demonstrated analytically, by utilization of the Van Vleck equation, that also single‐ion anisotropy can lead to a linear and origin shifted inverse susceptibility curve in the high temperature region. The Weiss constant obtained from a Curie‐Weiss fit to such a susceptibility curve might falsely be ascribed to antiferromagnetic exchange interactions if additional low temperature magnetic properties are not considered for verification. [ABSTRACT FROM AUTHOR]

Complex oxides offer rich magnetic and electronic behavior intimately tied to the composition and arrangement of cations within the structure. Rare earth iron garnet films exhibit an anisotropy along the growth direction which has long been theorized to originate from the ordering of different cations on the same crystallographic site. Here, we directly demonstrate the three-dimensional ordering of rare earth ions in pulsed laser deposited (EuxTm1-x)3Fe5O12 garnet thin films using both atomically-resolved elemental mapping to visualize cation ordering and X-ray diffraction to detect the resulting order superlattice reflection. We quantify the resulting ordering-induced 'magnetotaxial' anisotropy as a function of Eu:Tm ratio using transport measurements, showing an overwhelmingly dominant contribution from magnetotaxial anisotropy that reaches 30 kJ m−3 for garnets with x = 0.5. Control of cation ordering on inequivalent sites provides a strategy to control matter on the atomic level and to engineer the magnetic properties of complex oxides. Magnetic anisotropy in mixed rare earth iron garnet films is shown to originate from the atomic ordering of the rare earth cations during growth of the film. Cation ordering on inequivalent sites provides a powerful strategy to engineer the magnetic properties of complex oxides. [ABSTRACT FROM AUTHOR]

In this article we analyze the thermal processes in magnetically anisotropic metal complexes under the action of non-adiabatic switching of magnetic field. Using the non-stationary perturbation theory for the case of sudden perturbation, we show that this field can cause not only heat release, but also heat absorption, interconnected with the axial zero field splitting (parameter D) in a paramagnetic metal complex. As an illustrative example we consider the simplest S = 1-complexes having "easy axis" and "easy plane" types of anisotropy influenced by the magnetic field that is suddenly turned off. We demonstrate that the character of the thermal processes (heat dissipation or absorption) depends on the sign of D and direction of applied field and so the analysis of these processes can be in principle used as a complementary tool (in addition to SQIUD magnetometry, EPR spectroscopy and INS) for studying magnetic anisotropy. The conditions under which the non-adiabatic switching of the magnetic field gives rise to the heat absorption are revealed. This unusual phenomenon, which can be called "nonadiabatic field switching cooling", may have practical applications. [ABSTRACT FROM AUTHOR]

Electric field control of magnetic properties offers a broad and promising toolbox for enabling ultra-low power electronics. A key challenge with high technological relevance is to master the interplay between the magnetic anisotropy of a ferromagnet and the exchange coupling to an adjacent antiferromagnet. Here, we demonstrate that magneto-ionic gating can be used to achieve a very stable out-of-plane (OOP) oriented magnetization with strong exchange bias in samples with as-deposited preferred in-plane (IP) magnetization. We show that the perpendicular interfacial anisotropy can be increased by more than a factor 2 in the stack Ta/Pt/PtMn/Co/HfO2 by applying −2.5 V gate voltage over 3 nm HfO2, causing a reorientation of the magnetization from IP to OOP with a strong OOP exchange bias of more than 50 mT. Comparing two thicknesses of PtMn, we identify a notable trade-off: while thicker PtMn yields a significantly larger exchange bias, it also results in a slower response to ionic liquid gating within the accessible gate voltage window. These results pave the way for post-deposition electrical tailoring of magnetic anisotropy and exchange bias in samples requiring significant exchange bias. [ABSTRACT FROM AUTHOR]

The recently proposed magnetoimpedance tomography method is based on the analysis of the frequency dependences of the impedance measured at different external magnetic fields. The method allows one to analyze the distribution of magnetic properties over the cross-section of the ferromagnetic conductor. Here, we describe the example of theoretical study of the magnetoimpedance effect in an amorphous microwire with inhomogeneous magnetic structure. In the framework of the proposed model, it is assumed that the microwire cross-section consists of several regions with different features of the effective anisotropy. The distribution of the electromagnetic fields and the microwire impedance are found by an analytical solution of Maxwell equations in the particular regions. The field and frequency dependences of the microwire impedance are analyzed taking into account the frequency dependence of the permeability values in the considered regions. Although the calculations are given for the case of amorphous microwires, the obtained results can be useful for the development of the magnetoimpedance tomography method adaptation for different types of ferromagnetic conductors. [ABSTRACT FROM AUTHOR]

This research looked at the effects of changing the doping level (x) on the characteristics of Ba0.8In0.2Fe12-xTbxO19 (x = 0.0 ≤ x ≤ 0.20) hexaferrites prepared using the sol–gel auto combustion procedure. X-ray diffraction analysis of the microstructure revealed that lattice parameters increased as the doping level (x) raised, while porosity and dislocations decreased. Williamson Hall plots showed that micro strains among particles decreased, and average grain size showed a negligible change, as shown by morphological analysis. As the doping level (x) raised, the saturation magnetization and remanence ratio decreased before increasing at higher temperatures above x = 0.15. Coercivity and magnetocrystalline anisotropy, on the other hand, both rose before decreasing. At x = 0.15, the saturation magnetization was 55.778 emu/g, the coercivity was 5.997 kOe, the anisotropic field was 1.87 kOe, and the average magnetic moment was 10.5 µB. The unique characteristics demonstrated by the synthesized material indicate its promise for the advancement of high-performance magnetic materials for use in a large range of applications, including recording media, magnetic filters, and other magnetic devices. [ABSTRACT FROM AUTHOR]

The structural, electronic, and magnetic properties of a novel two-dimensional monolayer material, TaF4, are investigated using first-principles calculations. The dynamical and thermal stabilities of two-dimensional monolayer TaF4 were confirmed using its phonon dispersion spectrum and molecular dynamics calculations. The band structure obtained via the high-accuracy HSE06 (Heyd–Scuseria–Ernzerhof 2006) functional theory revealed that monolayer two-dimensional TaF4 is an indirect bandgap semiconductor with a bandgap width of 2.58 eV. By extracting the exchange interaction intensities and magnetocrystalline anisotropy energy in a J1-J2-J3-K Heisenberg model, it was found that two-dimensional monolayer TaF4 possesses a Néel-type antiferromagnetic ground state and has a relatively high Néel temperature (208 K) and strong magnetocrystalline anisotropy energy (2.06 meV). These results are verified via the magnon spectrum. [ABSTRACT FROM AUTHOR]

(Fe,Co)2(P,Si) quaternary compounds combine large uniaxial magnetocrystalline anisotropy, significant saturation magnetization and tunable Curie temperature, making them attractive for permanent magnet applications. Single crystals or conventionally prepared bulk polycrystalline (Fe,Co)2(P,Si) samples do not, however, show a significant coercivity. Here, after a ball-milling stage of elemental precursors, we optimize the sintering temperature and duration during the solid-state synthesis of bulk Fe1.85Co0.1P0.8Si0.2 compounds so as to obtain coercivity in bulk samples. We pay special attention to shortening the heat treatment in order to limit grain growth. Powder X-ray diffraction experiments demonstrate that a sintering of a few minutes is sufficient to form the desired Fe2P-type hexagonal structure with limited secondary-phase content (~5 wt.%). Coercivity is achieved in bulk Fe1.85Co0.1P0.8Si0.2 quaternary compounds by shortening the heat treatment. Surprisingly, the largest coercivities are observed in the samples presenting large amounts of secondary-phase content (>5 wt.%). In addition to the shape of the virgin magnetization curve, this may indicate a dominant wall-pining coercivity mechanism. Despite a tenfold improvement of the coercive fields for bulk samples, the achieved performances remain modest (HC ≈ 0.6 kOe at room temperature). These results nonetheless establish a benchmark for future developments of (Fe,Co)2(P,Si) compounds as permanent magnets. [ABSTRACT FROM AUTHOR]

Mn5Ge3 is a ferromagnetic hexagonal crystal promising for spintronics and magnetocalorics. A systematic study and analysis of the magnetic properties of the Mn5Ge3 thin film grown on Si(111) were performed. The magnetic anisotropy of the film is determined by the shape anisotropy and the easy magnetization axis aligned along the c axis of the crystal. The uniaxial anisotropy constant Ku fully corresponds to that for a bulk single crystal, which indicates that c axis coincides with film normal. Mn5Ge3 film demonstrates high saturation magnetization MS = 900 emu/cm3 (900 kA/m) at T = 100 K and magnetocaloric effect ΔS = 3.16 ± 0.22 J kg−1 K−1 at 300 K and B = 1.5 T. ΔS is comparable to that for multicomponent or Gd rare earth films. Furthermore, a different anisotropy of the magnetocaloric effect compared to bulk Mn5Ge3 was found, which may be related to the anisotropy of the film shape and, possibly, to the domain structure. The results obtained are promising for the design and development of magnetocaloric, spintronic, and spin-caloritronic devices on a silicon platform. [ABSTRACT FROM AUTHOR]

The magnetization reversal kinetics has been theoretically considered for a nanosized ferromagnetic particle in a soft viscoelastic medium. In contrast to well-known works, we have considered the simultaneous action of the Néel mechanism of magnetization reversal of a particle (overcoming the potential barrier of magnetic anisotropy by its magnetic moment), and rotation (turn) of the particle body as a result of a change in the external magnetic field. The case of a high magnetic anisotropy of the particle is considered, i.e., it has been assumed that its energy significantly exceeds the thermal energy of the system and the energy of the interaction between the particle and the magnetic field. No other limitations have been imposed on field strength. The case of low fields has been considered in greater detail in the linear approximation of the dependence of magnetization on the field. The components of the complex susceptibility of the composite are calculated within the framework of this approximation. It has been shown that the real component of the susceptibility decreases monotonically with the field frequency. If the stiffness of the composite is high or low, the imaginary component has one maximum, which corresponds to the Néel mechanism of magnetization reversal or particle rotation in a viscoelastic medium, respectively. At intermediate values of composite stiffness, the frequency dependence of the imaginary susceptibility has two maxima. [ABSTRACT FROM AUTHOR]

Thermal heating process has been used, under a pressure of 10−7 mbar, to deposit thin films of cobalt onto monocrystalline silicon substrate. The incident beam strikes the substrates under normal incidence. The thickness ranges from 50 to 400 nm. To investigate the static magnetic properties, the hysteresis loops are performed by means of alternating gradient field magnetometer device. The zero-field magnetic structure has been investigated by magnetic force microscopy (MFM) technique, using a Veeco 3100 apparatus. MFM images reveal well-defined stripe patterns, mainly for the thickest films, which infer the dominance of the magnetocrystalline anisotropy. The easy magnetization axis lies within the plane of the film with a small component out-of-the plane for the thicker films. Coercivity evolution versus thickness follows a t−n Néel law, characteristic of Bloch domain wall motion. In addition, it was found that coercivity depends plainly on the surface roughness of the films. [ABSTRACT FROM AUTHOR]

The synthesis, structure and magnetothermal properties of three new lanthanide 1D polymeric complexes, {[Ln2Ba(α-fur)8(H2O)4]}n for Ln = Nd (1), Er (2) and {[Ho2Ba(α-fur)8(H2O)4]⋅2H2O}n (3), based on carboxylic α-fur = C4H3OCOO ligands is reported. The α-furoate ligands consolidate zigzag chains formed by Ln2 dimers separated by Ba ions. Ab initio calculations, in combination with the fit of experimental static magnetization and heat capacity, predict the magnetic ground state, energy levels and magnetic interactions in these heteronuclear nanomagnets. Nd2Ba (1) presents two different coordination sites for Nd, with an orthorhombic magnetic ground state. Nd ions are coupled along the chain through a weak antiferromagnetic (AF) interaction J″/kB = −0.08 K. Er(III) ions in Er2Ba (2) present a highly axial ground state, forming magnetic dimers with an interaction of J′/kB = −8.6 K, while interdimer coupling along the chain is J″/kB = −0.28 K. The Ho2Ba (3) complex consists of a highly anisotropic quasi-doublet with a ΔHo/kB = 0.7 K gap. Non-Kramers Ho ions form magnetic dimers within the Ho2Ba cluster, coupled by an AF intradimer interaction J′/kB = −2.5 K. The three complexes exhibit in-field slow relaxation of the magnetization: 1 relaxes through an Orbach process at high temperatures [Ueff/kB = 60(1) K] evolving to quantum tunneling below 3 K [τQT = 0.05(1) s]; 2 exhibits a rapid Orbach-like process [τ0 = 8(6)⋅10–8 s and Ueff/kB = 10(2) K] and 3 shows a direct process [τ = 0.4(1) s]. [ABSTRACT FROM AUTHOR]

Heat capacity measurements on the Ln = Gd case of the butterfly molecule series [Fe3Ln(μ3–O)2 (CCl3COO)8(H2O)(THF)3], in brief {Fe3LnO2}, are presented. In the previously studied {Fe3YO2} butterfly, where the magnetic properties stem only from the Fe3+ ions, magnetic chains of spin-5/2 Fe3Y clusters had been identified and described. The substitution of the nonmagnetic Y3+ ion by the magnetic Gd3+ adds magnetic interactions to the clusters, but not magnetic anisotropy. The heat capacity measurement shows an excess over the contribution of the antiferromagnetically coupled Fe3Gd magnetic clusters at very low temperature, which can be described as magnetic spin-1 chains using a Blume–Capel model. The intercluster interaction constant J ch = − 55 (5) mK is very similar to that of {Fe3YO2}, which shows that the interaction is mainly controlled by the magnitude of the cluster's magnetic moment. [ABSTRACT FROM AUTHOR]