Search

The temperature dependence of the structural and magnetic properties of wolframite-type FeWO4 was studied in situ by high-pressure neutron diffraction. Neutron diffraction measurements were performed with the XtremeD instrument at the Institut Laue-Langevin up to a maximum pressure of 8.7(4) GPa and a minimum temperature of 30.0(5) K. The diffraction data were analyzed via Rietveld refinements. We found that despite producing a contraction of 5% of the volume, the maximum pressure applied in this study does not modify the Shubnikov space group below magnetic order. However, the orientation of magnetic moments and the Néel temperature are slightly modified with the pressure, which is expected according to the preexistent understanding of magnetism in wolframites. We also determined a pressure–volume equation of state of FeWO4 at 300 K, which is compared with previous x-ray diffraction studies and density-functional theory calculations. [ABSTRACT FROM AUTHOR]

The magnetic performance of NdFeB permanent magnets rapidly decreases as their operation temperature increases. This limits the power output of electric motors as their internal temperature quickly increases with the power demand. This is particularly problematic for applications where high peak power is required for a short period of time, for example during automobile highway acceleration or during an airplane lift-off. With the advances in additive manufacturing, one can envision to fabricate more complex motor geometries and magnetic structures, without additional costs, allowing for enhanced functionalities such as better thermal management. In this context, this paper investigates the feasibility of using phase changing materials (PCMs) to mitigate the temperature rise in permanent magnets (PMs) fabricated by additive manufacturing. The potential of PCM and its relevance was validated by modeling the thermal response of an electric motor during a representative electric vehicle driving scenario. It was found that segmented magnets with embedded phase changing materials would allow to efficiently control temperature rise. To validate the simulation results, PM test pieces with and without embedded PCMs were fabricated using cold spray additive manufacturing and tested using a custom laser thermal cycling setup. [ABSTRACT FROM AUTHOR]

Magnetometers have received considerable attention in recent years. Magnetic components offer an alternative methodology to improve the sensitivity. Due to their exceedingly small structural dimensions, metasurfaces exhibit significant competitiveness in field modulation. A magnetic field concentration phenomenon of spheres at the nanoscale is presented in this paper. The sensitivity of a magnetometer is, therefore, improved through the enhanced static or quasistatic magnetic field by the nanosphere concentrator. Magnetic field redistribution due to the assistance of nanospheres is discussed in this paper using the finite element method. The numerical method is verified with classical analytical equations with a single sphere. The simulation results show that the magnetic field concentrates in the near field behind the nanosphere along the direction of the magnetic flux density. The radius, material or permeability exactly, and distribution are critical parameters to the concentration strength. The magnetic gain of a single nanosphere with typical positive permeability of the typical soft magnetic material reaches 3, and thus, the field along the magnetic flux direction concentrates. Furthermore, the amplification factor is more prominent with the nanosphere arrays compared to a single sphere with the same scale of size, and amplification improves with the sphere numbers and distributions in the array arrangement, which provides a novel approach for the designing of the magnetic flux concentrator being monolithically integrated with the magnetometer probe. Our simulation results provide a new degree of freedom by using nanoscale structures to manipulate magnetic fields. [ABSTRACT FROM AUTHOR]

The temperature dependence of the structural and magnetic properties of wolframite-type FeWO4 was studied in situ by high-pressure neutron diffraction. Neutron diffraction measurements were performed with the XtremeD instrument at the Institut Laue-Langevin up to a maximum pressure of 8.7(4) GPa and a minimum temperature of 30.0(5) K. The diffraction data were analyzed via Rietveld refinements. We found that despite producing a contraction of 5% of the volume, the maximum pressure applied in this study does not modify the Shubnikov space group below magnetic order. However, the orientation of magnetic moments and the Néel temperature are slightly modified with the pressure, which is expected according to the preexistent understanding of magnetism in wolframites. We also determined a pressure–volume equation of state of FeWO4 at 300 K, which is compared with previous x-ray diffraction studies and density-functional theory calculations. [ABSTRACT FROM AUTHOR]

This study investigates the effects of Zn substitution on the magnetic properties of ∼5 nm cobalt ferrite nanoparticles (ZnxCo1−xFe2O4, where x = 0, 0.13, 0.34, and 0.55), demonstrating that Zn substitution induces complex changes in spin canting and prompts a redistribution of cations among the sublattices. We reconstructed the magnetic structure of these spinel ferrites by integrating the classical two-sublattice Néel model of ferrimagnetism with the data obtained from 57Fe Mössbauer spectrometry. Consequently, this research provides a comprehensive understanding of how Zn substitution tunes the magnetic properties of CoFe2O4 nanoparticles, offering valuable insights into the development of magnetic materials with tailored properties for various applications. [ABSTRACT FROM AUTHOR]

To precisely investigate the electric properties and reveal the intrinsic interaction mechanisms between multiple fields in the composite magneto-electric-semiconductor shell structure, two-dimensional analyses were conducted within the framework of the third-order shear deformation theory and the coupled field theory. The governing equations for the composite piezoelectric semiconductor (PS) shell structures were derived using the principle of virtual work. Field distributions of the composite PS shell structures were obtained by expanding basic field quantities into Fourier series along the width direction and using the differential quadrature method. Prior to analysis, the convergence and correctness of the adopted method were evaluated. Several numerical examples were presented to demonstrate how magnetic manipulation can tune electrical behavior. It was found that inhomogeneous shear strain induced by applied magnetic fields is the key factor affecting potential variation in the composite PS shells. The appearance of potential barriers and wells in the composite PS shell structure with an opposite c axis is explained thoroughly. Additionally, the effect of magnetic field non-uniformity on the composite PS shell structure was investigated using an equivalent body force model, offering valuable insights for designing thin-film devices. [ABSTRACT FROM AUTHOR]

Two-dimensional spintronics has become a hot topic in recent years due to its advantages and potential in manipulating electron spins. In this paper, the electronic structures and magnetic properties of the Janus NbSSe monolayer are calculated using first-principles and Monte Carlo methods. Our study shows that the ground state of the material is a ferromagnetic metal. Under carrier doping, it undergoes a second-order phase transition from metal to half-metal, achieving 100% spin polarization, and enhancing or weakening ferromagnetic coupling. The value of the magnetocrystalline anisotropy energy is 570.96 μeV, and doping with an appropriate concentration of holes can transform the easy magnetization axis from in-plane to out-of-plane. Since the out-of-plane mirror symmetry is broken, we study the charge changes in the layer under the action of an external electric field. Due to the combined action of the external electric field and the built-in electric field, the layer exhibits a unique charge transfer mode. It is predicted that the Curie temperature of the material is about 156 K. When doped with 4.01 × 1013 cm−2 (0.04 holes per atom) concentration holes, the Curie temperature can reach about 350 K, indicating that the Curie temperature of the material can be reasonably controlled by regulating the carrier concentration. The coercive force calculated from the hysteresis loop is 0.01 T, and its hysteresis loss is low, showing its response to the external magnetic field. All of the above results indicate the application potential of this material in spin-electronic devices. [ABSTRACT FROM AUTHOR]

Magnetic gels with embedded micro-/nano-sized magnetic particles in cross-linked polymer networks can be actuated by external magnetic fields, with changes in their internal microscopic structures and macroscopic mechanical properties. We investigate the responses of such magnetic gels to an external magnetic field, by means of coarse-grained molecular dynamics simulations. We find that the dynamics of magnetic particles are determined by the interplay of magnetic dipole–dipole interactions, polymer elasticity, and thermal fluctuations. The corresponding microscopic structures formed by the magnetic particles, such as elongated chains, can be controlled by the external magnetic field. Furthermore, the magnetic gels can exhibit reinforced macroscopic mechanical properties, where the elastic modulus increases algebraically with the magnetic moments of the particles in the form of ∝ (m − m c ) 2 when magnetic chains are formed. This simulation work can not only serve as a tool for studying the microscopic and the macroscopic responses of the magnetic gels, but also facilitate future fabrications and practical controls of magnetic composites with desired physical properties. [ABSTRACT FROM AUTHOR]

Microwave (MW) transmission, absorption, and reflection loss spectra of the ferrimagnetic U-type hexaferrite Sr4CoZnFe36O60 ceramics were studied from 100 MHz to 35 GHz at temperatures between 10 and 390 K. Nine MW magnetic excitations with anomalous behavior near ferrimagnetic phase transitions were revealed. They also change under the application of the weak bias magnetic field (0–700 Oe) at room temperature. Six pure magnetic modes are assigned to dynamics of the magnetic domain walls and inhomogeneous magnetic structure of the ceramics, to the natural ferromagnetic resonance (FMR), and to the higher-frequency magnons. Three modes are considered the magnetodielectric ones with the dominating influence of the magnetic properties on their temperature and field dependences. The presence of the natural FMR in all ferrimagnetic phases proves the existence of the non-zero internal magnetization and magnetocrystalline anisotropy. Splitting of the FMR into two components without magnetic bias was observed in the collinear phase and is attributed to a change in the magnetocrystalline anisotropy during phase transition. The high-frequency FMR component critically slows down to phase transition. At room temperature, FMR splitting and essential suppression of the higher-frequency modes were revealed under the weak bias field (300–700 Oe). The highly nonlinear MW response and FMR splitting are caused by the gradual evolution of the polydomain magnetic structure to a monodomain one. The high number of magnetic excitations observed in the MW region confirms the suitability of using hexaferrite Sr4CoZnFe36O60 ceramics as MW absorbers, shielding materials and highly tunable filters. [ABSTRACT FROM AUTHOR]

The Mn3AgN-based manganese nitrides have attracted continuous attention due to the interesting functional properties, which is closely correlated with the magnetic evolution coupling with structural and electrical order. However, the attention on the fundamental magnetic behavior of the Mn3AgN matrix is still insufficient up to now. Here, the magnetic properties of Mn3AgN have been investigated by comprehensive magnetic measurements including dc magnetization, ac susceptibility, and magnetic relaxation. The results show that Mn3AgN undergoes two magnetic transitions with decreasing temperature: the transition from paramagnetic to antiferromagnetic (AFM) state at ∼285 K and from AFM to spin-glass-like (SGL) state at ∼110 K. The SGL state is essentially a mixed magnetic state of weak short-range ferromagnetic order and spin glass, and its appearance should be related to the AFM configuration of Γ4g with ferromagnetic component. The unique low-temperature magnetic structure of Mn3AgN makes it exhibit interesting low temperatures magnetic behavior, such as the magnetic irreversibility phenomenon, magnetic relaxation behavior, and so on. [ABSTRACT FROM AUTHOR]

Low-damping magnetic insulators like LiFe5O8 have gained considerable attention in recent years for their exceptional properties such as low energy loss and high gyromagnetic ratio, making them suitable in microwave and spintronic fields. However, due to factors such as crystalline quality and stress, the damping behavior of LiFe5O8 thin films falls below expectations. In this work, we utilize miscut substrate to modulate the structure and magnetic properties of LiFe5O8 films. We found that miscut angles can improve the crystalline quality of the film. However, a miscut angle of 6° resulted in a phase transition from tetragonal to orthorhombic in the LiFe5O8 phase. In particular, the out-of-plane ferromagnetic resonance linewidth of the orthorhombic LiFe5O8 (LFO) film was significantly reduced compared to that of the tetragonal LFO film on a non-miscut substrate, which could be attributed to the structural change. The orthorhombic LFO film also exhibited lower damping and a higher in-plane remanence ratio, indicating superior microwave magnetic properties. These findings suggest that miscut strain could be a viable method for improving the microwave magnetism of LFO films. [ABSTRACT FROM AUTHOR]

Magnetic structure factor (MSF), calculated from ground state configuration previously obtained by Monte Carlo simulation in different rectangular artificial spin ices, is employed to investigate ground state degeneracy. Our analysis considers the importance of nanoislands size to the ratio between rectangle sides in the lattice parameters via a dumbbell model. Pinch points in MSF along with residual entropy, determined for a number of different rectangular lattices with disconnected nanoislands, point out the conditions for the emergency of a gauge field, through which magnetic monopoles interact effectively. [ABSTRACT FROM AUTHOR]

Topological materials have shown promising potential in the spintronics application due to their conspicuous efficiency of charge-to-spin conversion. Our research investigates the temperature-dependent spin–orbit torque (SOT) from sputtered WTex. We reveal a strong temperature dependence of SOT and realize the current-induced SOT switching of WTex with perpendicular magnetic anisotropy structure under a wide range of 12 K to room temperature. Our findings reveal the temperature dependence of sputtered WTex and may pave the way for the spintronics application of semimetals under cryogenic temperature. [ABSTRACT FROM AUTHOR]

Topological materials have shown promising potential in the spintronics application due to their conspicuous efficiency of charge-to-spin conversion. Our research investigates the temperature-dependent spin–orbit torque (SOT) from sputtered WTex. We reveal a strong temperature dependence of SOT and realize the current-induced SOT switching of WTex with perpendicular magnetic anisotropy structure under a wide range of 12 K to room temperature. Our findings reveal the temperature dependence of sputtered WTex and may pave the way for the spintronics application of semimetals under cryogenic temperature. [ABSTRACT FROM AUTHOR]

Transition metal oxides (TMOs) demonstrate a broad spectrum of properties encompassing electronic correlations, anisotropic transport, magnetism, and optical behavior. The anisotropy arises from both intrinsic crystal symmetry and extrinsic factors like epitaxial strain and structural asymmetry at TMO interfaces. Weiss and Neel's work has elucidated anisotropic magnetic behavior in antiferromagnetic (AFM) materials. AFM TMOs exhibit unique magnetotransport behavior, including weak antilocalization (WAL) and anisotropic magnetoresistance (AMR). Understanding the magnetic structure and band topology in AFM perovskites and their interfaces enables the tailored design of materials for spintronics and energy conversion. In few interfaces lacking inversion symmetry, Rashba spin–orbit coupling (SOC) induces WAL, a quantum correction in conductivity in a two-dimensional electronic system. Electron accumulation and charge transfer across 3d, 5d transition metal-based perovskite interfaces affect WAL and AMR, as observed in 3d/3d and 3d/5d AFM heterostructures, respectively. Advancements in spintronics rely on exploring spin-dependent transport anisotropy. This review focuses on various scattering mechanisms, categorized as extrinsic and intrinsic, in anisotropic transport, particularly in 3d/5d AFM superlattices. The WAL scattering mechanism depends on both intrinsic factors related to Rashba SOC-induced band topology and extrinsic sources like spin impurities and lattice ions. Moreover, the investigation into AMR mechanisms involves the application of impurity-based extrinsic scattering models, which are aligned with the Rashba and Dresselhauss models on Fermi surfaces. This exploration specifically targets the interface of two-band insulators, exemplified by LaAlO3/SrTiO3 and LaVO3/KTaO3. Furthermore, this model achieves comprehensive coverage, extending its applicability to 3d/5d AFM heterostructures like LaMnO3/SrIrO3 and CaMnO3/CaIrO3. Additionally, the intrinsic scattering mechanism tied to Berry phase effects related to band topology is studied, focusing on the CaMnO3/CaIrO3 superlattice. Despite manipulation challenges stemming from reduced stray fields, AFM materials show potential in interface physics and applications within the realm of spintronics. [ABSTRACT FROM AUTHOR]

There exists a controversy in the literature concerning the values of coercive and bias fields in antidots magnetic structures formed by a hexagonal network of nanoholes. The coercive fields (H C) and the exchange bias fields (∣ H E X C ∣) for antidots (deposited on ultrathin anodic aluminum oxide, namely, AAO) are either increased or diminished by comparison with the same magnetic nanostructures grown on continuous substrates (namely, CML). We propose to elucidate these debates by showing the importance of the easy axis of the magnetization, the direction of the applied magnetic field, the thicknesses of the layers, and the 3D-topology of nanoholes, as well as the magnetic and thermal history of the magnetic measurements. Here, biased Ta(5 nm)/Pt(5 nm)/Co(0.6 nm)/Fe 50 Mn 50 (X)/Ta(5 nm) antidots are investigated by extraordinary Hall effect measurements at 5 K, where X varies in the (0–5.5) nm range. The substrate consists in a hexagonal array of holes, described by the pair of (p , d) values, respectively, the period as the distance from center to center of two consecutive holes and the hole diameter. The dimensions of antidots are (p ≈ 100 and d ≈ 40 nm) for X = (2–5.5) nm, (p ≈ 150 and d ≈ 60 nm) for X = 3.5 nm, and (p ≈ 100 and d ≈ 60 nm) for X = 0. A continuous stack using Si/SiO 2 (100 nm) is used for comparison. H C and ∣ H E X C ∣ gradually increase when X is enhanced for both substrates, with nevertheless a weak decrease at high X for the continuous system. Perpendicular magnetic anisotropy is only observed for both unbiased samples, the X = 2 nm continuous sample, and both X = 5 nm samples that have undergone field cooling treatment from 500 to 5 K under − 2 T. Usually, H C (AAO) > --> H C (CML), ∣ H E X C (AAO) ∣ > -->∣ H E X C (CML) ∣ , and ∣ H A (AAO) ∣ <∣ H A (CML) ∣ (H A designating the anisotropy field). However, for certain conditions, as, for instance, for FC-procedures starting from high temperatures and/or strong magnetic field, other situations might be observed. A discussion pertaining to the amplitudes of H C , ∣ H E X C ∣ and the anisotropy field (∣ H A ∣) of continuous and discontinuous samples is given for our experimental results as well as for published data in the literature, in the light of structural characteristics (wedge-to-wedge distance, porosity, or coverage ratio). Such biased perpendicular antidots might be particularly used in specific nanomaterials devoted to spintronics. [ABSTRACT FROM AUTHOR]

Antiferromagnetic spintronics is intrigued due to its unique properties that could break through the restrictions in ferromagnets. A 3d/5d transition metal oxide heterostructure is a good platform in antiferromagnetic spintronics research since the strong spin–orbit coupling in 5d oxides may bring about delicate interaction with the correlation energy and motivate unconventional phenomena. Here, the transport and magnetic characters of bilayers composed of antiferromagnetic 3d perovskite NdNiO3 and 5d perovskite SrIrO3 were investigated. The decreased metal–insulator transition and Néel temperature associated with suppressed negative magnetoresistance, emerged spin-glass like phenomenon, and the humped nonlinear Hall effect were observed in NdNiO3/SrIrO3 bilayers, which were absent in NdNiO3 and SrIrO3 pure films. It suggests the important role of interfacial interaction between NdNiO3 and SrIrO3 in modulating heterostructure transport and magnetic behavior and also manifests that complex magnetic structures might be realized in NdNiO3/SrIrO3 bilayers. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the properties of transition metal (TM)-doped α - G a 2 O 3 using first-principles calculations and Monte Carlo simulations. α - G a 2 O 3 is a wide-bandgap semiconductor material with enhanced performance and lower fabrication costs on sapphire substrates compared to β - G a 2 O 3 . Doping with TMs can modify electrical transport, optical absorption, and magnetic properties, yet theoretical studies on this are scarce. Our study focused on V, Cr, Mn, and Fe impurities. We introduced a newly proposed scheme for efficiently determining the ground-state defect configuration during structural relaxation. We adopt a recent, novel image charge correction method to accurately calculate formation enthalpy and thermodynamic transition levels for spin-polarized transition metal ion doping, without employing the empirical dielectric constant. Results showed Cr ions tend to neutral substitutional Ga, while V, Mn, and Fe impurity ions tend to carry a negative charge in common n-type α - G a 2 O 3 . Magnetic moments and spin-splitting impurity levels primarily arise from transition metal impurities and their d orbitals. We used the generalized four-state method to calculate exchange interaction constants between substitution lattice sites and identified (anti) ferromagnetic couplings at specific distances in a 120-atom supercell, which are negligible in total energy calculations. Monte Carlo simulations indicated a Curie temperature of 360 K in n-type α - G a 2 O 3 : Mn system with 12.5% doping, suggesting intrinsic ferromagnetic ordering based on the Heisenberg model. Our study contributes to understanding TM-doped α - G a 2 O 3 electronic structure and magnetic properties through improved methodologies. The approach can be applied in research involving other TM-doped oxides or wide-bandgap semiconductors. [ABSTRACT FROM AUTHOR]

In this paper, an ultra-thin absorber with a total thickness of 9.2 mm is designed and verified at the frequency band of 1–5.34 GHz. The absorber is composed of a layer of metasurface, multi-layered magnetic substrate, a layer of fragmented magnetic structure obtained by improved MOEA/D-GO (Multi-Objective Evolutionary Algorithm based on Decomposition combined with Enhanced Genetic Operators), and a copper back plate. The absorber is achieved by two steps. First, we designed and measured an ultra-thin absorber at 0.78–2.04 GHz by adding a layer metasurface onto the top of a basic multi-layer absorber composed of magnetic materials. The fractional bandwidth (FBW) of the absorber is 89.4%, and the electrical thickness is only 0.024 λ 0 at the lowest operating frequency. Second, to broaden the bandwidth, we use an improved MOEA/D-GO to optimize one magnetic layer of the absorber. The working frequency band of the optimized absorber is 1–5.34 GHz, covering L- (1–2 GHz), S- (2–4 GHz), and partial C-bands (4–8 GHz). Furthermore, we modified the structure of the metasurface to make the absorber polarization-independent. The FBW of the final absorber is 136.4%, and the electrical thickness is 0.031 λ 0 at the lowest operating frequency. The prototype of the absorber is measured, and the experimental results agree well with the simulated performance. The results show that the improved MOEA/D-GO can be used to design and optimize sophisticated electromagnetic (EM) structures with the predesigned properties, and the absorber with ultrathin thickness and light weight verified in this paper have great application potentials in EM compatibility, EM shielding, and radar cross section reduction at the low bands of the microwave spectrum. [ABSTRACT FROM AUTHOR]

Two-dimensional ferromagnetic materials hold great promise to develop energy-efficient magnetoelectric memory devices and next-generation spintronics. However, one of the crucial challenges for these materials is the realization of tunable magnetocrystalline anisotropy (MCA) to balance thermal stability and energy efficiency. Here, we systematically study the adsorption effects of 3d transition metals (3d-TMs) on the electronic structure and magnetic property of the Fe3GeTe2 (FGT) monolayer. The adsorption systems exhibit different ground state configurations depending on the adatoms, while the controlled perpendicular magnetic anisotropy has also been achieved. Notably, the Mn/FGT system can maintain the out-of-plane magnetic orientation with a changing amplitude of MCA energy up to 3.057 erg/cm2 as the external strain varies from −4% to 1%. In contrast, the Fe/FGT structure undergoes spin reorientation from in-plane to out-of-plan magnetization with a distinct modification behavior of MCA. We elucidate that the underlying atomistic mechanism mainly arises from the alteration of Fe-derived 3d-orbital states in response to the strain effect, leading to competitive changes in the different coupling states. These findings can not only provide useful guidance to optimize two-dimensional magnets for fundamental research but also reveal the promising potential of TMs/FGT materials for the development of ultra-low energy spintronic devices. [ABSTRACT FROM AUTHOR]

Ferrimagnetic antiperovskite Mn 4 N has received growing interest due to room-temperature observation of large perpendicular magnetic anisotropy, low saturation magnetization, and ultrafast response to external magnetic fields. Comprehensive understanding of the underlying magnetic structure is instrumental in design and fabrication of computer memory and logic devices. Magneto-optical spectroscopy provides deeper insight into the magnetic and electronic structure than magnetometry. Simulations of a magneto-optical Kerr effect in biaxially strained Mn 4 N are performed using density functional theory and linear response theory. We consider three ferrimagnetic phases, two collinear and one noncollinear, which have been investigated separately by earlier studies. The simulated spectra are compared to measured magneto-optical data available in recent literature. One of the collinear ferrimagnetic phases is found to be consistent with the measured spectra. We show that an admixture of the noncollinear phase, which is the ground state of unstrained Mn 4 N, further improves the agreement with measured spectra, and at the same time, it could explain the lower than predicted net moment and magnetic anisotropy observed in thin films on various substrates. [ABSTRACT FROM AUTHOR]

H−T phase diagrams for chromium oxide chloride (CrOCl) are usually obtained using data from the measurements of magnetization and specific heats. Recent works suggest that magnetic anisotropy exists in CrOCl. In this work, we use dynamic cantilever magnetometry, which is sensitive to both magnetization and magnetic anisotropy, to probe phase transitions in CrOCl flakes. Together with magnetization measurements from a Superconducting Quantum Interference Device, four major regions of the CrOCl H−T phase diagram along its c-axis are obtained, which is consistent with the previously reported works. Then, we studied magnetic field induced transitions in CrOCl flakes under four different temperatures. Several transitions in antiferromagnetic state and in incommensurate state, which have not been reported before, were recognized. We believe these transitions probably originate from magnetic anisotropy due to magnetoelastic coupling and lattice reconstruction in CrOCl. Our work provides intriguing experimental results on the intricate magnetic structure of CrOCl, making progress in understanding the rich magnetic states of CrOCl. [ABSTRACT FROM AUTHOR]

L10-MnAl exhibits excellent magnetic properties and could be used as a candidate to fill the gap between hard ferrite and rare-earth based permanent magnet (PM) applications. However, one of the major problems with L10-MnAl is that the structure is metastable and decomposes to other structural phases at higher temperature. Therefore, enhancing the structure stability of L10-MnAl is essential for PM applications. We studied the prospect of improving the structural stability and increasing the uniaxial magnetic anisotropy energy (K u) of the L10-MnAl structure in this work. It is found that C-doping at the 1d interstitial site enhanced the structure stability of the compound. Moreover, Fe substitution on Mn sites shows a significant increase in the uniaxial magnetic anisotropy energy (K u). Therefore, the electronic structure and magnetic properties of L10-ordered Mn1−xFexAlC (x = 0, 0.125, 0.250, 0.375, 0.50, 0.625, 0.75, and 0.87) alloys are investigated by using the first-principles calculations. The results show that x = 0.375 Fe content in the L10-MnAl alloy and 6% doping of C maintained the structural stability and provided a maximum value of K u = 2.13 (MJ/m3), which is 25% higher than for the pristine L10-MnAl, making it suitable for permanent magnet applications. [ABSTRACT FROM AUTHOR]

The nuclear and magnetic structures of CaxSr2−xWMnO6 (x = 0.5, 1.0, 1.5) have been investigated by neutron diffraction at 295, 30 or 40 K, and 4 or 5 K. The compounds crystallized in the monoclinic symmetry with a space group P21/n. The nuclear structure consists of ordered WO6 and Mn2+O6 octahedral frameworks, with lattice constant a decreasing more rapidly than b with increasing Ca content. No structural change was found around the magnetic transition temperature, although the Mn octahedron below the magnetic order temperature exhibited a slightly compressed Jahn–Teller distortion (0.1–0.3 Å) along the c axis. A standard magnetic model was used to solve the magnetic structure, with the Mn magnetic moments ferromagnetically coupled along the a axis and anti-ferromagnetically coupled along the b and c axes, resulting in a magnetic propagation vector of k = (0,1/2, 1/2) and a magnetic superlattice of 1a × 2b × 2c. In each crystallographic cell, the Mn1–Mn2 atoms are antiferromagnetically configurated, compensating the total moment to zero by symmetry. A layer-type magnetism along the (111) crystallographic plane was confirmed to couple antiferromagnetically between these planes and ferromagnetically within them. The magnetic structure refinement confirmed an average Mn moment of 4.5 μB. Also, it reveals that the collinear magnetic Mn configuration has three possible spin orientations, namely, (with their standard deviation) [μx = (3.3 ± 0.4) μB, μy = (2.5 ± 0.3) μB, μz = (−0.7 ± 0.7) μB], [μx = (3.0 ± 0.4) μB, μy = (0.5 ± 0.2) μB, μz = (−2.8 ± 0.2) μB, and [μx = (−1.8 ± 0.4) μB, μy = (2.9 ± 0.2) μB, μz = (−2.4 ± 0.3) μB. The first configuration is estimated to be the ground state, while the other magnetic configurations are an optimum local value derived from the refinements. Combined with the density functional theory calculations, these experimental results confirm a high-spin state Mn2+ (d5) electron configuration. [ABSTRACT FROM AUTHOR]

We report the detailed analysis of temperature dependent neutron diffraction pattern of the Cr 2 CoAl inverse Heusler alloy and unveil the magnetic structure up to the phase transition as well as its fully compensated ferrimagnetic nature. The Rietveld refinement of the diffraction pattern using the space group I 4 ¯ m2 confirms the inverse tetragonal structure over the large temperature range from 100 to 900 K. The refinement of the magnetic phase considering the wave vector k = (0, 0, 0) reveals the ferrimagnetic nature of the sample below 730 ± 5 K. This transition temperature is obtained from empirical power law fitting of the variation in the ordered net magnetic moment variation in intensity of (110) peak as a function of temperature. The spin configuration of the microscopic magnetic structure suggests the nearly fully compensated ferrimagnetic behavior where the magnetic moments of Cr2 are antiparallel with respect to the Cr1 and Co moments. Moreover, the observed anomaly in the thermal expansion and lattice parameters at 730 ± 5 K suggests that the distortion in the crystal structure may play an important role in the magnetic phase transition. [ABSTRACT FROM AUTHOR]

In this study, Fe 80 Ce 20 films were deposited on Si(100) and glass substrates using sputtering in a high-vacuum environment and subsequently heat-treated in a vacuum annealing furnace. The films, with thicknesses ranging from 10 nm to 50 nm, were annealed at temperatures of 100 °C, 200 °C, and 300 °C. The objective was to investigate the effects of film thickness and annealing temperature on the structural, surface energy, and magnetic properties of the material. X-ray diffraction (XRD) analysis confirmed the crystalline nature of both Si(100)/Fe 80 Ce 20 and Glass/Fe 80 Ce 20 films. Atomic force microscopy (AFM) revealed a smooth film surface that became rougher after annealing. Contact angle measurements indicated hydrophilic properties, with the highest surface energy observed in the as-deposited films due to a higher density of defects and grain boundaries. The hysteresis loop demonstrated exceptional soft magnetic properties and a high saturation magnetization (Ms) of approximately 2000 emu/cm³. Annealing at 100 °C altered the magnetic domain structure from a striped labyrinthine configuration to an aligned pattern. At higher annealing temperatures, the films exhibited grain growth, increased surface roughness, and new grain formation. Following annealing, the grains in the Fe 80 Ce 20 films became larger, surface roughness increased, and the water contact angle increased, rendering the films more hydrophobic. The as-deposited films displayed the highest surface energy due to the high density of defects and grain boundaries. Increased surface roughness led to more grain boundary defects and irregularities, which served as pinning points for magnetic domain walls, thus increasing coercivity (Hc). Rough surfaces induced local stress fields, increased magnetic anisotropy, and decreased saturation magnetization. Thermal perturbations from higher annealing temperatures further disrupted the alignment of the magnetic moments, leading to a reduction in saturation magnetization. [ABSTRACT FROM AUTHOR]

The physicochemical properties of NZFO/f-MWCNTs composites based on 5 wt% of Ni 0.5 Zn 0.5 Fe 2 O 4 (NZFO) nanoparticles and functionalized multi-walled carbon nanotubes (f-MWCNTs) synthesized via ex-situ method are presented. The influence of annealing on the as-received hybrids is discussed. The structural and microstructural analysis confirms the efficiency of the synthesis process. The slight redistribution of cations over tetrahedral and octahedral sites is noted by Raman and X-ray photoemission (XPS) studies. The NZFO crystallite size is almost stable over sample processing, but the presence of single particles, clusters and aggregates on the f-MWCNTs' surface is proven. The XPS spectra comparison reveals the domination of nanotubes as designed. The deconvoluted Fe2 p lines confirm the iron redistribution slightly modified by annealing. The magnetic properties analysis revealed the cluster-glass state of NZFO particles. The core-shell-like structure with a magnetic core and disordered layer is evidenced. The influence of Fe-based carbon matrix residues in all hybrids was detected. [ABSTRACT FROM AUTHOR]

Multiple-component materials with advanced microstructure are increasingly utilized in the development of microwave absorption materials. In this paper, a magnetic hollow sphere composed of Fe 3 O 4 @PS was fabricated by simply depositing Fe 3 O 4 nanoparticles onto the surface-modified PS hollow spheres through electrostatic interactions. The microwave absorption properties of Fe 3 O 4 @PS hollow spheres were studied by varying the loading capacity of Fe 3 O 4. The results show that when the Fe 3 O 4 content is 28.59 wt%, the optimal minimum reflection loss is −26.9 dB with effective absorption bandwidths (RL ≤ −10 dB) exceeding 0.3 GHz. Furthermore, the straightforward combination of the Fe 3 O 4 @PS with MWCNTs enables the enhancement of the microwave absorption up to −41.4 dB at 14.5 GHz, with an effective absorption bandwidth exceeding 5.9 GHz (12.1–18 GHz) at a thickness of 2 mm. This study is expected to provide valuable insights into the design of nanocomposites for microwave absorption applications. [ABSTRACT FROM AUTHOR]

High-entropy perovskite ceramics (HEPCs) with equal atomic ratios have recently emerged as a highly promising class of materials due to their unique magnetic properties. However, the crystal structure, microstructure and magnetic properties of unequal atomic ratios HEPCs have yet to be fully investigated. In this paper, single-phase HEPCs (La 0.25 Nd 0.25 Sm 0.25 Gd 0.25) 1- x Ho x MnO 3 ((LNSG) 1- x H x MO) have been synthesized using solid-state reactions. The effect of Ho element content (x = 0.25, 0.3, 0.35 and 0.4) on the structure and magnetic properties was systematically investigated. All samples exhibit an orthorhombic perovskite structure with a Pbnm space group and show obvious crystallization characteristics after sintering at 1250 °C for 16 h (LNSG) 1- x H x MO HEPCs display a smooth surface texture and distinct grain boundaries, as well as significant hysteresis effects at T = 5 K. The spin-orbit interaction and magnetic anisotropy between Ho and Mn ions increase with the increase of Ho content, which increases the saturation magnetization (M s) of HEPCs. (LNSG) 0.6 H 0.4 MO exhibits the lowest magnetic hysteresis losses among the considered samples, attributed to its highest M s (50.95 emu/g) and the lowest coercivity H c (0.6 kOe). These characteristics endow it with a potential application in magnetic storage devices. [ABSTRACT FROM AUTHOR]

Advancements and utilization of magnetic refrigeration technology hinge on the ongoing enhancement and optimization of magnetic refrigeration material properties. Nevertheless, the intricacy of the magnetocaloric effect (MCE) mechanism has emerged as a bottleneck, constraining the progress and refinement of magnetic refrigeration materials. In this study, a classic magnetic system is chosen to investigate the mechanism of MCE across four different scales–macroscopic magnetism, micrometer‐scale magnetic domains, atomic magnetic moments, and electronic structure. It simultaneously exhibits two inverse MCEs and one direct MCE, with a working temperature span as wide as 125 K (most are <50 K) for the direct MCE. The measurements of the vibrating sample magnetometer, in situ Lorentz electron microscopy and variable‐temperature neutron powder diffraction directly reveal that the complex magnetic entropy changes arise from the magnetic domain wall pinning, the instability of Ho magnetic moments, and the spin rotation. First‐principles calculations elucidate the crucial role of strong hybridization between localized Ho and itinerant Co electrons in the spin reorientation of HoCo4Al. This study contributes significantly to comprehending the induction mechanism of the MCE and holds vital reference value for exploring new magnetic refrigeration materials and enhancing MCE performance. [ABSTRACT FROM AUTHOR]

Pyrochlore oxides, specifically G d 2 Z r 2 O 7 , have been a subject of interest due to their unique structural, physical, and magnetic properties. These properties make pyrochlore oxides potential candidates for various technological applications, including magnetocaloric refrigeration. Magnetocaloric refrigeration is a promising alternative to conventional refrigeration methods, as it is more energy-efficient and environmentally friendly. By studying the magnetocaloric effect of pyrochlore oxides like G d 2 Z r 2 O 7 , researchers can gain a deeper understanding of the underlying mechanisms and potential applications of these materials in magnetocaloric refrigeration systems. By employing advanced computational methods such as Monte Carlo simulations and first-principles calculations based on the full-potential linearized augmented plane wave (FP-LAPW) a technique is employed to examine the magnetic structure, researchers can investigate the magnetocaloric effect of pyrochlore oxides with high accuracy and precision. This information has the potential to aid in the advancement of more effective magnetocaloric systems materials and ultimately lead to the design and optimization of advanced magnetocaloric refrigeration systems. [ABSTRACT FROM AUTHOR]

The magnetization processes and magnetocaloric effect (MCE) of molecular magnets are studied using the quantum Heisenberg model with the goal of finding magnetic structures with optimal magnetocaloric properties. To fulfill this goal, we examine the influence of various factors such as quantum fluctuations, the magnitude and distribution of spins, the cluster size and its geometry on the conventional (cooling) and inverse (heating) MCE. We find, surprisingly, that the best cooling and heating effects are observed in the Ising limit on the smallest possible molecular clusters represented by dimers and trimers. The increasing Heisenberg interaction suppresses both the cooling as well as heating effects, but while the heating is reduced very strongly, for relatively small values of the anisotropic Heisenberg constant, the cooling effects are reduced only weakly. Since the heating effect is undesired in low-temperature refrigeration, the Heisenberg limit is also interesting from a practical point of view. Moreover, we find that spin distributions also have a significant influence on the magnetocaloric properties of molecular magnets. Specifically, configurations with large spins on the edges of the finite chain significantly enhance the cooling effect. [ABSTRACT FROM AUTHOR]

The atomic structures, electronic structures, magnetic properties, and spin states of BiCoO3 multiferroic material under hydrostatic pressure are comprehensively investigated by using first‐principles calculation based on density functional theory. Firstly, we found the pressure‐tuned structural symmetry transition from tetragonal P4 mm (No. 99) to cubic Pm3¯$\bar{3}$m (No. 221) space group. The structural transformation prompts the Co─O polyhedral coordination transfer from a CoO5 pyramidal to a CoO6 distorted octahedron. Secondly, the pressure‐induced magnetic change from C‐type antiferromagnetic state to ferromagnetic state and then to paramagnetic configuration occurred after continuous compression of the volume. Essentially, the fundamental reason for the transition of the magnetic structure lies in the change of the internal atomic structure, such as the pressure induced abrupt changes of Co─O bond length and bond angle. Meanwhile, an obvious volume collapse was observed when the pressure was applied to 51–56 GPa. Finally, as the pressure increases, the magnetism changes from C‐type antiferromagnetic state to paramagnetic configuration, accompanying the transformation from high spin state with b2g2eg2a1g1b1g1 configuration in pyramid structure to low spin state with t2g6eg0 in octahedral field. Therefore, our results demonstrate that applied hydrostatic pressure in BiCoO3 can trigger the transformation of structure, magnetism, charge, and spin state. [ABSTRACT FROM AUTHOR]

The intercalation of magnetic atoms into van der Waals (vdW) gaps offers a versatile approach for manipulating local magnetic ordering in vdW magnets. However, these intercalated magnetic atoms are often intricately positioned within the gaps, resulting in an ambiguous impact on local magnetic interactions and spin configurations. Herein, the atomic and magnetic structures of self‐intercalated prototype materials Cr1+δTe2 are comprehensively investigated using transmission electron microscopy, elucidating the correlation between the concentration and distribution of intercalated Cr atoms and the evolution of spin textures. The observed transitions from topological Néel‐type skyrmions to non‐topological type‐II bubbles, and ultimately to trivial ferromagnetic domains, underscore the complex nature of these magnetic spin textures. The complexity of the local structural arrangements is further revealed through integrating atomic‐resolution imaging, revealing the disorder‐order‐disorder transitions manifested by the distribution of intercalated atoms. The modulation of intercalated atomic structure shapes the observed spin textures by affecting the Dzyaloshinskii−Moriya interaction (DMI), inter/intra‐layer coupling, and magnetic anisotropy. These findings provide profound insights into the structure‐magnetism relationship, offering promising avenues for engineering the magnetic properties of vdW magnets at the atomic level. [ABSTRACT FROM AUTHOR]

Magnetic holes (MHs) are transient magnetic structures responsible for energy conversion in space plasma. Using single-spacecraft measurements from Mars Atmosphere and Volatile EvolutioN (MAVEN), the existence of MHs on Mars has been confirmed. However, due to the limitations of single-spacecraft observations, significant uncertainty also arises on the identification of the spatial scale and 3D geometry of MHs. In this study, we report a series of MHs successively detected by Tianwen-1 near the high-latitude magnetopause and by the MAVEN spacecraft near the subsolar magnetopause. The large separation between Tianwen-1 and MAVEN (∼4 R M) suggests these MHs are macroscale structures extending along the axial direction. Additionally, we observe whistler waves generated by electron perpendicular anisotropy in one of the macroscale MHs. This study is the first joint observation of Martian MHs, shedding light on the research of transient magnetic structures on Mars. [ABSTRACT FROM AUTHOR]

Interface engineering is a promising strategy for controlling the Curie temperature (Tc) and perpendicular magnetic anisotropy (PMA) in magnetic 2D van der Waals (2D vdWs)‐based heterostructures. However, establishing high‐quality interface structures in magnetic 2D vdWs/metal stacks, crucial for maximizing interface effects, remains a significant challenge. Here, a Fe5‐xGeTe2/Pt (F5GT/Pt) prototype with a superior interface quality is achieved using a low‐power physical vapor deposition technique. The magnetic properties of the F5GT/Pt heterostructures are strongly influenced by employing the specific physical deposition method. Stable ferromagnetism at 400 K is observed when depositing Pt atoms with relatively high energy, despite the Tc of pristine F5GT being below 300 K. This unexpected high‐temperature ferromagnetism is attributed to the formation of a ferromagnetic alloy at the interface, commonly present in vdWs‐based stacks fabricated through physical deposition but often overlooked. The deposit of Pt atoms with ultralow energy leads to the formation of a unique Fe5‐xGeTe2/Fe3‐xGeTe2 heterojunction at the interface, significantly enhancing the PMA. This work emphasizes the importance of interface structures in vdWs‐based devices, suggesting that controlling the growth process offers an effective approach to construct and engineer vdWs heterostructures, thus improving the performance and introducing new functionalities to spintronic devices. [ABSTRACT FROM AUTHOR]

The structure and magnetic properties of epitaxial Heusler alloy films (Co2FeGe) deposited on MgO (100) substrates were investigated. Films of 60 nm thickness were prepared by magnetron co-sputtering at different substrate temperatures (TS), and those deposited at room temperature were later annealed at various temperatures (Ta). X-ray diffraction confirmed (001) [110] Co2FeGe || (001) [100] MgO epitaxial growth. A slight tetragonal distortion of the film cubic structure was found in all samples due to the tensile stress induced by the mismatch of the lattice parameters between Co2FeGe and the substrate. Improved quality of epitaxy and the formation of an atomically ordered L21 structure were observed for films processed at elevated temperatures. The values of magnetization increased with increasing TS and Ta. Ferromagnetic resonance (FMR) studies revealed 45° in-plane rotation of the easy anisotropy axis direction depending on the degree of the tetragonal distortion. The film annealed at Ta = 573 K possesses the minimal FMR linewidth and magnetic damping, while both these parameters increase for another TS and Ta. Overall, this study underscores the crucial role of thermal treatment in optimizing the magnetic properties of Co2FeGe films for potential spintronic and magnonic applications. [ABSTRACT FROM AUTHOR]

The magnetic toroidal dipole moment, which is induced by a vortex-type spin texture, manifests itself in parity-breaking physical phenomena, such as a linear magnetoelectric effect and nonreciprocal transport. We elucidate that a staggered alignment of the magnetic toroidal dipole can give rise to spontaneous magnetization even under antiferromagnetic structures. We demonstrate the emergence of uniform magnetization by considering the collinear antiferromagnetic structure with the staggered magnetic toroidal dipole moment on a bilayer zigzag chain. Based on the model calculations, we show that the interplay between the collinear antiferromagnetic mean field and relativistic spin-orbit coupling plays an important role in inducing the magnetization. [ABSTRACT FROM AUTHOR]

Current-induced field-free magnetic switching using spin–orbit torque has been an important topic for decades due to both academic and industrial interest. Most research has focused on introducing symmetry breakers, such as geometrical and compositional variation, pinned layers, and symmetry-broken crystal structures, which add complexity to the magnetic structure and fabrication process. We designed a relatively simple magnetic structure, composed of a [Co/Pt] multilayer and a Co layer with perpendicular and in-plane magnetic anisotropy, respectively, with a Cu layer between them. Current-induced deterministic magnetic switching was observed in this magnetic system. The system is advantageous due to its easy control of the parameters to achieve the optimal condition for magnetic switching. The balance between magnetic anisotropic strength and interlayer coupling strength is found to provide the optimal condition. This simple design and easy adjustability open various possibilities for magnetic structures in spin-based electronics applications using spin–orbit torque. [ABSTRACT FROM AUTHOR]

We investigate spin-polarized electronic structures of CoX2 (X = S, Se, and Te) monolayers using the density functional theory. We find that CoS2 and CoSe2 monolayers are metallic ferromagnetic materials, whereas CoTe2 monolayer is nonmagnetic metallic material. The 3D bulk layered crystalline structures of CoX2 (X = S, Se, and Te) are found to be nonmagnetic metals in our calculations. In addition to the major contributions due to the d orbitals of Co atoms, there is also contribution from the p orbitals of chalcogen X atoms to the electronic structure near the Fermi level of CoX2. We are optimistic for the experimental growth and uses of these monolayer structures for the 2D spintronic applications. [ABSTRACT FROM AUTHOR]

Summary: Omnidirectional Wireless Power Transfer (OWPT) system can provide power to multiple loads in space. The different loads have different requirements for current and power levels under various operating conditions. This paper proposes a Variable Receiving Coil (VRC) structure and its control strategy. Active regulation of the output current is achieved by adjusting the geometric size of the receiving coil. Meets the power supply needs of equipment in different scenarios. This design allows the effective value of the VRC current to remain stable within the range of 1.01–1.62A (transmission distance of 22–27 cm). By adjusting the geometric transformation state of the VRC, different output currents can be obtained under fixed positions, loads, and input voltages. The designed receiver can meet the differential current requirements of multiple spatial loads, and is insensitive to factors such as load, transmission distance, and rotation angle. This system can reduce the design complexity of charging and power supply systems and effectively promote the application of Wireless Power Transfer (WPT) in the field of Internet of Things devices. [ABSTRACT FROM AUTHOR]

The tailward high‐speed flows, in which various kinetic processes and magnetic structures can be embedded, are usually produced by the magnetic reconnection in the Earth's magnetotail. Here, using high‐resolution measurements from the Magnetospheric Multiscale (MMS) mission, we report an intense current in the tailward high‐speed flow. The current density can reach ∼180 nA/m2 and is primarily carried by electrons. Taking advantage of the First‐Order Taylor Expansion (FOTE) method, we reveal that such an intense current is associated with a ribbon‐like magnetic structure. A large electric field, reaching ∼90 mV/m, is also observed at the magnetic structure. The Hall term dominates the electric field, however, the contribution from the pressure gradient term and the electron inertial term is nonnegligible and can lead to strong energy conversion (E ⋅ J > 2 nW/m3) through the synergistic action with the intense current. This study improves the understanding of the current behaviors and energy conversion associated with magnetic structures in the Earth's magnetotail. Plain Language Summary: As products of the magnetotail magnetic reconnection, the earthward and tailward high‐speed flows can be usually observed as associated with a variety of kinetic processes and magnetic structures. Here, for the first time, we report an electron‐carried intense current associated with a ribbon‐like magnetic structure in the tailward high‐speed flow, by using high‐resolution MMS data and the First‐Order Taylor Expansion (FOTE) method. Encountering a large electric field with a nonnegligible contribution from the pressure gradient term and electron inertial term, such intense current leads to a strong energy conversion at the ribbon‐like magnetic structure. This study shed light on how the intense current is associated with the ribbon‐like magnetic structure and how the strong energy conversion is driven at such a structure, which complements the knowledge of the energy conversion process in the Earth's magnetotail. Key Points: An electron‐carried intense current (J > 180 nA/m2) is observed in association with a ribbon‐like structure in the tailward high‐speed flowA large electric field, with nonnegligible contribution from pressure gradient and electron inertial term, is observed at such a structureThe intense current and large electric field work together to drive a strong energy conversion (E ⋅ J > 2 nW/m3) at this structure [ABSTRACT FROM AUTHOR]

New cobalt(II)‐based complexes with [N2O2] coordination formed by two bis‐chelate ligands were synthesized and characterized by a multi‐technique approach. The complexes possess an easy‐axis anisotropy (D<0) and magnetic measurements show a field‐induced slow relaxation of magnetization. The spin‐reversal barriers, i. e., the splitting of the two lowest Kramers doublets (UZFS), have been measured by THz‐EPR spectroscopy, which allows to distinguish the two crystallographically independent species present in one of the complexes. Based on these experimental UZFS energies together with those for related complexes reported in literature, it was possible to establish magneto‐structural correlations. UZFS linearly depends on the elongation parameter ϵT of the (pseudo‐)tetrahedral coordination, which is given by the ratio between the average obtuse and acute angles at the cobalt(II) ion, while UZFS was found to be virtually independent of the twist angle of the chelate planes. With increasing deviation from the orthogonality of the latter, the rhombicity (|E/D|) increases. [ABSTRACT FROM AUTHOR]

2D materials, particularly 2D semiconductors, and layered antiferromagnetic (AFM) compounds, exhibit rich light‐matter coupling phenomena in low‐dimensional systems. In this work, the occurrence of interlayer exciton–magnon coupling (EMC) is observed in Néel‐type AFM of MnPX3 (X = S or Se) and monolayer (1L) WS2 heterostructures. The energy of neutral exciton in 1L WS2 can be tuned by the adjacent AFM order, resulting in an additional energy shift of 10–14 meV. Furthermore, by filtering the photoluminescence spectrum with graphene and conducting magnetic measurements, the correlation is elucidated between the interlayer EMC and AFM transition process. In MnPS3, this coupling behavior exhibits sensitivity to the changes of magnetic structures, manifesting with a correlated length ξ of 8.34 Å at temperatures higher than Néel temperature (TN). The decoupling process in WS2/MnPS3 heterostructure below 50 K is originated from a weak out‐of‐plane ferromagnetic order, confirming the presence of an XY‐type magnetic phase transition in MnPS3 at sub‐TN temperature. This study provides a fundamental understanding of EMC and its potential applications in the integration of optical and magnetic devices. [ABSTRACT FROM AUTHOR]

Two binuclear Gadolinium(III) (Gd) complex [Gd2(L1)2(H2L3)2(NO3)2] (1) and [Gd2(L2)2(H2L3)2(NO3)2] (2) were obtained by using 2‐hydroxybenzaldehyde or 2‐hydroxy‐1‐naphthaldehyde, 2‐aminophenol, pyridin‐2‐ylmethanamine and Gd(NO3)3 ⋅ 6H2O in CH3CN (H2L1=(E)‐2‐((2‐hydroxybenzylidene)amino)phenol, H2L2=(E)‐1‐(((2‐hydroxyphenyl)imino)methyl)naphthalen‐2‐ol, H2L3=pyridin‐2‐ylmethanamine). Structural analysis suggests that all the ligands as protective units protect the central Gd(III) ions at the periphery. Magnetization studies exhibited magnetocaloric effect of 14.45 J ⋅ kg−1 ⋅ K−1 at 4 K under ΔH=7 T for complex 1 and 12.69 J ⋅ kg−1 ⋅ K−1 at 2 K under ΔH=7 T for complex 2. In complexes 1 and 2, although the coordination configurations are the same, the significant difference in MCE may be due to the adjustments of the peripheral ligands leading to changes in the coordination field strength. The electron affinity of the ligands can impact the interaction between the ligands and Gd(III) ions. [ABSTRACT FROM AUTHOR]

Three novel polymeric Mn(II) acetate derivatives, identified as {[Mn2.5(OH)(CH3COO)4] ⋅ 0.5CH3OH ⋅ 0.5CH3CN}n (1), {[Mn3(CH3CO O)6] ⋅ 0.5CH3CN}n (2) and {Mn1.5K(CH3COO)4}n (3), have been successfully prepared by systematically adjusting the ratio of reactants and using the 2‐mercapto‐5‐methyl‐1,3,4‐thiadiazole (Hmmt) as the template agent. These three complexes can be regarded as the different crystalline forms of Mn(CH3COO)2 under different reaction conditions. Single‐crystal X‐ray diffraction analyses revealed that 1 and 2 feature the unique three‐dimensional (3D) framework. For 3, it displays a 2D structure, which is further assembled to form a 3D extended network via the weak hydrogen bond interactions. Magnetic studies confirmed that 1 and 2 show antiferromagnetic interactions, and 1 displays a long‐range ordering phase below the critical temperature (Tc) of 7.8 K. In addition, magnetisation data collected for 1–2 yield low magnetic entropy changes, which can be attributed to the strong antiferromagnetic interactions among the Mn(II) centres. [ABSTRACT FROM AUTHOR]

Topologically nontrivial magnetic structures such as skyrmion lattices are well known in materials lacking lattice inversion symmetry, where antisymmetric exchange interactions are allowed. Only recently, topological multi-q magnetic textures that spontaneously break the chiral symmetry, for example, three-dimensional hedgehog lattices, were discovered in centrosymmetric compounds, where they are instead driven by frustrated interactions. Here we show that the bilayer perovskite Sr3Fe2O7, previously believed to adopt a simple single-q spin-helical order, hosts two distinct types of multi-q spin textures. Its ground state represents a novel multi-q spin texture with unequally intense spin modulations at the two ordering vectors. This is followed in temperature by a new "spin meta-cholesteric" phase, in which the chiral symmetry is spontaneously broken along one of the crystal directions, but the weaker orthogonal modulation melts, giving rise to intense short-range dynamical fluctuations. Shortly before the transition to the paramagnetic state, vortex-crystal order spanned by two equivalent q vectors emerges. This renders Sr3Fe2O7 an ideal material to study transitions among multiple-q spin textures in a centrosymmetric host. [ABSTRACT FROM AUTHOR]

Based on the first‐principles calculation of density‐functional theory, the electronic structure and magnetic properties of hexagonal boron phosphide (h‐BP) with doping and applying strain to the transition‐metal (TM = Cr, Mn, Fe, Co, and Ni) elements are investigated. After the TM elements are introduced, the magnetism is induced. The magnetic moments are 3.00, 3.87, 1.00, 1.99, and 1.00 μB, respectively, which mainly contributed by the 3d orbitals of TM elements. In the case of magnetic coupling, Cr–Cr are mainly coupled antiferromagnetically at different distances. In addition, Fe–Fe performs a ferromagnetic state, and Co–Co represents an antiferromagnetic state with the distance of 3.213 Å. After applied strain, Co doped of the system shows the characteristics of semimetals under the application of 4% strain. It can be added that for h‐BP systems, doping Co and Mn increases its conductivity, which is beneficial to the study of spintronic materials. [ABSTRACT FROM AUTHOR]

Currently, solenoids are extensively utilized in various research fields due to their flexibility of fabrication and high magnetic field strength. However, the internal magnetic field of the solenoid itself exhibits some non-uniformity defects, which limits its application in some domains. This article proposes a novel single winding tightly wound solenoid structure with an improved magnetic field uniformity. To optimize the magnetic field near the aperture of the conventional solenoid, an auxiliary solenoid with a gradually changing diameter is included at each end of the solenoid. By adjusting different parameters of the auxiliary solenoid, the edge effect of the solenoid was reduced, and its overall magnetic field uniformity was improved. The optimization of the auxiliary solenoids is achieved through GA-KAN network techniques. Finite element simulation results with the optimized parameters show that the proportion of uniform areas can be improved by more than five times. The research results are a reference for high-precision electromagnetic sensing applications based on solenoids. [ABSTRACT FROM AUTHOR]

Magnetic skyrmions and skyrmioniums have garnered significant attention due to their distinctive topologically nontrivial spin structures. Gaining a deep understanding of the magnetization dynamics of these structures and their interconversion processes is essential for fully leveraging their potential in magnetic storage technology. Here, the dynamics of strain-controlled generation and annihilation of skyrmions and skyrmioniums are investigated using phase field simulation methods. It is discovered that tensile strain can induce the transformation of a single domain into skyrmions and skyrmioniums, which can still exist stably after the strain is released. Notably, skyrmioniums demonstrate robust stability within a specific strain window of −0.2% to 0.5%. Beyond this, escalating the compressive strain magnitude induces a phase transition from skyrmioniums to skyrmions, culminating in a direct collapse to a single-domain state at a critical compressive strain of −0.8%. This study reveals that strain can effectively control a variety of topological magnetic domain structures and achieve their interconversion, providing guidance for the design of low-power, nonvolatile, multi-state spin storage devices. [ABSTRACT FROM AUTHOR]