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We report a study on the interfacial antiferromagnetic coupling between ferrimagnetic TbIG/YIG thin films. TbIG/YIG bilayers are grown on YAG (110) substrates. The crystal structure and magnetic properties of the films are characterized. The temperature and directional dependences of the antiferromagnetic coupling effect are observed at low temperatures. This work enriches the magnetic research of ferrimagnetic oxide films with complex structures, providing new ideas for the design of antiferromagnetically coupled spintronics devices. [ABSTRACT FROM AUTHOR]

Direct epitaxial integration of magnetic layers with wide bandgap nitride semiconductors will enable spin-controlled transport and photonic phenomena, seeding ideas for functional spintronic devices. Using plasma-assisted molecular beam epitaxy (MBE) in a previously unexplored window, significantly improved ferrimagnetic Mn4N layers are successfully grown on GaN with ~1 nm surface roughness. Distinct from earlier reports, the Mn4N layers grown on GaN are found to be [001] oriented with 12-fold in-plane symmetry in the diffraction pattern. This unique epitaxial registry originates from three equivalent rotational domains. The ferrimagnetic magnetotransport properties of low growth temperature Mn4N layers on GaN are comparable to those reported on cubic substrates such as MgO. However, a sign-flip of the Hall resistance is discovered for Mn4N layers grown above 300 °C. [ABSTRACT FROM AUTHOR]

Polycrystalline GdFe1âˆ' x Ni x O3 (x  = 0.00, 0.02, 0.04) samples was synthesised using a glycine assisted solâ€"gel method to investigate the enhanced magnetic and electric properties of Ni substituted GdFeO3 systems. TG-DSC analysis of prepared samples confirms that GdFe1âˆ' x Ni x O3 have good thermal stability in high temperatures. The system has been stabilized in an orthorhombic structure with space group Pbnm. The elemental composition of GdFe1âˆ' x Ni x O3 has been estimated from EDAX spectrum. The results showed oxygen deficiency on increasing the Ni substitution and it has been supported by Rietveld refinement. FE-SEM images and Brunauerâ€"Emmettâ€"Teller analysis reveals that GdFe1âˆ' x Ni x O3 is a highly porous material and its porosity and specific area increases with Ni substitution. Magnetic measurements indicates that the system exhibited ferrimagnetic behaviour at low temperatures and canted antiferromagnetic behaviour at room temperature. For x  = 0.04 Ni content, magnetization reversal for applied field of 25 Oe has been observed. Increased coercivity of GdFeO3 with Ni substitution has been attributed to the grain size effect. From electrical point of view, dielectric permittivity of GdFeO3 has been enhanced with Ni substitution. This enhancement has been attributed to the cumulative effects of hopping of Fe2+â€"Fe3+ ions, grainâ€"grain boundary contribution, and space charge polarization. The role of grainâ€"grain boundary contribution is evident from electric modulus spectrum. The space charge effect has been realized in both impedance spectrum and dielectric loss. Temperature-dependent dielectric studies were conducted to understand the mechanisms and various aspects that contribute to the dielectric enhancement. A highly lossy capacitive nature in the P â€" E loop also suggests space charge effects due to Ni substitution in Fe sites. Availability of free charge carrier concentration is correlated with the optical properties of GdFe1âˆ' x Ni x O3. The decrease of optical band gap (2.5â€"2.21 eV) on increasing Ni content suggests the increasing electronic contribution in the system. [ABSTRACT FROM AUTHOR]

Mn4N is a typical transition metal nitride with antiperovskite structure. Mn4N films and Mn4N based heterostructures have attracted much attention for potential applications due to their ferrimagnetism, high thermal stability, perpendicular magnetic anisotropy and low saturation magnetization. The fascinating physical properties promise a series of novel applications in next-generation electronic, memory and energy-efficient devices. In this review, the progress of Mn4N films and its heterostructures are systematically summarized and discussed. In the 1st part, the various Mnâ€"N compounds with different phases are introduced, and the basic properties of manganese nitrides are emphasized in details, especially for the properties, superiorities and applications in spintronics of Mn4N. The 2nd part summarizes the fabrication methods, structure and physical properties of Mn4N films. Besides, the underlying mechanisms of Mn4N films and other similar materials are briefly reviewed. In the 3rd part, the tunable magnetic properties of Mn4N films are discussed, including the manipulations methods of different Mn4N heterostructures in recent years. The 4th part highlights the physical properties of Mn4N films doped with other metals, including Co, Ni, and other heavy metal elements. The 5th part illustrates the potential applications of Mn4N films based on the physical properties discussed before. Finally, challenges and future prospects for Mn4N films are discussed, which could provide guidance for developing novel applications and designing functional devices. [ABSTRACT FROM AUTHOR]

NiFe2O4 (NFO) is a soft magnetic material that is vital for various spintronic, biomedical, and energy-related applications. In this report, cubic inverse spinel NFO was investigated for its electronic structure, magnetic, and optical properties, and variations of these properties as a function of external hydrostatic pressure were determined in the framework of the Density Functional Theory using the CASTEP code. The NFO is a semiconducting ferrimagnetic material in the absence of externally applied hydrostatic pressure, however, this electronic and magnetic character changes steadily as the applied pressure is increased from 0 to 100 GPa. The bandgap value, lattice constant, and the net magnetic moment all decrease with increasing pressure. The electronic bandgap of NFO becomes zero and it becomes paramagnetic at the highest studied pressure of 100 GPa. The electronic structure was studied in detail with varying pressure, and it was indicated that the density of states Fe3+ at the octahedral sublattice showed a large splitting of 3d states with increasing pressure. This large decrease in the net magnetic moment can be attributed to the above-mentioned energy splitting. All optical constants were also observed to be affected by the external pressure. The conversion of O2− states from discrete/split to continuous may be the possible reason for the variation of optical properties. [ABSTRACT FROM AUTHOR]

Magnetic and flexible nanocomposites of polyamide 6 (PA6)/styrene‐(ethylene‐butylene)‐styrene grafted with maleic anhydride (SEBS‐MA) were prepared using Ni‐Zn ferrite synthesized by combustion reaction. Thermal treatment was applied to the Ni‐Zn ferrite to form a more crystalline phase. The nanocomposites were processed in an internal mixer and later injection molded. The materials were characterized by torque rheometry, X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Izod impact strength, tensile strength, magnetic measurements, differential scanning calorimetry (DSC), thermogravimetry (TG), heat deflection temperature (HDT), and scanning electron microscopy (SEM). Ferrite calcination led to a higher degree of crystallinity and nanocomposites with a higher number of crystalline peaks. This favored a higher saturation magnetization. The magnetic hysteresis curves of the nanocomposites indicated a ferrimagnetic behavior. The impact strength and elongation at break increased significantly compared to neat PA6, suggesting the formation of flexible and magnetic nanocomposites. This behavior was ascribed to a chemical reaction between the terminal amine groups of PA6 and the maleic anhydride of SEBS‐MA, confirmed by FTIR and torque rheometry. Neat PA6 and the nanocomposites showed similar thermogravimetric, HDT, melting temperature, and crystallization properties. SEM results showed that the dispersed ferrite tends to form agglomerates, especially if calcined. In general, the addition of the non‐calcined Ni‐Zn ferrite to the PA6 matrix improved the mechanical properties. Conversely, the calcination of ferrite tended to improve the magnetic behavior of the nanocomposites. [ABSTRACT FROM AUTHOR]

In this article, we report the observation of spin Seebeck effect (SSE) of hybrid structure in bulk sintering polycrystalline of yttrium iron oxide (Y3Fe5O12, YIG)/Pt. The bulk YIG polycrystalline is prepared by solid press mechanic and then coated with Pt 10 nm thickness. The voltage of inverse spin Hall effect (VISHE) in Pt/YIG polycrystalline is detected by in plane magnetization configuration (IM) and then filter out the anomalous Nernst effect (ANE) by perpendicular magnetization configuration (PM). The results show that the VISHEsignal can be observed in bulk YIG polycrystalline. In addition, the efficiency of spin injection from YIG to Pt is compared between Pt/YIG single crystal and bulk polycrystalline of hybrid structure. The VISHE signal of Pt/YIG single crystal and bulk polycrystalline are 197.61 nV/K and 23.22 nV/K, respectively. The VISHEvoltage of YIG single crystal is higher than bulk polycrystalline about 9 times. Whereas, the porous size in bulk YIG polycrystalline of solid press is determined around 214 ± 81 nm but it cannot detect in YIG single crystal. Thus, the porous size and surface roughness between YIG and Pt might be the major role of the spin current (Js) transfer. [ABSTRACT FROM AUTHOR]

The ferrimagnetic nodal-line semiconductor Mn 3 Si 2 Te 6 , featuring a quasi-two-dimensional crystal structure, has attracted significant attention owing to its rich physical properties. Here, we systematically investigate the magnetic properties of its isostructural compound, Mn 3 Si 2 Se 6. The magnetism of this material is attributed to the Mn atoms, which exhibit antiferromagnetic interactions among the Mn atoms. The competition between antiferromagnetic exchange interactions results in an overall ferrimagnetic state, with a second-order transition from paramagnetic to ferrimagnetic occurring at 68 K. Critical exponents are derived using various common experimental techniques, including the modified Arrott plot, Kouvel-Fisher method, and critical isotherm analysis. The results indicate that the magnetism of Mn 3 Si 2 Se 6 closely aligns with the mean-field model, with critical exponents β , γ , and δ determined as 0.475(3), 1.059(3), and 3.20(1), respectively, at the critical temperature of 68.3(2) K. Moreover, the curves of the magnetic entropy change − Δ S M (T , H) exhibit a peak around T c , with − Δ S M max amounts to 4.61 (3.63) J kg−1 K−1 for H ∕∕ ab (∕∕ c) with a field change of 7 T. The estimated magnetic entropy value near T c through specific heat is remarkably saller than the expected spin entropy of Mn2+ ions, indicating the presence of short-range interactions in the paramagnetic region. • The competition exchange interactions result in an overall ferrimagnetic state in Mn 3 Si 2 Se 6. • Magnetism of Mn 3 Si 2 Se 6 aligns with the mean-field model. • Specific heat analysis reveals short-range interactions in Mn 3 Si 2 Se 6 's paramagnetic region. [ABSTRACT FROM AUTHOR]

Density Functional Theory (DFT) calculations are performed using full potential linearized augmented plane wave (FP-LAPW) method to study CoTiFeGe and Co 2 Fe 0.25 Mn 0.75- x Ti x Ge (x = 0, 0.25, 0.50, 0.75) systems through GGA and mBJ-GGA formalisms. The lattice equilibrium optimization was conducted to determine the stable magnetic phase state of these systems. It was found that the systems exhibit stability in a ferromagnetic nature, with the exception of the Co 2 Fe 0.25 Mn 0.75 Ge compound, which displays ferrimagnetic behavior. Electronic band structures and density of states for our systems show a half-metallic character using mBJ-GGA, except the Co 2 Fe 0.25 Mn 0.75 Ge system, which exhibits metallic behavior. Furthermore, the studied systems adhere to the Slater-Pauling rule condition for half-metallicity of alloys M tot = Z V -24. Optoelectronic properties have been analyzed using optical parameters, confirming semiconducting behavior. Optical reflections with minimal loss and the existence absorption are observed in the infrared and visible areas suggest that the studied systems are suitable for optoelectronic devices. Additionally, a comprehensive assessment of the thermodynamic properties of the systems was carried out to investigate their thermodynamical stability against temperature and pressure change. The transport properties of these systems were systematically investigated, revealing that our alloys present the poor thermoelectric matter. [Display omitted] • Study of thermoelectric and thermodynamic properties of two systems. • Ferromagnetic for x = 0.25, 0.50 and 0.75 and Co 2 Fe 0.25 Mn 0.75 Ge is ferrimagnetic. • Maximum spin polarization informs that the studied systems present half-metallic. • Gibbs program and are evaluated as functions of temperature at zero pressure. • Transport coefficients of the considered alloy have been investigated. [ABSTRACT FROM AUTHOR]

The contradictory relationship between magnetism and ductility restricts further applications of FeCoV alloys in high-performance electrical machines. The role of the BCC-B2 transition, accompanied by vanadium (V) site occupancies, in magnetic moments and ductility has been explored using first-principles calculations. The variations in magnetism and ductility of FeCoV alloys are attributed to the coupling of the BCC-B2 transition and V occupancies. When V replaces Fe atoms in the equiatomic B2-FeCo alloy, the superior magnetism observed in B2-Fe 50- c Co 50 V c alloys is a consequence of the enhanced local magnetic moment of Fe and the ferrimagnetic-ferromagnetic transition in the magnetic state. Moreover, due to the preferential V occupancy in the B2 phase, the B2-Fe 46 Co 50 V 4 alloy exhibits comparable ductility to the BCC-Fe 50 Co 46 V 4 alloy. The results indicate that the increased brittleness in the B2 phase arises from the raised Peierls stress and the enhanced covalent component in interatomic bonding, which is caused by the strong hybridization between Fe and Co atoms. Pearson correlation analysis illustrates that valence electron concentration (VEC) and V content are significant factors in the contradictory relationship between magnetization and ductility. The theoretical results demonstrate that tuning the V content and atomic occupancies is helpful to achieve a trade-off between magnetization and ductility in B2-FeCoV alloys. • The coupling effect of the BCC-B2 transition and V occupations on magnetic moment and ductility. • The underlying origins of magnetism-ductility contradictory relationship. • A trade-off between magnetic moment and ductility can be obtained in B2-Fe 46 Co 50 V 4 alloy. • the magnetization can be improved by adjusting VEC and V content. [ABSTRACT FROM AUTHOR]

• Ti2MnAl crystallizes with significant atomic disorder resulting in random mixing of constituent elements. • Atomic disorder plays an important role in determination of physical properties. • Ti2MnAl exhibits Pauli's paramagnetic behaviour. • Non-interacting superparamagnetic clusters emerge at low temperatures due to defects. • Disorder give rise to a negative temperature coefficient of resistivity. Search for novel spintronic materials in family of Heusler alloys has attained significant interest in recent years. In this context, Ti 2 MnAl is interesting as it is predicted to host spin gapless semiconducting state and compensated ferrimagnetic ordering. Here we report a detailed experimental investigation of Ti 2 MnAl. Our studies reveal that Ti 2 MnAl crystallizes in cubic structure with strong atomic disorder along with Pauli paramagnetic behaviour. The influence of disorder manifests in form of non-interacting superparamagnetic clusters at low temperatures and negative temperature co-efficient of resistivity. The carrier concentration obtained from Hall resistivity rules out the possibility of spin gapless semiconducting state. Our studies indicate that atomic disorder plays an important role in determination of physical properties of Ti 2 MnAl. [ABSTRACT FROM AUTHOR]

• Review on recent progress in magnetic properties of SrM magnet & it's applications. • Reviewed various synthesis processes and their effect on magnetic properties of SrM. • Covered substitutional behavior of various elements on magnetic properties of SrM. • Attempted to cover the possibility of SrM-based magnet in numerous applications. • The review paper is motivated towards an alternative to rare-earth permanent magnet. Hard magnets (HMs) are significant components in various applications like rotating machines, telecommunication, computer devices, sensors, and many more. In the HM group, permanent magnets are extensively used due to their high energy product, though they are costly and contain rare earth (RE) elements. Advancements in the magnetic properties of non-RE-based hard magnets can fulfill the technology gap between non-RE and expensive RE-based hard magnets. Hexaferrite magnets represent the largest magnet group being used nowadays by volume, in which strontium hexaferrite (SrM) is a widely used non-RE hard magnet. It is the most faithful base magnet in terms of abundance and economic balance, which requires more or less reformation and advancement in the aspect of magnetic properties. SrMs are ferrimagnetic materials, and their magnetic properties are inherently linked to the microstructures. It can be upgraded to attain high (BH) max and high curie temperature by refining its magnetic properties. Improvement in its M s and H c , even mildly, could open up the possibilities of large-scale immersion of strontium hexaferrite-based magnets in the vast field of permanent magnet applications. In the past several years, enormous improvement has been made toward enhancing the physical and magnetic properties of SrM. Identifying the synthesis parameters as well as the microstructural changes is essential for designing and improvisation of magnets. The current progress in the magnetic properties of SrM (especially high M s and high H c) by synthesis parameters and different substituting elements is briefly covered in this review, along with the applications and future aspects of Sr-hexaferrite-based magnets. [ABSTRACT FROM AUTHOR]

Development of antiferromagnetic/ferrimagnetic materials has been an area of active pursuit to advance the antiferromagnetic/ferrimagnetic spintronics. In this paper, we investigated the emergence of the spontaneous magnetization M S in the antiferromagnetic Cr 2 O 3 thin film by the Al substitution. In the case of the (Cr 1- x Al x) 2 O 3 (0001) thin films, M S increases with increasing Al composition x up to x ∼0.21. The magnitude of M S decreases abruptly for x > 0.22, accompanied with the collapse of the crystal formation. We found that the induction of the spontaneous magnetization was highly associated with the growth process. The magnitude of M S depends on the growth direction of the film: M S at 10 K for x = 0.13±0.01 is 80 kA/m, 30 kA/m and 0 kA/m for (0001), (01 1 ¯ 2) and (11 2 ¯ 0) films, respectively. The difference in M S with the growth direction is relevant to the magnetic sublattice selective substitution of Al during the thin film growth. This specific substitution occurs in the growth plane having the layer-by-layer stacking of the magnetic sublattice, which was verified by the direct observations using the scanning transmission electron microscope. [Display omitted] [ABSTRACT FROM AUTHOR]

This work used two approaches of mechanical alloying before high temperature solid state reaction to synthesize BaFe 12-x Sc x O 19 (x = 0.5 to 6.0) system. Rietveld refinement of X-ray diffraction patterns showed the formation of extra phases at higher Sc doping, along with the main magnetoplumbite structure. Raman spectroscopy suggested random distribution of Sc ions at the Fe-sites of hexaferrite structure. X-ray photoelectron spectroscopy (XPS) confirmed the +3 charge state at the Fe/Sc-sites. The Fe 3s band suggested dilution of ferromagnetic 3s-3d spin exchange interactions. The neutron diffraction study re-confirmed random occupancy of the non-magnetic Sc3+ ions at Fe3+ sites of the Sc doped Ba hexaferrite system. The transformation of magnetic spin order from collinear to non-collinear state has shown spin glass-like features at low temperature regime in the dc magnetization curves. This is an effect of dilution of Fe– O –Fe ferrimagnetic super exchange interactions and spin frustration in Sc-doped samples. [Display omitted] [ABSTRACT FROM AUTHOR]

We used Monte Carlo simulation to study the magnetic properties and compensation behavior of a ferrimagnetic mixed-spin (3 / 2 ; 1 / 2) Ising system in a graphene bilayer. The effects of exchange interactions, crystal field, external magnetic field and temperature on the total magnetization, partial magnetizations, magnetic susceptibility, phase diagram and hysteresis behavior of the system were examined. Interesting results were obtained in this work, such as the compensation behavior and the multi-loop hysteresis phenomenon for specific values of the system's physical parameters. Our results conform to those of other theoretical studies. • The compensation and critical behaviors of a Graphene Bilayer were investigated. • Different total magnetization profiles are observed in this ferrimagnetic system. • The effect of various physical parameters on hysteresis behavior was presented. [ABSTRACT FROM AUTHOR]

Using DFT and Monte Carlo simulation, we studied the physical properties of the ferrimagnetic half-metal Mn 2 RhSi Heusler alloy. Our calculations reveal a stable face-centered cubic structure without any possibility of martensitic transition. The electronic structure shows half-metallic behavior with a band gap in spin-down of 0. 49 eV calculated using PBE and 0. 85 eV using the r 2 SCAN functional, and antiferromagnetic–ferromagnetic coupling with a Curie temperature of 460 K. The elastic constants and moduli decrease with temperature due to thermal expansion, but Mn 2 RhSi retains its mechanical stability. The dominance of metallic bonds, large band gap, high Curie temperature, low magnetic moment, and good mechanical properties make Mn 2 RhSi a promising candidate for spintronic applications at room temperature. • Mn 2 RhSi is an inverse Heusler ferrimagentic half-metal. • According to the r2SCAN functional, Mn 2 RhSi has a spin-down gap of 0.85 eV. • Curie temperature of Mn 2 RhSi calculated using Monte Carlo simulation is 460 K. • Mechanical properties indicate that Mn 2 RhSi is mechanically stable and ductile over the temperature range of 0–1000K. • The wide gap and Curie temperature above room temperature suggest that Mn 2 RhSi can be suitable for spintronic applications. [ABSTRACT FROM AUTHOR]

A comprehensive study on growth of ferrimagnetic manganese zinc ferrite (Mn0.5Zn0.5Fe2O4) films on single crystalline strontium titanate(001) (SrTiO3) substrates was carried out. Under the optimized conditions, a thin film with a layer thickness of 200 nm was deposited, and the structural properties were investigated. Contrary to data published in literature, no buffer layer was necessary to achieve epitaxial growth of a poorly lattice-matched layer. This was confirmed for Mn0.5Zn0.5Fe2O4(001) on SrTiO3(001) by x-ray diffraction and the adjoined phi scans, which also revealed a lattice compression of 1.2% of the manganese zinc ferrite film in the out-of-plane direction. Using x-ray photoelectron spectroscopy, the near surface stoichiometry of the film could be shown to agree with the intended one within the uncertainty of the method. X-ray absorption spectroscopy showed an electronic structure close to that published for bulk samples. Additional x-ray magnetic circular dichroism investigations were performed to answer detailed structural questions by a comparison of experimental data with the calculated ones. The calculations took into account ion sites (tetrahedral vs. octahedral coordination) as well as the charge of Fe ions (Fe2+ vs. Fe3+). Contrary to the expectation for a perfect normal spinel that only Fe3+ ions are present in octahedral sites, hints regarding the presence of additional Fe2+ in octahedral sites as well as Fe3+ ions in tetrahedral sites have been obtained. Altogether, the layer could be shown to be mostly in a normal spinel configuration. [ABSTRACT FROM AUTHOR]

A comprehensive numerical study of the spin toque driven dynamic states is presented for a synthetic ferrimagnet. For this, the Landau-Lifshitz-Gilbert equation has been solved simultaneously for the two coupled layers of the synthetic ferrimagnet in a macrospin approach including the spin transfer torque term from an external polarizer for one of them. It is shown that a large variety of dynamic modes (in-plane precession (IPP) and out-of-plane precession) can be established, upon varying the strength of the exchange bias field that pins one of the layers of the SyF as well as the Ruderman- Kittel-Kasuya-Yosida interlayer coupling strength. The current--field state diagrams are presented as well as the frequency current dependencies of the most important mode which is the IPP mode. A characteristic feature of the IPP mode for the coupled system (as compared to single layer excitations) is the change, increase or decrease of the frequency, with current upon increasing field. It is shown that this strongly depends on the asymmetry of the internal fields that the two layers experience, upon varying either their thickness or the exchange bias field. [ABSTRACT FROM AUTHOR]

We report the low-temperature anomalous magnetic behavior of ferrimagnetic spinels cobalt orthotitanate (Co2TiO4), which exhibits magnetic compensation behavior across 31.74 K, and cobalt orthostannate (Co2SnO4) exhibiting two sequential magnetic transitions, namely (i) ferrimagnetic to paramagnetic transition with Néel temperature TN∼41K and reentrant spin-glass behavior with glass transition temperature TSG∼39 K. The Arrott plot (H/M versus M²) criterion has been used to extricate the order of sequential magnetic transitions occurring below TN. Negative slopes of the Arrott plots below 32 K, metamagnetic-like character of the M-H isotherms, anomalies in the specific-heat (CP T-1 versus T) below 15 K, and a zero-crossover of isothermal magnetic-entropychange (ΔS) signify the presence of pseudo first-order discontinuous magnetic phase transition in the low-temperature regime 5K≤T≤32 K. The dc- and ac-susceptibilities of both Co2TiO4 and Co2SnO4 are interpreted in terms of frozen-spin-clusters, which are responsible for very large magnitudes of the coercivity HC∼20 kOe and bipolar-exchange bias HEB∼=-20 kOe observed below 10 K. [ABSTRACT FROM AUTHOR]

We investigate the switching field distribution and the resulting bit error rate of exchange coupled ferri-/ferromagnetic bilayer island arrays by micromagnetic simulations. Using islands with varying microstructure and anisotropic properties, the intrinsic switching field distribution is computed. The dipolar contribution to the switching field distribution is obtained separately by using a model of a triangular patterned island array resembling 1:4Tb=in² bit patterned media. Both contributions are computed for different thicknesses of the soft exchange coupled ferrimagnet and also for ferromagnetic single phase FePt islands. A bit patterned media with a bilayer structure of FeGd(5 nm)/FePt(5 nm) shows a bit error rate of 10-4 with a write field of 1:16T. [ABSTRACT FROM AUTHOR]

The current work reports an unprecedented multifunctional material with optical activity and a modified magnetic response by a unique combination of doping with P and Fe into the spinel LiMn 2 O 4. Through inductively coupled plasma – optical emission spectroscopy, X-ray absorption near-edge spectroscopy, X-ray diffraction and scanning transmission electron microscopy, the chemical composition, oxidation state and the crystalline structure are determined. Solid-state UV-Vis spectroscopy, magnetic susceptibility and electronic conductivity reveal the critical importance of the interaction between iron and phosphorus when simultaneously doping the crystalline structure of LiMn 2 O 4. The presence of Fe and P considerably increases charge carrier concentration as a mechanism for enhancing electronic conductivity. Fe and P doping also creates Fe-Fe spin interactions that allow double electron optical excitations. This opens a pathway to create multifunctional materials for light-assisted charging lithium-ion batteries. P doping also induces the formation of magnetic clusters arising from the Fe-O-Fe, Fe-O-Mn and Mn-O-Mn spin exchange interactions. The magnetic response of the materials is strongly influenced by the relative amount of Fe in octahedral or tetrahedral sites of the spinel structure. Such ferrimagnetic behaviour has not been reported before LiMn 2 O 4 doped with Fe or P separately. The potential applicability of this newly identified magnetic feature was demonstrated by a significant capacity gain when a lithium-ion cell is exposed to a static external magnetic field. • Simultaneous P and Fe doping of the LiMn 2 O 4 spinel develops new ferro/ferrimagnetic properties in this material. • Phosphorous stabilizes iron-iron magnetic interactions, unseen in previous Fe doped LiMn 2 O 4. • Iron-iron magnetic interaction gives rise to double optical electron excitation and ferro/ferrimagnetic features. • Under magnetic field, ferromagnetic P and Fe doped LiMn 2 O 4 delivers higher capacity gains than other generic LIB materials. • Enhanced capacity gains occur due to an increased magnetohydrodynamic effect on the surface of the particles. [ABSTRACT FROM AUTHOR]

In this theoretical study, we investigate novel quaternary Heusler Fe–Rh–Mn–Al alloys in the X-type structure with different types of atomic ordering in the unit cell within the spin-polarized density functional calculations. The calculations showed that the 24 possible configurations converge to the 6 nonequivalent solutions. Two types of atomic ordering with the lowest total energy Fe(4c)Rh(4d)Al(4b)Mn(4a) and Mn(4c)Al(4d)Fe(4b)Rh(4a) are half-metallic ferrimagnets in which the spin polarization at the Fermi level is close to 100 %. However, no gap is open in the majority spin projection. The following values of the total magnetic moments for these alloys were obtained: 3.01 and 3.19 μ B /f.u., respectively. In the other types of atomic ordering, the half-metallic state is not formed. In FeAlRhMn, the magnetic moment on the manganese ion compensates for the moments on the other ions, and the total moment is close to zero. In the types (MnFeRhAl, AlRhFeMn) of atomic ordering with high energies, the metallic state is also realized, and the magnetic moments on the ions are ordered ferrimagnetically. In this work, we analyzed novel quaternary alloys with different types of atomic ordering motivated by the demand for alloys with a high spin polarization, among which the FeRhAlMn and MnAlFeRh alloys were found. Both with a half-metallic ferrimagnetic state and the lowest total energy among these alloys with the same chemical composition, which indicates the stability of the half-metallic state. The other types of atomic ordering are less energetically favorable, those alloys are ferrimagnetic metals with the low spin polarization. Taking into account the half-metallic state and high spin polarization, the quaternary FeRhAlMn and MnAlFeRh alloys have prospects for use in spintronic devices. [ABSTRACT FROM AUTHOR]

Mn 1.17 Co 1.83 BO 5 and Mn 1.39 Co 1.61 BO 5 ludwigites were synthesized by the flux technique and investigated by means of X-ray diffraction, X-ray fluorescence, DC and AC magnetic susceptibility, and specific heat analysis. The crystal structure of both ludwigites belongs to the Pbam space group with a = 9.25 Å , b = 12.41 Å , and c = 3.05 Å for Mn 1.17 Co 1.83 BO 5 and a = 9.27 Å , b = 12.45 Å , and c = 3.05 Å for Mn 1.39 Co 1.61 BO 5. The simultaneously observed negative values of the Curie-Weiss temperatures and ferromagnetic-type hysteresis loops allow us to assume that the ferrimagnetic ordering is realized in Mn 1.39 Co 1.61 BO 5 below T F = 60.8 K, while in Mn 1.17 Co 1.83 BO 5 in addition to the above mentioned experimental facts the frequency dependencies of the real and imaginary parts of the AC magnetization were observed assuming the presence of the canonical spin-glass state below T SG = 44.5 K. The observed difference in coercive forces of M-H curves at low temperatures can be associated with presence of two spin subsystems for Mn 1.17 Co 1.83 BO 5. • Ludwigites Mn 1.17 Co 1.83 BO 5 and Mn 1.39 Co 1.61 BO 5 has been grown using flux method and then turned to powder. • An exchange bias was observed in Mn 1.17 Co 1.83 BO 5. • Measurements show spin-glass transitions at 44.3K for Mn 1.17 Co 1.83 BO 5 and ferrimagnetic transition at 60.8K for Mn 1.39 Co 1.61 BO 5. • The effective magnetic moments per unit cell are μ eff = 8.06 μ B for Mn 1.17 Co 1.83 BO 5 and μ eff = 9.03 μ B for Mn 1.39 Co 1.61 BO 5. • Co3+ ions taking 0.38 of 3 + position for Mn 1.17 Co 1.83 BO 5 and completely fill 3 + position for Mn 1.39 Co 1.61 BO 5. [ABSTRACT FROM AUTHOR]

A new A-site columnar-ordered quadruple perovskite, Gd 2 CuZnMn 4 O 12 , was synthesized by a high-pressure, high-temperature method at 6 GPa and 1500 K. Its structural properties between 100 K and 800 K were investigated by synchrotron powder X-ray diffraction. It has space group Pmmn (No. 59) between 100 K and about 450 K with a layered charge order (CO) of Mn3+ and Mn4+ cations at the perovskite B sites and space group P 4 2 / nmc (No. 137) above 475 K with one perovskite B site (having an average manganese oxidation state of +3.5). Anisotropic thermal expansion was observed as the c lattice parameter decreases with increasing temperature above 325 K. Temperature dependence of the unit-cell volume and the lattice parameters and differential scanning calorimetry measurements gave evidence that the CO transition (with T CO ≈ 475 K) is of the second order. Gd 2 CuZnMn 4 O 12 shows a ferrimagnetic transition below T C = 105 K with an additional decrease of magnetic susceptibilities below about 45 K, probably caused by a gradual increase of the ordered moments on the Gd sublattices coupled antiferromagnetically with the existent ferrimagnetic structure. Temperature dependence of the lattice parameters in Gd 2 CuZnMn 4 O 12. [Display omitted] • A-site columnar-order perovskite Gd 2 CuZnMn 4 O 12 was prepared. • The compound was synthesized with a high-pressure, high-temperature method. • A new combination of cations, Gd/Cu/Zn, was used for triple A-site order. • A second-order charge order transition was found below 475 K. • Ferrimagnetic long-range order at T C = 105 K takes place. [ABSTRACT FROM AUTHOR]

The current theoretical study explores the physical properties of quaternary Heusler ferrimagnetic semiconductors, specifically CrVTiAl, CrVZrAl, and CrVHfAl. Using first-principles calculations, we conduct a comprehensive analysis of the structural, electronic, and thermoelectric properties at different temperatures (300 K , 600 K , and 900 K) employing the r 2 SCAN functional. Furthermore, we investigate the impact of various types of doping on thermoelectric performance and efficiency of these Heusler compounds. Our results demonstrate the tunability of the thermoelectric properties of these Heusler compounds, emphasizing the critical role of carrier concentration, and provide valuable insights for the design and improvement of thermoelectric properties for thermoelectric applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The electronic, magnetic, and optical properties of MnFe 2 O 4 are studied through first-principles calculations. • The intricate chemical interactions of Mn-O and Fe-O bonds grounded in the multi-orbital hybridizations are thoroughly investigated in this article. • The optical properties, with a particular focus on prominent peaks that exhibit direct correlations with band transitions and spin configurations are an appealing research. • Various computational methods, encompassing local-density approximations (LDA), LDA + U, Perdew, Burke, Ernzerhof (PBE), and PBE + U, are considered to compare the electronic band gap and magnetic moments of MnFe 2 O 4. MnFe 2 O 4 represents a notable spinel ferrite material that synergistically combines the benefits of both Fe- and Mn-based materials. This compound emerges as a potential candidate for diverse applications encompassing biomedical techniques like thermotherapy, energy storage mechanisms such as lithium-ion batteries and supercapacitors, and advancements in optoelectronics and optical devices. Comprehensive first-principles calculations have been employed to delve into the structural, electronic, magnetic, and optical properties of MnFe 2 O 4. The intricate chemical interaction of Mn-O and Fe-O is elucidated via charge and spin features. This study meticulously examines distinct energy bands, spatial charge distributions, specific van Hove singularities, and configurations separated by spin orientation. Preliminary findings categorize the material as a semiconductor exhibiting ferrimagnetic traits. Among the computational methodologies utilized, including local-density approximations (LDA), LDA + U, Perdew, Burke, Ernzerhof (PBE), and PBE + U, the latter method shows a band gap of 1.017 eV, in contrast to the narrower gaps identified by alternative approaches. Crucially, the pronounced multi-orbital interactions spanning [4s, 3 d x 2 - y 2 , 3d xy , 3d yz , 3d xz , 3 d z 2 ] and [2s, 2p x , 2p y , 2p z ] offer insights into the fundamental physicochemical interactions of Fe-O and Mn-O. This article also presents and deliberates on the optical properties, emphasizing peaks that correlate directly with band structures and spin configurations. [ABSTRACT FROM AUTHOR]

Ab initio calculations are used in the present study to analyze the structural, magnetoelectronic, mechanical, thermal, thermoelectric, optical and thermodynamic properties of AMnBi 2 compounds (where A = Ca and Sr). The calculations use the density functional theory involving the Full Potential –Linearized Augmented Plane. Wave and the Monte Carlo simulation. We have used the Generalized Gradient Approximation (GGA) with Perdew-Burke-Ernzerhof (PBE) functional for modelling the exchange-correlation potential with Hubbard correction (GGA + U) was employed. The bulk modulus, its first derivative, and the optimal lattice parameters have been found. Both compounds display metallic nature. The electronic transport coefficients have been calculated. The entropy, thermal expansion coefficient, Debye temperature, and heat capacities C v and C p are calculated. The elastic constants at zero pressure, the bulk modulus B, and the shear modulus G have been evaluated. The Young's modulus and Poisson's ratio of two compounds have been performed. The Debye temperature is also approximated from the average sound velocity. The Néel temperature, magnetization, and hysteresis cycles are found. [ABSTRACT FROM AUTHOR]

In this study, SiCp(CNT) hybrid reinforcements were prepared by in-situ growth of CNTs on the SiCp surface by chemical vapor deposition (CVD) process. The yield strength (YS) and ultimate tensile strength (UTS) of SiCp(CNT)/7075Al were significantly improved by compensating Mg into the SiCp(CNT)/7075Al composites. The results showed that the SiCp(0.5CNT)/7075Al–Mg composites exhibited the best balance of strength and ductility at a Mg compensation of 1.0 wt %, not only the UTS (∼651 MPa) was higher than that of SiCp/7075Al-1.0 Mg, but also the elongation (3.5 %) was improved by more than 20 %. This is attributed to the fact that the Mg compensation can effectively improve the aging precipitation behavior of the interfacial micro-zones of SiCp(CNT)/7075Al–Mg, allowing it to be effectively strengthened and thus to transfer the load adequately and give full play to the strengthening effect of the SiCp(CNT) hybrid reinforcement. In addition, the toughness of the SiCp(CNT)/7075Al composites was significantly higher than that of SiCp/7075Al with or without the compensation of Mg. Further studies showed that the toughening mechanism of CNTs is divided into the following three main points: (1) the introduction of CNTs can effectively strengthens the interfacial micro-zones, thus retarding the crack initiation. And CNTs can redirect the motion of cracks through the initiation of daughter cracks; (2) the bridging, pull-out and fracture of CNTs can cause the composites to consume more energy during deformation; (3) the introduction of CNTs can effectively prolong the crack propagation path and make the deformation around SiCp more uniform. • The compensation of Mg can effectively improve the mechanical properties of SiCp(CNT)/7075Al composites. The SiCp(0.5CNT)/7075Al-1.0Mg composite exhibited the best balance of ultimate tensile strength (UTS) and ductility, with not only higher UTS than SiCp/7075Al-1.0Mg, but also an elongation increases of more than 20%. • The yield strength (YS) and UTS of SiCp(0.5CNT)/7075Al-1.0Mg composites were improved by 17.5% and 12.1%, respectively, compared to SiCp(0.5CNT)/7075Al. This is attributed to the fact that the compensation of Mg significantly improves the aging precipitation behavior near the interface and enhances the density of the η′-phases within the interfacial micro-zones. • The toughening mechanism of CNTs is mainly attributed to the following three points: (1) the introduction of CNTs can effectively retard the initiation of cracks and redirect the motion of cracks; (2) the bridging, pull-out of CNTs can effectively restrain the rapid crack propagation; (3) the introduction of CNTs can effectively prolong the crack expansion path and restrain the coarsening of cracks. [ABSTRACT FROM AUTHOR]

The influence of external pressures on the structural and magnetic properties of the FeNi alloy is elucidated using density functional theory (DFT) and Monte Carlo simulation. Utilizing a range of pressures, the study showcases compressive behavior in lattice constants, with both a and c exhibiting reductions. A sharp decline in magnetic moments is recorded at a critical pressure of 54 GPa. Indicating a magnetic phase transition from ferro to paramagnetic phase. Beyond this critical pressure, dynamical instability becomes evident, attributable to the aforementioned magnetic phase transition. Further examination of exchange interaction parameters reveals that while Fe–Fe interactions exhibited a consistent decrease with pressure, the FeNi and NiNi interactions remained relatively stable across the examined pressure range. At pressures close to 0 GPa, the Curie temperature (T C) was found to be around 838 K. As the external pressure is applied, a consequential decline in T C is witnessed, suggesting a significant sensitivity of the magnetic phase transition to external pressures. In particular, this study indicates that the FeNi alloy is sensitive to external pressures, emphasizing some relation between structural and magnetic properties. [Display omitted] • A comprehensive examination of the influence of external pressure on the properties of the FeNi alloy has been conducted. • A magnetic phase transition from a ferromagnetic to a paramagnetic state has been observed at a critical pressure of 54 GPa. • There is a decrease in the Curie temperature as the applied external pressure is increased. [ABSTRACT FROM AUTHOR]

Cobalt ferrite (CoFe 2 O 4) nanoparticles have been synthesized using two different wet-chemical methods: co-precipitation and solvothermal. Mesoporous cobalt ferrite nanoparticles were prepared using the co-precipitation method with 4, 6, and 8 wt% of Pluronic P123 and with the solvothermal method with 10, 15, and 20 wt% of PEG-4000. X-ray diffractometry confirmed the formation of a single-phase spinel structure. The saturation magnetization of the nanoparticles increased from 48 to 64 emu/g as the P123 concentration increased from 4 to 8 % wt, and decreased from 72 to 62 emu/g as the PEG-4000 concentration increased from 10 to 20 % wt. Generally, the samples synthesized by the solvothermal method had a higher specific surface area than those prepared by the co-precipitation method. In comparison to other samples, the 10 % PEG-4000 sample had the highest specific surface area and showed the highest level of dye degradation (93 %). The findings demonstrated that the concentration of Pluronic P123 and PEG-4000 had an impact on the saturation magnetization and specific surface area of the nanoparticles. [Display omitted] • Pure CoFe2O4 was successfully synthesized utilizing two separate chemical processes: solvothermal and co-precipitation. • The microstructure of the cobalt ferrite nanoparticles produced by both procedures is spherical and porous. • The solvothermal method yielded samples with a larger specific surface area than the co-precipitation method. • The magnetic properties in the system rises as P123 grows and falls as PEG-4000 increases. • Cobalt ferrite nanoparticles were ferrimagnetic, with saturation magnetization ranging from 42 to 72 emu/g. [ABSTRACT FROM AUTHOR]

The flow behavior, dynamic recrystallization (DRX), and microstructure evolution during the hot deformation of a newly developed 15Cr-30Ni-2Ti-3Cu valve alloy were studied. A constitutive model after strain compensation was established to predict the flow behavior of the alloy. A DRX kinetic model was proposed to predict dynamic recrystallization behavior during hot deformation. Both the fraction of DRX and the recrystallized grain size increases as the deformation temperature is increased from 950 ℃ to 1150 ℃, and decreases with increasing the strain rate from 0.01 s−1 to 10 s−1. A complete recrystallization structure of the alloy is obtained at the hot deformation temperature of 1150 ℃ and the strain rates smaller than 0.1 s−1. The optimal processing parameters of the valve alloy are determined as 1050 ℃− 1150 ℃/0.01 s−1-0.1 s−1. The Laves phase and (Ti,Nb)C particles precipitate during hot deformation, and hinder the dynamic recrystallization process by pinning dislocations and grain boundaries. Fine γ' particles provide nucleation sites for the formation of dynamically recrystallized grains due to its ordered cubic L1 2 structure. • Arrhenius-type constitutive model and dynamic recrystallization kinetics model was established. • The hot working processing map was established to determine the optimal hot working window. • The evolution of microstructure and precipitated phase during hot deformation were studied. • The DRX microstructure were analyzed by EBSD. [ABSTRACT FROM AUTHOR]

• The Ta/GdFeCo/Ta heterostructures are utilized to achieve a spin–orbit torque-driven multistate magnetization switching. • The switching ratio is up to 47.7% and the β DL and β FL are estimated as 85.64 Oe/(107 A/cm−2) and 35.05 Oe/(107 A/cm−2), respectively. • The findings establish that a stable four-resistor state exists, proofing multilevel memory behaviors and synaptic plasticity under current drive. • Neuromorphic computing built from this SOT device can perform unsupervised handwritten digit recognition with an accuracy of 92.25%. Neuromorphic computation of ferrimagnetic materials as artificial synapses is essential for the development of ultra-low power spintronic devices. Here, Ta/GdFeCo/Ta heterostructures are utilized to achieve a spin–orbit torque-driven multistate magnetization switching, complying with the requirements of neuromorphic computation. For Ta/GdFeCo/Ta device, the switching ratio is up to 47.7 % when the critical current density value is 1.26 × 107 A/cm2. Moreover, the β DL and β FL are estimated as 85.64 Oe/(107 A/cm−2) and 35.05 Oe/(107 A/cm−2), respectively. Subsequently, the findings establish that a stable four-resistor state exists, proofing multilevel memory behaviors and synaptic plasticity under current drive. It is further demonstrated that neuromorphic computing built from this SOT device can perform unsupervised handwritten digit recognition with an accuracy of 92.25 %. This research highlights the potential of SOT-driven multi-energy stabilized residual states for neuromorphic computing and multi-energy storage in the future. [ABSTRACT FROM AUTHOR]

• Gd-content gradients influence PMA in both "+δ" and "−δ" samples. • "+δ" has lower H C due to closer T comp , suggesting different Gd-content. • Reversal of AHE loop near T comp indicates sublattice dominance shift. • Decrease in H SF suggests weakened exchange interaction near T comp. • Strong ΔR XY at ± 4 kOe and ± 30 kOe for "−δ" indicates enhanced PMA. Ferrimagnetic rare-earth (RE) – transition-metal (TM) alloys are considered small ferromagnets with antiferromagnetic exchange in sublattices, which makes them a preferable choice for future ultrafast memory-related applications. Here, we explore the magnetic properties of two GdFeCo thin films with tailored vertical composition gradients, achieved by gradually varying Gd concentration across the film thickness. The temperature-dependent magnetic behavior of these films is investigated using anomalous Hall effect (AHE) measurements and SQUID magnetometry. Both films exhibit perpendicular magnetic anisotropy with distinct coercivities, indicating variations in their magnetic properties. The films show RE-dominant behavior at 300 K. Moreover, for the positive composition gradient (+δ) film, the compensation temperature is around 350 K, while the film with a negative gradient (−δ) exhibits a compensation temperature above 400 K. Furthermore, the spin-flop behavior and AHE sign reversal provide insights into the sublattice dominance and exchange interactions within the films. The magnitude of ΔR XY (the difference in AHE resistance at different magnetic fields) is shown to be sensitive to the composition gradient, indicating stronger perpendicular magnetic anisotropy for the "−δ" sample. This study demonstrates the potential of composition engineering to tailor the magnetic characteristics of ferrimagnetic materials for specific spintronics applications. [ABSTRACT FROM AUTHOR]

Exploring valley-contrasting physics in scarce intrinsic high-temperature ferromagnetic semiconductors with feasible synthesis route is of great significance for ever-evolving moden information technology. By first-principles calculations, the TiInTe 3 monolayer is predicted to demonstrate excellent structural stability and easy-plane semiconducting ferromagnetism arising from indirect superexchange mechanism. Monte Carlo simulations based on the Heisenberg model reveal a magnetic phase transition at 583 K well above room temperature. Due to the inversion and time-reversal asymmetries, tunable valley polarization in the conduction band up to 110 meV can be achieved by varying the magnetization orientation, which is further validated by a first-order perturbation theory. More excitingly, electron doping for realizing the anomalous valley Hall effect gives rise to an out-of-plane preference for magnetization in the TiInTe 3 monolayer and thus generates spontaneous and larger valley polarizations. After doping, the ferromagnetism above room temperature remains robust in the experimentally attainable electron density regime. Our findings highlight that the TiInTe 3 monolayer is a promising ferrovalley material for developing high-performance spintronic and valleytronic nanodevices. [Display omitted] [ABSTRACT FROM AUTHOR]

Peltier effects, which produce a heat flux at the junction of two different materials, have been an important technology for heating and cooling by electrical means. Whereas Peltier devices have advantages such as cleanliness, silence, compactness, flexibility, reliability, and efficiency, relatively complicated modular structures are unavoidable, leading to a higher cost than that of commonly used refrigeration technology. Here, we provide a concept of a Peltier device composed of a single magnetic material exhibiting a first-order magnetic transition. Our concept is based on a controllable junction structure consisting of two magnetic phases with opposite Peltier coefficients instead of a semiconductor junction. Using Mn 1.96 Cr 0.04 Sb samples with the first-order magnetic transition between ferrimagnetic (FI) and antiferromagnetic (AF) states, we successfully made a stable junction structure of AF/FI/AF by a pulse heating method and achieved a maximum Peltier coefficient of 0.58 mV. Our device concept was further verified by a numerical simulation based on a finite element method. The single-material Peltier effect reported here avoids a complex device design involving material junctions and is importantly reconfigurable. [ABSTRACT FROM AUTHOR]

A femtosecond laser pulse is able to switch the magnetic state of a 3d-4f ferrimagnetic material on a pico-second timescale. Devices based on this all-optical switching (AOS) mechanism are competitive candidates for ultrafast memory applications. However, a large portion of the light energy is lost by reflection from the metal thin film as well as transmission to the substrate. In this paper, we explore the use of dielectric coatings to increase the light absorption by the magnetic metal layer based on the principle of constructive interference. We experimentally show that the switching energy oscillates with the dielectric layer thickness following the light interference profile as obtained from theoretical calculations. Furthermore, the switching threshold fluence can be reduced by at least 80% to 0.6 mJ/cm2 using two dielectric SiO2 layers sandwiching the metal stack, which scales to 15 fJ of incident energy for a cell size of 502 nm2. [ABSTRACT FROM AUTHOR]

In order to ensure the safety and reliability of power system, more and more monitoring and maintenance equipment on transmission lines are being used. However, these equipment would not work without the supply of power. At present, the current transformer has been widely used in the on line power acquisition device. As an important part of the current transformer, the performance magnetic core has great influence on the power acquisition. In this paper, the core parameters of the current transformer in the on-line power acquisition device are designed, and the parameters such as core material and air gap length are optimized and verified by simulation as well. [ABSTRACT FROM AUTHOR]

Magnonics as an emerging frontier of spintronics aims using magnons to deliver information free from electron scattering and as-induced Joule heating. In general, magnon currents can be excited both thermally and electrically in magnetic insulators by applying a current in an adjacent heavy-metal layer. Here, we report another kind of magnon junctions (MJs) composed of Y 3 Fe 5 O 12 /CoO/ Y 3 Fe 5 O 12 heterostructures, in which Y 3 Fe 5 O 12 and CoO are, respectively, ferrimagnetic and antiferromagnetic insulators. A temperature gradient can drive a high (low) magnon current via the spin Seebeck effect when the Y 3 Fe 5 O 12 layers in an MJ are configured at the parallel (antiparallel) state, showing a spin valve-like behavior. Electrically injected magnon current could also be controlled by the MJs, contributing to a magnon-mediate nonlocal spin Hall magnetoresistance (SMR). Furthermore, compared with its NiO counterpart, both the magnon junction and magnon-mediate SMR effects can be clearly observed at room temperature for the CoO-based magnon junctions, which can possibly be applied as a building block for room-temperature magnon-based memory or logic devices. [ABSTRACT FROM AUTHOR]

Copper-containing ferrimagnetic glass-ceramic with the following composition: 24.7% SiO 2 -8.5% CaO-13.5% Na 2 O-3.3% P 2 O 5 -31% Fe 2 O 3 -14% FeO–5CuO (wt%) was synthesized by means melt and quenching process both in powder and bulk form. The obtained samples were characterized and compared by means morphological, compositional and structural analyses. The magnetic properties and the ability to release heat were also investigated together with the antimicrobial properties towards S. aureus strain. The obtained results showed that copper introduction and the annealing process influenced the nucleation of crystalline phases; in particular the samples produced in powder form evidenced a low amount of magnetite and thus a reduced hysteresis area and ability to produce heat when exposed to an alternating magnetic field. While Cu-containing samples in the bulk form maintained the magnetic and calorimetric properties of pristine glass-ceramic. Preliminary evaluation of antibacterial properties demonstrated Cu-doped samples were not able to reduce the bacterial proliferation and thus the need to optimize the copper introduction process. [ABSTRACT FROM AUTHOR]

Based on the Monte Carlo simulation, magnetic properties and magnetocaloric effects of a two-dimensional body-centered hexagonal structure with mixed spin (1/2, 1, 3/2) ferromagnetic ternary alloys of the type A y (B 1 - x C x) 1 - y were studied. To this end, concentration, temperature and an external magnetic field effects on the magnetization and magnetocaloric effect of these structures were examined. Our results indicate that concentration and external magnetic field play a crucial role in magnetic properties and magnetocaloric effect of these ternary alloys. Also, it is observed that A 0.2 (B 0.4 C 0.6) 0.8 compound has the largest cooling efficiency and thus is a suitable material for magnetic refrigerator. [ABSTRACT FROM AUTHOR]

Implementation of skyrmion based energy efficient and high-density data storage devices requires aggressive scaling of skyrmion size. Ferrimagnetic materials are considered to be a suitable platform for this purpose due to their low saturation magnetization (i.e. smaller stray field). However, this method of lowering the saturation magnetization and scaling the lateral size of skyrmions is only applicable where the skyrmions have a smaller lateral dimension compared to the hosting film. Here, we show by performing rigorous micromagnetic simulation that the size of skyrmions, which have lateral dimension comparable to their hosting nanodot can be scaled by increasing saturation magnetization. Also, when the lateral dimension of nanodot is reduced and thereby the skyrmion confined in it is downscaled, there remains a challenge in forming a stable skyrmion with experimentally observed Dzyaloshinskii–Moriya interaction (DMI) values since this interaction has to facilitate higher canting per spin to complete a 360° rotation along the diameter. In our study, we found that skyrmions can be formed in 20 nm lateral dimension nanodots with high saturation magnetization (1.30–1.70 MA/m) and DMI values (~ 3 mJ/m2) that have been reported to date. This result could stimulate experiments on implementation of highly dense skyrmion devices. Additionally, using this, we show that voltage controlled magnetic anisotropy based switching mediated by an intermediate skyrmion state can be achieved in the soft layer of a ferromagnetic p-MTJ of lateral dimensions 20 nm with sub 1 fJ/bit energy in the presence of room temperature thermal noise with reasonable DMI ~ 3 mJ/m2. [ABSTRACT FROM AUTHOR]

We investigate the Hall resistance of metallic multilayers Ta/Cr/CoTb/Ta/Si. In addition to the anomalous Hall effect originating from the ferrimagnetic CoTb layer, the unconventional Hall effect (UHE) is observed in our multilayer samples. The UHE depends not only on the current and magnetic fields but also on the device geometry and temperature in a unique way. Our results suggest that the UHE does not originate from the spin–orbit torque driven magnetization tilting but occurs possibly due to thermionic emission and Lorentz force at the metal/Si interface, where the Schottky barrier is formed. We also find that the space-charge effect causes geometric dependence of the Hall resistance. The magnitude of UHE is sizable and linearly proportional to the longitudinal magnetic field, suggesting that the observed UHE is attractive to the magnetic-field sensing industry. [ABSTRACT FROM AUTHOR]

The present study investigates the influence of Ca2+-Sc3+ co-dpoing on the magnetic properties of Sr1-x/12Cax/12Fe12-xScxO19 (x = 0.0 to 2.0) hexaferrites. The samples were prepared via a facile autocombustion technique followed by sintering in ambient air. X-ray powder diffraction patterns show the formation of the pure phase of M-type hexaferrite. The lattice parameters a and c increased with the Ca2+-Sc3+ doping. The compounds' magnetic properties were assessed as a function of temperature (10–300 K) and field (up to 6T). A rapid decline in room temperature coercivity from 5458 to 373 Oe and remanence value from 37 to 13 emu/g and a moderate decline in saturation magnetization from 76.9 to 57 emu/g were observed with increasing doping content from x = 0.0 to 2.0. The phase transition temperature, corresponding to ferrimagnetic to conical, was observed below 100 K, which disappeared at low doping content. The temperature-dependent behavior of magnetization and coercivity is discussed in view of spin non-collinearity due to the change in magnetic anisotropy. The Curie temperature dropped from 769 K at x = 0 to 568 K at the maximum substitution of x=2.0. The room temperature Mossbauer spectral analysis confirmed the preferred occupancy of Sc3+ at the 4f2 site and the influence of Ca2+ on the isomer shift values of the 2b site. The increased quadrupole shift values with the substitution implied distortion in 2b bipyramidal symmetry. The observed changes in magnetic properties and hyperfine parameters are ultimately tied to the preferred occupancy of Sc3+ at the spin-down 4f2 site. [ABSTRACT FROM AUTHOR]

Purpose: A "spin-diode" is the spintronics equivalent of an electrical diode: applying an external magnetic field greater than the limit of spin-diode BT flips the spin-diode between an isolating state and a conducting state [1]. While conventional electrical diodes are two-terminal devices with electrical current between the two terminals modulated by an electrical field, these two-terminal magneto resistive devices can generally be referred to as "spin-diodes" in which a magnetic field modulates the electrical current between the two terminals. Design/methodology/approach: Current modulation and rectification are an important subject of electronics as well as spintronics spin diode is two-terminal magnetoresistive devices in which change in resistance in response to an applied magnetic field; this magnetoresistance occurs due to a variety of phenomena and with varying magnitudes and directions. Findings: In this paper, an efficient rectifying spin diode is introduced. The resulting spin diode is formed from graphene gallium and indium quantum dots and antimony-doped molybdenum disulfide. Converting an alternating bias voltage to direct current is the main achievement of this model device with an additional profit of rectified spin-current. The non-equilibrium density functional theory with a Monte Carlo sampling method is used to evaluate the flow of electrons and rectification ratio of the system. Originality/value: The results indicate that spin diode displaying both spin-current and charge-current rectification should be possible and may find practical application in nanoscale devices that combine logic and memory functions. [ABSTRACT FROM AUTHOR]

Ferrimagnetic thin films are attractive for low‐power spintronic applications because of their low magnetization, small angular momentum, and fast spin dynamics. Spin orbit torques (SOT) can be applied with proximal heavy metals that also generate interfacial Dzyaloshinskii–Moriya interactions (DMI), which can stabilize ultrasmall skyrmions and enable fast domain wall motion. Here, the properties of a ferrimagnetic CoGd alloy between two heavy metals to increase the SOT efficiency, while maintaining a significant DMI is studied. SOT switching for various capping layers and alloy compositions shows that Pt/CoGd/(W or Ta) films enable more energy‐efficient SOT magnetization switching than Pt/CoGd/Ir. Spin‐torque ferromagnetic resonance confirms that Pt/CoGd/W has the highest spin‐Hall angle of 16.5%, hence SOT efficiency, larger than Pt/CoGd/(Ta or Ir). Density functional theory calculations indicate that CoGd films capped by W or Ta have the largest DMI energy, 0.38 and 0.32 mJ m−2, respectively. These results show that Pt/CoGd/W is a very promising ferrimagnetic structure to achieve small skyrmions and to move them efficiently with current. [ABSTRACT FROM AUTHOR]

The Al3FeNd2 single-phase alloy was prepared by melting stoichiometric Al, Fe, and Nd in a nonconsumable arc furnace filled with argon and then homogenizing annealing at a high temperature. The crystal structure of Al3FeNd2 was analyzed by an X-ray powder diffraction technique, Rietveld refinement analysis, and the first-principles simulation calculation method. The results show that the alloy crystallizes in the cubic cell, space group of Fd-3m (no. 227), and the lattice parameters of a = 7.8892 (1) Å, Z = 4, and Dcalc = 5.75 g/cm3. Al3FeNd2 exhibits ferrimagnetic properties at low temperatures and has a Curie temperature (Tc) of 353 K, and its saturation magnetic moment (Ms) is 3.33 μB/f.u. at 2 K. The simulation results also show that Al3FeNd2 is a ferrimagnet with a spontaneous magnetic moment of 4.11 μB/f.u., and it is believed that the spontaneous magnetization of this alloy originates from the electron spin in the Fe(16c)-3d band and Nd(8b)-4f. [ABSTRACT FROM AUTHOR]

Structural, magnetic, and optical properties along with N 2 absorption-desorption features of Sm3+–Dy3+ ions co-substituted BaSr hexaferrite microspheres (HFMSs) engineered through a hydrothermal gel approach were investigated. The microstructural and morphological features were examined by powder X-ray diffraction (XRD), surface area and pore size distribution (BET), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), and transmission electron microscopy (TEM) techniques. Rietveld analysis proved the purity of products. The BET revealed a slight variation in textural characteristics with increasing Sm3+–Dy3+ substitution. The surface area (11–16 m2/g) exhibits a pore volume of ~0.07 cm3/g and average pore size distributions of 26.6 nm. The 300 K and 10 K field-dependent hysteresis loops were registered. Remanent magnetizations (M r) and coercive fields (H C) are in a range of 29.15–34.05 emu/g and 1420–5391 Oe at 300 K, respectively. The estimated saturation magnetizations (M s) vary between 53.22 emu/g and 71.08 emu/g, and magneton numbers (n B) are in a range of 10.51–13.93 μ B. At 10 K, the M r = 35.18–46.83 emu/g, H C = 1487–4760 Oe, M s = 81.82–99.17 emu/g, and n B = 14.83–19.44 μ B , which are greatly higher compared to room temperature. All magnetic parameters exhibit strong ferrimagnetic features of pristine Sr 0 · 5 Ba 0 · 5 Fe 12 O 19 and Dy3+ and Sm3+ co-doped HFMSs at both temperatures. Squareness ratios (SQRs), which are very close to 0.50 assign the single domain uniaxially symmetric structured HFMSs. δ M type of remanence plots was applied to specify the intensity and type of interparticle interactions as a function of the externally magnetic field, H. The Schuster-Kubelka-Munk theory provides to estimate direct energy band gaps (E g). Undoped or co-doped HFMSs have a very narrow magnitude of E g data between 1.795 and 1.865 eV depending on the couple ion concentrations. [ABSTRACT FROM AUTHOR]

Powders of the system (1-x)Bi0.5Na0.5TiO3-xBiFeO3 (x = 0, 0.02, 0.08, 0.10) are synthesized by the combustion reaction method. The crystal structure and the particle size of Bi0.5Na0.5TiO3 are modified by the incorporation of BiFeO3, as can be seen from the infrared spectroscopy and X-ray diffraction results. The inclusion of iron and the increase in the molar percentage of bismuth in the BNT matrix generate new bonds with a different force constant. The structural analysis showed that the addition of BFO to the BNT does not induce any structural phase transition, preserving the rhombohedral symmetry of the Bi0.5Na0.5TiO3 system. The electrical measurements show that the incorporation of iron increases the conductivity of the system generated by an increase in the concentration of oxygen vacancies; alternatively, the addition of 10% of BiFeO3 generates ferrimagnetic behavior reflected in the magnetic hysteresis curves obtained at room temperature. [ABSTRACT FROM AUTHOR]

This review aims to summarize more than 100 years of research on spinel compounds, mainly focusing on the progress in understanding their magnetic, electronic, and polar properties during the last two decades. Over the years, more than 200 different spinels, with the general formula AB 2 X 4 , were identified or synthesized in polycrystalline or single-crystalline form. Many spinel compounds are magnetic insulators or semiconductors; however, a number of spinel-type metals exists including superconductors and some rare examples of d -derived heavy-fermion compounds. In the early days, they gained importance as ferrimagnetic or even ferromagnetic insulators with relatively high saturation magnetization and high ordering temperatures, with magnetite being the first magnetic mineral known to mankind. From a technological point of view, spinel-type ferrites with the combination of high electrical resistance, large magnetization, and high magnetic ordering temperature made them promising candidates for many applications. However, spinels are also known as beautiful gemstones, with the famous "Black Prince's Ruby" in the front centre of the Imperial State Crown. In addition, spinels are important for the earth tectonics, and the detection of magnetite in a Martian meteorite even led to the speculation of life on Mars. However, most importantly in the perspective of this review, spinels played an outstanding role in the development of concepts of magnetism, in testing and verifying the fundamentals of magnetic exchange, in understanding orbital-ordering and charge-ordering phenomena including metal-to-insulator transitions, in developing the concepts of magnetic frustration, in establishing the importance of spin–lattice coupling, and in many other aspects. The still mysterious Verwey transition in magnetite was one of the very first illuminating examples of this complexity, which results from the fact that some ions can exist in different valence states in spinels, even at a given sublattice. In addition, the A -site as well as the B -site cations in the spinel structure form lattices prone to strong frustration effects resulting in exotic ground-state properties. The A -site ions are arranged in a diamond lattice. This bipartite lattice shows highly unusual ground states due to bond-order frustration, with a strength depending on the ratio of inter- to intra-sublattice exchange interactions of the two interpenetrating face-centred cubic lattices. The occurrence of a spiral spin-liquid state in some spinels is an enlightening example. Very recently, even a meron (half-skyrmion) spin structure was identified in MnSc 2 S 4 at moderate external magnetic fields. In case the A -site cation is Jahn–Teller active, additional entanglements of spin and orbital degrees of freedom appear, which can give rise to a spin–orbital liquid or an orbital glass state. In systems with such a strong entanglement, the occurrence of a new class of excitations – spin–orbitons – has been reported. The B -site cations form a pyrochlore lattice, one of the strongest contenders of frustration in three dimensions. A highly degenerate ground state with residual zero-point entropy and short-range spin ordering according to the ice rules is one of the fascinating consequences, which is known already for more than 50 years. At low temperatures, in B -site spinels the occurrence of spin molecules has been reported, strongly coupled spin entities, e.g., hexamers, with accompanying exotic excitations. A spin-driven Jahn–Teller effect is a further possibility to release magnetic frustration. This phenomenon has been tested in detail in a variety of spinel compounds. In addition, in spinels with both cation lattices carrying magnetic moments, competing magnetic exchange interactions become important, yielding ground states like the time-honoured triangular Yafet–Kittel structure. Very recently, it was found that under external magnetic fields this triangular structure evolves into very complex spin orders, which can be mapped on spin super-liquid and spin super-solid phases. In addition, due to magnetic frustration, competing interactions, and coupling to the lattice, very robust magnetization plateaus appear in a variety of spinel compounds as function of an external magnetic field. Furthermore, spinels gained considerable importance in elucidating the complex physics driven by the interplay of spin, charge, orbital, and lattice degrees of freedom in materials with partly filled d shells. This entanglement of the internal degrees of freedom supports an exceptionally rich variety of phase transitions and complex ground states, in many cases with emerging functionalities. It also makes these materials extremely susceptible to temperature, pressure, or external magnetic and electric fields, an important prerequisite to realize technological applications. Finally, yet importantly, there exists a long-standing dispute about the possibility of a polar ground state in spinels, despite their reported overall cubic symmetry. Indeed, recently a number of multiferroic spinels were identified, including multiferroic spin super-liquid and spin super-solid phases. The spinels also belong to the rare examples of multiferroics, where vector chirality alone drives long-range ferroelectric order. In addition, a variety of spinel compounds were investigated up to very high pressures up to 40 GPa and in high magnetic fields up to 100 T, revealing complex (p , T) and (H , T)-phase diagrams. • Ground-breaking concepts in magnetism were developed conceptually using spinel compounds. • Spinels are prototypical examples of strongly frustrated magnets. • Ferroelectricity and multiferroicity in spinels result from very different mechanisms. • Spinels represent outstanding examples of metal-to-insulator transitions and charge order. • Examples of well-established d -derived heavy-fermion​ behaviour. [ABSTRACT FROM AUTHOR]

The evolution of chiral spin structures is studied in ferrimagnetic Ta/Ir/Fe/GdFeCo/Pt multilayers as a function of temperature using scanning electron microscopy with polarization analysis (SEMPA). The GdFeCo ferrimagnet exhibits pure right‐handed Néel‐type domain wall (DW) spin textures over a large temperature range. This indicates the presence of a negative Dzyaloshinskii–Moriya interaction that can originate from both the top Fe/Pt and the Co/Pt interfaces. From measurements of the DW width, as well as complementary magnetic characterization, the exchange stiffness as a function of temperature is ascertained. The exchange stiffness is surprisingly more or less constant, which is explained by theoretical predictions. Beyond single skyrmions, it is identified by direct imaging a pure Néel‐type skyrmionium, which due to the expected vanishing skyrmion Hall angle, is a promising topological spin structure to enable applications by next generation of spintronic devices. [ABSTRACT FROM AUTHOR]