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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]

The concept of building logically functional networks employing spintronics or magnetic heterostructures is becoming more and more popular today. Incorporating logical segments into a circuit needs physical bonds between the magnetic molecules or clusters involved. In this framework, we systematically study ultrafast laser-induced spin-manipulation scenarios on a closed system of three carbon chains to which three Ni atoms are attached. After the inclusion of spin–orbit coupling and an external magnetic field, different ultrafast spin dynamics scenarios involving spin-flip and long-distance spin-transfer processes are achieved by various appropriately well-tailored time-resolved laser pulses within subpicosecond timescales. We additionally study the various effects of an external magnetic field on spin-flip and spin-transfer processes. Moreover, we obtain spin-dynamics processes induced by a double laser pulse, rather than a single one. We suggest enhancing the spatial addressability of spin-flip and spin-transfer processes. The findings presented in this article will improve our knowledge of the magnetic properties of carbon-based magnetic molecular structures. They also support the relevant experimental realization of spin dynamics and their potential applications in future molecular spintronics devices. [ABSTRACT FROM AUTHOR]

Aperiodic order is ubiquitous in nature and quite relevant in science and technology. There are extensive works in aperiodic structures studying fundamental characteristics in physical properties, such as fractality, self-similarity, and fragmentation. However, there are fewer reports in which aperiodicity signifies an improvement in physical quantities with practical applications. Here, we show that the aperiodicity of fractal or self-similar type optimizes the tunneling magnetoresistance and spin-valley polarization of magnetic silicene structures, raising the prospects of spin-valleytronics. We reach this conclusion by studying the spin-valley-dependent transport properties of complex (Cantor-like) magnetic silicene structures within the lines of the transfer matrix method and the Landauer–Büttiker formalism. We find that the self-similar arrangement of magnetic barriers in conjunction with structural asymmetry reduces the conductance oscillations typical of periodic magnetic silicene superlattices and more importantly makes the K ′ -spin-down conductance component dominant, resulting in nearly perfect positive and negative spin-valley polarization states accessible by simply reversing the magnetization direction. The tunneling magnetoresistance is not as prominent as in periodic magnetic silicene superlattices; however, it is better than in single magnetic junctions. Furthermore, the optimization of the spin-valley-dependent transport properties caused by the complex structure is superior than the corresponding one reported in typical aperiodic structures, such as Fibonacci and Thue–Morse magnetic silicene superlattices. [ABSTRACT FROM AUTHOR]

Hybrid ferromagnet–semiconductor systems possess new outstanding properties, which emerge when bringing magnetic and semiconductor materials into contact. In such structures, the long-range magnetic proximity effect couples the spin systems of the ferromagnet and semiconductor on distances exceeding the carrier wave function overlap. The effect is due to the effective p–d exchange interaction of acceptor-bound holes in the quantum well with d-electrons of the ferromagnet. This indirect interaction is established via the phononic Stark effect mediated by the chiral phonons. Here, we demonstrate that the long-range magnetic proximity effect is universal and observed in hybrid structures with diverse magnetic components and potential barriers of various thicknesses and compositions. We study hybrid structures consisting of a semimetal (magnetite Fe3O4) or dielectric (spinel NiFe2O4) ferromagnet and a CdTe quantum well separated by a nonmagnetic (Cd,Mg)Te barrier. The proximity effect is manifested in the circular polarization of the photoluminescence corresponding to the recombination of photoexcited electrons with holes bound to shallow acceptors in the quantum well induced by magnetite or spinel itself, in contrast to interface ferromagnet in case of metal-based hybrid systems. A nontrivial dynamics of the proximity effect is observed in the studied structures due to recombination-induced dynamic polarization of electrons in the quantum well. It enables the determination of the exchange constant Δexch ≈ 70 μeV in a magnetite-based structure. The universal origin of the long-range exchange interaction along with the possibility of its electrical control offers prospects for the development of low-voltage spintronic devices compatible with existing solid-state electronics. [ABSTRACT FROM AUTHOR]

This work investigates the role of stable (sing-phased) and unstable (bi-phased) lattice structures in controlling the magnetic spin order and electronic properties in Co-rich ferrites of compositions Co1.25Fe1.75O4 and Co2.25Fe0.75O4. The material was synthesized via the chemical reaction of metal (Co and Fe) nitrates in an alkaline medium and post-heat treatment. The XRD patterns of Co1.25Fe1.75O4 showed a single-phased structure upon heat treatment in the temperature range of 200–900 °C, whereas Co2.25Fe0.75O4 showed a single-phased structure at 900 °C and bi-phased structure at a low heating temperature range of 200–800 °C. The thermally induced irreversibility (non-equilibrium) effect was observed in the lattice structure, magnetic spin order and electrical conductivity. The lattice structure at the (local) microscopic scale showed a more or less metastable state and coexistence of mixed-charge states of Co and Fe ions, irrespective of the single or bi-phased structure. The magnetic and electronic responses are found to be sensitive enough to detect local level non-equilibrium (metastable) states in non-equilibrium and equilibrium crystalline phases seen from XRD patterns. [ABSTRACT FROM AUTHOR]

We present the observational evidence of the existence of a double-decker filament channel (FC) by using observations in extreme ultraviolet and H α wavelengths. For both FCs, the east foot-point roots in the active region (AR), while the west one roots in the remote quiet region. The bottom FC (FC1) appears as intermittent filaments. Within the AR, the FC1 appears as an S-shaped filament (F1), which consisted of two J-shaped filaments (F1S/F1N for the south/north one). For the upper one (FC2), only the east part is filled with dark plasma and visible as a small filament (F2). Its east foot-point roots around the junction of F1S and F1N. Initially, due to the recurrent reconnections, F1N and F1S link to each other and form a new filament (F3) thread by thread. Meanwhile, the heated plasma, which appears as brightening features, flows from the east foot-point of F2 to the west, and becomes invisible about 1.1 × 105 km away. The failed eruption of F1S is triggered by the reconnection, which appears as the brightening threads changing their configuration from crossed to quasiparallel in between the F1S and F3, and is confined by the upper magnetic field. Associated with the eruption, the distant invisible plasma becomes visible as a brightening feature. It continuously flows to the remote foot-point, and becomes invisible before reaching it. The brightening plasma flow outlines the skeleton of FC2 gradually. The observations show the existence of a double-decker FC, as a magnetic structure, before they appear as a brightening/dark feature when fully filled with hot/cool plasma. [ABSTRACT FROM AUTHOR]

In one dimensional Ca 3 Co 2 O 6 , the magnetic frustration could result in partially disordered antiferromagnetic state. The Ca 3 Co 2 O 6 thus presents spin freezing and slow relaxation at low temperature. In this investigation, magnetic Cr3+-dopants were chosen to substitute the Co3+ cations and a series of Ca 3 Co 2- x Cr x O 6 ceramics were synthesized. Their magnetoelectric properties were characterized. The results manifest that the introduced Cr3+ cations situate in the CoO 6 octahedral centers and they could increase the lattice volume slightly. The antiferromagnetic coupling between Cr3+ and the adjacent Co3+ could reduce the frustration. The doped-Ca 3 Co 2- x Cr x O 6 compounds display a slower magnetic dynamic behavior. The Cr3+ substitution also has great impact on the dielectric properties of Ca 3 Co 2 O 6. The slower response of the freezing spin in Cr3+ doped-Ca 3 Co 2 O 6 makes the dielectric anomaly (anomaly Ⅰ) around the freezing temperature weakens with increasing Cr3+. Additionally, the introduced Cr3+ dopant not only increases the dielectric permittivity but also decreases the dielectric loss greatly. Cr3+ cation is a good candidate for improving the dielectric properties of Ca 3 Co 2 O 6. Magnetodielectric measurement reflects the effectiveness of magnetic field on manipulating the electric dipole of Ca 3 Co 2 O 6. For spin frustrated materials, electric measurement is proved to be an effective method on characterizing the subtle variation of the magnetic structure. [ABSTRACT FROM AUTHOR]

Recently, iron sulfide nanomaterials have drawn increased interest, due to their novel properties and extensive applications depending on their structure. To date, various methods have been employed for the synthesis of iron sulfide nanostructures with different shapes and morphologies. The synthesis method of iron sulfide nanomaterial is a challenge, as a small variation in sulfur content can lead to formation of different phases of iron sulfide. In this study, iron sulfide nanostructures were synthesized using our fast, simple, efficient, economical and environmentally friendly method in an electrochemical cell containing two iron sheets as electrodes in an aqueous solution of sodium sulfide. This method, with many advantages such as low-toxicity, low cost and easy handling, helps to control the properties of the products through the synthesis by tuning the growth conditions. Here, the influence of applied voltage ranging from 5 V to 25 V and annealing temperatures of 200 °C and 800 °C on the structure and magnetic properties of the products were studied. The samples were analyzed by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). XRD patterns confirmed the formation of monoclinic and hexagonal pyrrhotite at 200 °C and 800 °C, respectively. Based on SEM images, pyrrhotite in different shapes, such as quasi-spherical, feathers, sheets and flower-like structures, are formed depending on the applied voltage and annealing temperature. According to VSM results, all samples annealed at 200 °C are magnetically soft with only a little hysteresis, but the magnetization increases from 2.3 emu/g to 10.1 emu/g when applied voltage varies from 5 V to 25 V. All samples annealed at 800 °C exhibit an antiferromagnetic behavior. With increasing the applied voltage, the value of remanence magnetization and coercivity increases up to ∼2000 Oe and ∼0.14 emu/g, respectively. [ABSTRACT FROM AUTHOR]

Multiferroic composites of sol-gel synthesized Sodium Bismuth Titanate (Na 0.5 Bi 0.5 TiO 3) and Co–Ti substituted Barium Hexaferrite (BaFe 12-2x Co x Ti x O 19 ; x = 0.0, 0.5, 1.0, 1.5 and 2.0) in the ratio 3:1 was synthesized through ceramic route. Successful formation of R3c rhombohedral and P63 / mmc hexagonal phases corresponding to Na 0.5 Bi 0.5 TiO 3 and BaFe 12-2x Co x Ti x O 19 respectively was confirmed from the XRD and Rietveld refinement pattern. The frequency and temperature dependence of dielectric constant and loss of the composite systems exhibited typical dispersion behaviour which could be understood using the Maxwell-Wagner model. Substituted samples showed enhanced dielectric behaviour where dielectric constant was observed to increase while loss tangent decreased. Using the Universal Jonscher's Power law (JPL), conductivition mechanisms of the composite systems were studied from the ac conductivity behaviour which revealed that the x = 0.0 sample followed Non-overlapping Small Polaron Tunnelling (NSPT) model while the remaining samples followed the Correlated Barrier Hopping (CBH) model. The complex impedance and Nyquist plot analysis showed the enhancement of resistive property in the x ≠ 0 systems. Magnetic hysteresis loop measurements were conducted, and the associated parameters were determined with the assistance of the Law of Approach to Saturation (LAS). Favourable reduction in the magnetic anisotropy was observed indicating the disturbance of magnetic spin structure in the hexaferrite phase. The P-E loops established the novel room temperature multiferroic nature of the composite systems. Significant magnetoelectric coupling was detected at room temperature in all samples, with the x = 0.5 sample exhibiting the highest value of approximately 59.81 mV/cmOe. These desirable properties suggest that the composites may find future device applications as in magnetically tunable energy harvesting devices and self-powered magnetoelectric sensors in the future. [ABSTRACT FROM AUTHOR]

The exploration of the non‐collinear antiferromagnetic (AFM) phase holds promise for the discovery of zero thermal expansion (ZTE) materials, which is of great significance to resist the temperature effect in aerospace and precision engineering fields. Currently, there is still a lack of effective approaches to regulate this special AFM phase. In this work, a non‐collinear AFM phase has been obtained in the anti‐perovskite compound Mn3Fe0.2Co0.2Ni0.2Mn0.2Cu0.2N proposed by high‐entropy engineering. Utilizing neutron powder diffraction (NPD) analysis, the magnetic structure is resolved to be a triangular AFM phase with a k = [0, 0, 0] and a ferromagnetic (FM) component located at the corner of the cubic structure, which belongs to the R‐3 space group. Particularly, it presents ZTE behavior in a wide temperature range from 10 to 180 K. In‐situ NPD analysis reveals that the negative thermal expansion attributed to magnetic evolution almost offsets the normal positive thermal expansion quantified by the Debye formula. Further first principles calculations reveal that the specific AFM phase derives from the AFM‐type nearest neighboring magnetic exchange interactions and the easy‐axis‐type magnetic anisotropy. This demonstration offers an efficient strategy for designing magnetic structures and achieving ZTE over a wide temperature range. [ABSTRACT FROM AUTHOR]

Sr 1- x Ce x Fe 12 O 19 and Sr 1- x Ce x Fe 12- y O 19-δ (x = 0–0.2, y = 0–2) powders were synthesized by sol-gel auto-combustion method, and the effect on the structure and magnetic properties of changes in doping concentration and iron content has been investigated. XRD results confirmed the formation of M phase and impurities of CeO 2 and Fe 2 O 3. The SEM results show that cerium doping leads to a decrease in grain size. For Sr 1- x Ce x Fe 12 O 19 , the saturation magnetization increases to 77.73 emu/g first and then decreases with the increase of cerium doping. More importantly, our study also found that as the Ce doping concentration and iron content change, the interaction between the two changes differently. This interaction will have different effects on the occupancy of iron ions at spin-up and spin-down sites, ultimately leading to a significant characteristic change in magnetic properties. For Sr 1- x Ce x Fe 12- y O 19-δ , with the iron content decreases, the magnetic properties continue to decrease at x = 0.03, increase first and then decrease at x = 0.1, and keep improving at x = 0.2. It is of reference significance to change the magnetic properties of strontium ferrites by adjusting the relationship between rare earth doping concentration and iron content. [ABSTRACT FROM AUTHOR]

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Magnetic topological insulators exhibit unique electronic states due to the interplay between the electronic topology and the spin structure. The antiferromagnetic metal EuIn2As2 is a prominent candidate material in which exotic topological phases, including an axion insulating state, are theoretically predicted depending on the magnetic structure of the Eu2+ moments. Here, we report experimental results of the nuclear magnetic resonance (NMR) measurements of all the nuclei in EuIn2As2 to investigate the coupling between the magnetic moments in the Eu ions and the conduction electrons in In2As2 layers and the magnetic structure. The 75As and 115In NMR spectra observed at zero external magnetic fields reveal the appearance of internal fields of 4.9 and 3.6 T, respectively, at the lowest temperature, suggesting a strong coupling between the conduction electrons in the In2As2 layer and the ordered magnetic moments in the Eu ions. The 75As NMR spectra under in-plane external magnetic fields show broad distributions of the internal fields produced by an incommensurate fan-like spin structure which turns into a forced ferromagnetic state above 0.7 T. We propose a spin reorientation process that an incommensurate helical state at zero external magnetic field quickly changes into a fan state by applying a slight magnetic field. [ABSTRACT FROM AUTHOR]

Regional magnetic data in the southeastern segment of the Nigerian Niger Delta were evaluated with the aim of mapping deep-seated tectonic elements. Enhanced filtering operations and 3D forward modelling were applied on the magnetic data. These geologic features triggered the formation of rollover anticlines and faults that serve as structural traps in the study area. The filtered residual magnetic data revealed geologic structures characterized with NE -- SW, N -- S, and E -- W orientations. The 3-D models detected the faulted crustal blocks, gradient zones, and intra-basement compositional magnetic variations. Furthermore, some prominent horst and graben structures as well as related normal faults characterized with distinct magnetic signatures were observed. Faults of base magnetic (of various compositions) were observed to be the fabricating mechanisms of the magnetic anomalies. Collectively, these structures influenced the patterns of magnetic anomalies with direct effects on the hydrocarbon trapping systems, as well as the pathways and accumulation zones for hydrothermal minerals. On the whole, the interpreted results revealed that the basement surface is rippling. Additionally, the depth result showed sedimentary thicknesses that ranged from 4-10 km. Again, the estimated crustal thickness varied from 14 to 19 km. This study has displayed the capabilities of the magnetic method in mapping the depth and configuration of basement rocks, which are crucial in controlling the formation of structural traps. Identifying these basement structures early helps in understanding the overall geological framework and potential hydrocarbon systems. [ABSTRACT FROM AUTHOR]

The solution-processed methylammonium lead tri-iodine (MAPbI3), with long spin lifetimes and large spin diffusion lengths, has merit for developing stable perovskite spin valves (PeSV) with low saturation fields. By far, it remains challenging to avoid ill-defined ferromagnet-MAPbI3 interfaces during device fabrications using solution methods and to quantify the hybridized interfacial electronic and magnetic structures. Herein, an annealing-free method was developed for the fabrication of MAPbI3 based PeSV. In comparison to a thermally annealed device, an improved room temperature magnetoresistance (MR) was achieved. We found remarkable interfacial contributions to anisotropic magnetoresistance and MR. The first-principles calculation was further adopted to quantify the interfacial spin and orbital moments. Our results suggest that the orbital hybridization and the spin transfer are remarkable for the formation of the spin-dependent interfacial density of states. It consequently affects magnetic switching behaviors. This study holds an exceptionally important role for a deep understanding of the spin-polarized electronic transport through the Ni-MAPbI3 hybridized interface. [ABSTRACT FROM AUTHOR]

We present a new compound in the silver–cobalt-fluoride system, featuring paramagnetic silver (d9) and high-spin cobalt (d6), synthesized by solid-state method in an autoclave under F2 overpressure. Based on powder X-ray diffraction, we determined that AgIICoIIIF5 crystallizes in a monoclinic system with space group C2/c. The calculated fundamental band-gap falls in the visible range of the electromagnetic spectrum, and the compound has the character of charge-transfer insulator. AgCoF5 is likely a ferrimagnet with one predominant superexchange magnetic interaction constant between mixed spin cations (Ag–Co) of −62 meV (SCAN result). Magnetometric measurements conducted on a powdered sample allowed the identification of a transition at 128 K, which could indicate magnetic ordering. [ABSTRACT FROM AUTHOR]

2D magnetic materials with high spin polarization and Curie temperature are highly desirable for ultrathin spintronic devices. This study utilizes first‐principles methods to systematically investigate 225 O adsorption configurations, demonstrating that Cr2COx MXene consistently maintains a long‐range‐ordered ferromagnetic arrangement with high spin polarization, irrespective of the O adsorption configuration. Most configurations also display Curie temperature (TC) exceeding room temperature, with the possibility of further enhancement by reducing O coverage. Machine learning models are developed to accurately predict O adsorption configurations, exchange interaction energies, and TC. A novel approach of stripping F and OH groups to create Cr2COx on Cr‐based MXene surfaces is proposed to address the difficulty in achieving long‐range‐ordered magnetic structures by manipulating surface adsorbates in MXene. This approach enhances the ability to control the magnetic properties of MXenes and paves the way for their application in ultrathin spintronic 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]

In this study, Zn-Al ferrite/polypyrrole (PPy) nanocomposites were synthesized and thoroughly characterized to explore their potential for microwave applications. X-ray diffraction analysis confirmed the presence of ZnO, AlFeO3, and Fe2O3 phases, with the crystal size decreasing from 31 nm to 19.6 nm as aluminum content increased. High-resolution transmission electron microscopy (HR-TEM) revealed a distinctive core–shell morphology, where the polypyrrole encapsulates the ZnAlxFe2−xO4 particles. Magnetic measurements showed that decreasing aluminum concentration led to a reduction in both saturation magnetization (Ms) from 75 emu/g to 36 emu/g and remanent magnetization (Mr) from 2.26 emu/g to 2.00 emu/g. Dielectric analysis indicated that both the real (ε′) and imaginary (ε″) components of dielectric permittivity decreased with increasing frequency, particularly between 10 and 14 GHz. Furthermore, electrical modulus analysis highlighted the significant impact of aluminum doping on relaxation time (τIP), indicating the presence of interface polarization. Impedance spectroscopy results underscored the dominance of interface polarization at lower frequencies and the presence of strong conduction paths at higher frequencies. These combined magnetic and dielectric loss mechanisms suggest that the Zn-Al ferrite/polypyrrole nanocomposite is a promising candidate for advanced microwave absorption applications. [ABSTRACT FROM AUTHOR]

The arrival directions of ultrahigh-energy cosmic rays (UHECRs) observed above 4 × 1019 eV provide evidence of localized excesses that are key to identifying their sources. We leverage the 3D matter distribution from optical and infrared surveys as a density model of UHECR sources, which are considered to be transient. Agreement of the sky model with UHECR data imposes constraints on both the emission rate per unit matter and the time spread induced by encountered turbulent magnetic fields. Based on radio measurements of cosmic magnetism, we identify the Local Sheet as the magnetized structure responsible for the kiloyear duration of UHECR bursts for an observer on Earth and find that the turbulence amplitude must be within 0.5–20 nG for a coherence length of 10 kpc. At the same time, the burst-rate density must be above 50 Gpc−3 yr−1 for Local Sheet galaxies to reproduce the UHECR excesses and below 5000 Gpc−3 yr−1 (30,000 Gpc−3 yr−1) for the Milky Way (Local Group galaxies) not to outshine other galaxies. For the transient emissions of protons and nuclei to match the energy spectra of UHECRs, the kinetic energy of the outflows responsible for UHECR acceleration must be below 4 × 1054 erg and above 5 × 1050 erg (2 × 1049 erg) if we consider the Milky Way (or not). The only stellar-sized transients that satisfy both Hillas' and our criteria are long-duration gamma-ray bursts. [ABSTRACT FROM AUTHOR]

Adding trace Ni elements and annealing in a magnetic field improves the soft magnetic properties of the Finemet. After changing the Ni content to control the composition of the alloy system and change the pitch of stripes of the magnetic domains, Fe73.5Si14.7B7.6Nb3Cu1Ni0.2 nanocrystalline ribbon with excellent soft magnetic properties was obtained. In this work, transverse magnetic field annealing (TA) was performed on Fe73.5Si14.7B7.6Nb3Cu1Ni0.2 nanocrystalline ribbon cores (NRCs), and the magnetic properties and magnetic domain structure were compared in detail with those after non-field annealing (NA), and the mechanism of the improvement of soft magnetic properties by TA was elucidated. The soft magnetic properties of the cores were adjusted by varying the Ni composition, annealing temperature, and magnetizing temperature. The experimental results show that the core loss (Ps) of the NRCs is reduced by 24.76% (100 kHz, high frequency) and the coercivity (Hc) is 0.854 A/m after 30 min of TA at 400°C compared to the NA sample. TA optimizes the soft magnetic performance of NRCs by optimizing the domain structure and broadening the size of the domain. These results can provide a good guide for optimizing the performance of NRCs with low Ps at high frequency. [ABSTRACT FROM AUTHOR]

In recent years, it has been found that magnetic dip caused by diamagnetic motion of injected plasma can provide an appropriate environment for excitation of electromagnetic ion cyclotron (EMIC) waves. These findings have been widely reported in the Earth's magnetic environment. However, it has rarely been reported in Jupiter's magnetic environment. This paper reports the characteristics of EMIC waves observed by Juno in the magnetic dip of Jupiter. Multiple‐band EMIC waves are observed in frequency range from 10−3 Hz to several Hz. The theoretical analysis shows that in this event both He+ band and O+ band EMIC waves can be constrained in the magnetic dip, which is consistent with the wave emissions observed inside the magnetic dip. Our result provides the first evidence that EMIC wave can be ducted inside a magnetic dip in Jupiter's magnetosphere. Plain Language Summary: The relationship between magnetic structures and electromagnetic waves in the Earth's magnetosphere has been widely reported. Recent studies have theoretically displayed the effects of the magnetic dip on the EMIC wave propagation in Earth's magnetic field. In this paper, we use the event observed by Juno in the magnetic environment of Jupiter to analyze the effect of the magnetic dip on the propagation of EMIC waves. As a result, the observed EMIC waves can be ducted inside the magnetic dip of Jupiter's magnetosphere. Since these ducted waves would influence the dynamics of energetic protons through longtime scattering effects, the magnetic dip is expected to play an important role in the dynamics of Jupiter's magnetosphere. Key Points: Electromagnetic ion cyclotron (EMIC) waves are observed during the magnetic dip by JunoTheoretical analysis about the effects of magnetic dips on the EMIC wave propagation in Jupiter's magnetosphere is performedBoth He+ and O+ band EMIC waves can be ducted inside the magnetic dip in Jupiter's magnetosphere [ABSTRACT FROM AUTHOR]

Based on observations from the Magnetospheric Multiscale mission, this study presents an analysis of a short large‐amplitude magnetic structures (SLAMS) event with simultaneous occurrence of low‐ and high‐frequency magnetosonic whistler waves. It was found that low‐frequency magnetosonic whistler waves around the lower‐hybrid frequency emerge in the presence of solar wind ions and local low‐energy ions in the trailing region of SLAMS. Additionally, counter‐propagating whistler waves (the high‐frequency branch of the magnetosonic whistler wave) are observed within SLAMS, coinciding with a perpendicular temperature anisotropy in the electron population. Instability analyses demonstrate that these low‐frequency waves are induced by the two‐stream instability associated with the cross‐field relative velocity between low‐energy ions and electrons, while whistler waves are locally generated by the whistler anisotropy instability. Our results shed light on the impact of SLAMS on particle and wave dynamics in the terrestrial foreshock. Plain Language Summary: Short large‐amplitude magnetic structures (SLAMS) are frequently observed within the terrestrial foreshock. They play a significant role in particle dynamics, often leading to the formation of unstable ion and electron velocity distributions. Consequently, plasma waves are excited across both ion and electron scales. Despite their importance, direct observational evidence linking SLAMS to the local excitation of plasma waves has been lacking. In this study, we utilized observations from the Magnetospheric Multiscale mission to investigate the local excitation of magnetosonic whistler waves associated with SLAMS. We revealed the presence of counter‐propagating whistler waves within SLAMS. We attributed the generation of these waves to the local whistler anisotropy instability. Furthermore, we found the occurrence of low‐frequency magnetosonic whistler waves in the trailing region of SLAMS. We identified their excitation mechanism as the two‐stream instability relating to local low‐energy ions. These results offer valuable insights into the intricate interplay between SLAMS and particle‐wave dynamics within the terrestrial foreshock. Key Points: MMS observes both low‐ and high‐frequency magnetosonic whistler waves associated with SLAMS in Earth's foreshockCounter‐propagating high‐frequency magnetosonic whistler waves are proposed to be excited by the whistler anisotropy instability in SLAMSLow‐frequency magnetosonic whistler waves are excited by the cross‐field relative velocity between low‐energy reflected ions and electrons [ABSTRACT FROM AUTHOR]

Although chromium trihalides are widely regarded as a promising class of two-dimensional magnets for next-generation devices, an accurate description of their electronic structure and magnetic interactions has proven challenging to achieve. Here, we quantify electronic excitations and spin interactions in CrX3 (X = Cl, Br, I) using embedded many-body wavefunction calculations and fully generalized spin Hamiltonians. We find that the three trihalides feature comparable d-shell excitations, consisting of a high-spin 4A2 ( t 2 g 3 e g 0 ) ground state lying 1.5–1.7 eV below the first excited state 4T2 ( t 2 g 2 e g 1 ). CrCl3 exhibits a single-ion anisotropy Asia = − 0.02 meV, while the Cr spin-3/2 moments are ferromagnetically coupled through bilinear and biquadratic exchange interactions of J1 = − 0.97 meV and J2 = − 0.05 meV, respectively. The corresponding values for CrBr3 and CrI3 increase to Asia = −0.08 meV and Asia= − 0.12 meV for the single-ion anisotropy, J1 = −1.21 meV, J2 = −0.05 meV and J1 = −1.38 meV, J2 = −0.06 meV for the exchange couplings, respectively. We find that the overall magnetic anisotropy is defined by the interplay between Asia and Adip due to magnetic dipole–dipole interaction that favors in-plane orientation of magnetic moments in ferromagnetic monolayers and bulk layered magnets. The competition between the two contributions sets CrCl3 and CrI3 as the easy-plane (Asia + Adip >0) and easy-axis (Asia + Adip <0) ferromagnets, respectively. The differences between the magnets trace back to the atomic radii of the halogen ligands and the magnitude of spin–orbit coupling. Our findings are in excellent agreement with recent experiments, thus providing reference values for the fundamental interactions in chromium trihalides. [ABSTRACT FROM AUTHOR]

Spintronic devices are regarded as prime candidates for addressing the demands of emergent applications such as in-memory computing and the Internet of Things, characterized by requirements for high speed, low energy consumption, and elevated storage density. Among these, spin valves, serving as fundamental structures of magnetic random-access memory, have garnered substantial attention in recent years. This study introduces an all van der Waals (vdW) heterostructure composed of Fe3GeTe2 (FGT)/tellurene/FGT, wherein a thin layer of Weyl semiconductor Te is interposed between two ferromagnetic FGT layers. The proposed configuration exhibits a characteristic spin valve effect at temperatures below 160 K. This effect is attributed to spin-dependent transport and spin-dependent scattering phenomena occurring at the interfaces of the constituent materials. Furthermore, as temperature decreases, the magnetoresistance ratio (MR) of the device increases, indicative of the heightened polarization ratio of FGT, with an MR of 0.43% achievable as the temperature approaches 5 K. This investigation elucidates the underlying operational mechanisms of two-dimensional spin valve devices and lays the groundwork for the realization of spin-based integrated circuits. [ABSTRACT FROM AUTHOR]

2‐D modular wireless power transfer (WPT) system needs to have stable output when coil misalignment occurs. In order to improve the misalignment tolerance of the system coupling unit, this article proposes a magnetic coupling structure based on the LCC‐S compensation topology by combining a rectangular coil with two sets of mutually orthogonal solenoidal compensation coils. The rectangular coil is used to receive the vertical magnetic flux, and the two sets of compensating coils are used to receive the magnetic flux in the directions of X‐axis and Y‐axis on the horizontal plane, separately. The receiving side of the 2‐D wireless power transmission array cells cascaded half‐bridge rectifiers to connect each group of coils. This arrangement effectively compensates for the voltage drop of the rectangular coil caused by positional offset in any direction, so that the output voltage of the receiving side remains stable. The article firstly establishes the equivalent circuit model of the proposed design and deduces in detail the relationship equations between the output characteristics of the system and each influence factor. Secondly, the magnetic coupling structure is designed by finite element electromagnetic simulation software, and the total equivalent mutual inductance fluctuation of the proposed design is verified to be within 3.9% over the range of 2‐D transmission array cells. Finally, a 150 W experimental platform is built to verify the misaligment‐tolerant of the proposed design in the range of 2‐D transmission array cells. The experimental results show that the output voltage fluctuation of the proposed design within 4.27% at all directional offsets. Moreover, the stable output performance can be obtained in the case of vertical and rotational misalignment. [ABSTRACT FROM AUTHOR]

Spintronic devices are regarded as prime candidates for addressing the demands of emergent applications such as in-memory computing and the Internet of Things, characterized by requirements for high speed, low energy consumption, and elevated storage density. Among these, spin valves, serving as fundamental structures of magnetic random-access memory, have garnered substantial attention in recent years. This study introduces an all van der Waals (vdW) heterostructure composed of Fe3GeTe2 (FGT)/tellurene/FGT, wherein a thin layer of Weyl semiconductor Te is interposed between two ferromagnetic FGT layers. The proposed configuration exhibits a characteristic spin valve effect at temperatures below 160 K. This effect is attributed to spin-dependent transport and spin-dependent scattering phenomena occurring at the interfaces of the constituent materials. Furthermore, as temperature decreases, the magnetoresistance ratio (MR) of the device increases, indicative of the heightened polarization ratio of FGT, with an MR of 0.43% achievable as the temperature approaches 5 K. This investigation elucidates the underlying operational mechanisms of two-dimensional spin valve devices and lays the groundwork for the realization of spin-based integrated circuits. [ABSTRACT FROM AUTHOR]

Molecular-based magnetic materials are expected to serve as building blocks for quantum bits. To realize high-dimensional Hilbert space and addressability, we constructed anisotropic multi-level systems based on CuII and VIV with orthogonal magnetic orbitals. The crystal structures and intramolecular magnetic couplings of four CuIIVOII complexes [{CuVO(appen)2}2], [{CuVO(fhma)2EDA}2], [{CuVO(hfca)2EDA}2] and [CuVO(hfca)2DPEDA]n are characterized. Due to the orthogonal magnetic orbitals of CuII and VIV, the Cu–V pairs in the four complexes have strong ferromagnetic couplings, and the coupling strength is linearly related to the dihedral angle between the two equatorial planes of the two coordination polyhedra. Because of the triplet ground state, the system can be described by an effective Hamiltonian model consisting of two S = 1 spins coupled together. The anisotropy parameters of [{CuVO(hfca)2EDA}2] and [CuVO(hfca)2DPEDA]n were obtained by the simulation of X-band continuous wave electron paramagnetic resonance (cw-EPR) spectra, confirming that both complexes have zero-field splitting addressable on the relative energy scale. The results indicate that constructing multi-centre complexes based on orthogonal magnetic orbitals is a promising strategy for designing multidimensional quantum bits. [ABSTRACT FROM AUTHOR]

Juno conducted two close Io flybys on 30 December 2023 and 03 February 2024, both at a minimum altitude of 1,500 km. Filamentary structures in the electric and magnetic field spectra indicate Juno crossed the Alfvén wing, the magnetic structure connecting Io to Jupiter's polar ionosphere. We show that the first pass took Juno diametrically through the northern Alfvén wing, while the second pass had Juno graze the southern Alfvén wing boundary, enabling extended measurements of the transition region between Io's vicinity and the Jovian magnetosphere. Of note, evidence of local electron beams is inferred from whistler‐mode emissions. We demonstrate that their energies are sub‐keV, are sourced from Io's ionosphere or local torus, and are part of a distributed current system connecting Io to Jupiter. Finally, upper hybrid resonances indicate electron densities are significantly elevated in Io's polar region (∼28,000 cm−3) compared to the local Io torus (∼2,000 cm−3). Plain Language Summary: Juno conducted two close Io flybys. Signatures in the electromagnetic field indicate that Juno sampled the region dominated by the electrodynamic interaction between Io and Jupiter. Powerful electric currents flow within this region that deliver energetic electrons into Jupiter's polar atmosphere, resulting in the Io auroral footprint. Juno also spent an extended period along the boundary of this region, providing an in situ view of the complexity of this region's structure. Local density measurements indicate significantly elevated densities in Io's poles. Key Points: Juno plasma wave observations are consistent with Alfvén wing crossings during close Io flybysWhistler‐mode radiation indicate the presence of sub‐keV electron beams operating just outside the Alfvén wingElectron densities are significantly elevated in Io's polar region [ABSTRACT FROM AUTHOR]

In this study LiFePO4/C composite particles were synthesized using five different carbon sources via a one-step sol-gel method. La-doped LiFePO4 was also synthesized using the sol-gel method. The XRD pattern of LixLayFePO4 (x = 0.9~1.0, y = 0~0.1) after being calcined at 700 °C for 10 h indicates that as the doping ratio increased, the sample's cell volume first increased then decreased, reaching a maximum value of 293.36 Å3 (x = 0.94, y = 0.06). The XRD patterns of Li0.92La0.08FePO4 after being calcined at different temperatures for 10 h indicate that with increasing calcination temperature, the (311) diffraction peak drifted toward a smaller diffraction angle. Similarly, the XRD patterns of Li0.92La0.08FePO4 after being calcined at 700 °C for different durations indicate that with increasing calcination times, the (311) diffraction peak drifted toward a larger diffraction angle. The infrared spectrum pattern of LixLayFePO4 (x = 0.9~1.0, y = 0~0.1) after being calcined at 700 °C for 10 h shows absorption peaks corresponding to the vibrations of the Li–O bond and PO43- group. An SEM analysis of LixLayFePO4 (x = 1, y = 0; x = 0.96, y = 0.04; x = 0.92, y = 0.08) after being calcined at 700 °C for 10 h indicates that the particles were irregular in shape and of uniform size. The hysteresis loops of Li0.92La0.08FePO4 after being calcined at 600 °C, 700 °C, or 800 °C for 10 h indicate that with increasing calcination temperature, the Ms gradually increased, while the Mr and Hc decreased, with minimum values of 0.08 emu/g and 58.21 Oe, respectively. The Mössbauer spectra of LixLayFePO4 (x = 1, y = 0; x = 0.96, y = 0.04; x = 0.92, y = 0.08) after being calcined at 700 °C for 10 h indicate that all samples contained Doublet(1) and Doublet(2) peaks, dominated by Fe2+ compounds. The proportions of Fe2+ were 85.5% (x = 1, y = 0), 89.9% (x = 0.96, y = 0.04), and 96.0% (x = 0.92, y = 0.08). The maximum IS and QS of Doublet(1) for the three samples were 1.224 mm/s and 2.956 mm/s, respectively. [ABSTRACT FROM AUTHOR]

An alternative way of skyrmion quasi-particle detection is simulated at low voltage bias. The point contact (PC), attached to the strip with a Néel-type skyrmion, can detect it with a higher efficiency than a magnetic tunnel junction. The method is based on detecting the skyrmion via the ballistic magnetoresistance ratio (BRR). PC's resistance with skyrmion significantly differs from the one without it. BRR is estimated in the framework of the point contact model for two directions of spin-polarized current: perpendicular to the transport direction (case 1) and along one (case 2). Skyrmion's size is assumed to be around 3.6 nm in diameter—smaller, or comparable, to the mean free path of electrons, allowing it to utilize the ballistic transport approach. As a result, resistance values for the considered Néel type skyrmion within the related size are estimated as 157 Ω for case 1 and 452.2 Ω for case 2 with optimistic BRR 101.3% and 291.7%, respectively. BRR for case 2 is higher due to the spin-filtering effect. The method also has the potential to detect the skyrmion type, or other magnetic nano structures such as bimeron, domain wall (DW), etc. [ABSTRACT FROM AUTHOR]