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Yttrium Iron Garnet (YIG) ferrites, characterized by their superior magnetic and dielectric attributes, are instrumental in advancing the development of microwave devices, particularly in enhancing high-frequency performance, integration, and miniaturization. This paper synthesizes YIG ferrite materials with the composition Bi 0.6 Y 1.4-x Ca 1+x Fe 4.5-x V 0.5 Ge x O 12 (x = 0.10 to 0.50, incrementing by 0.10) through the solid-state sintering method. It delves deeply into the mechanism by which Ca2+-Ge4+ ions substitution regulates the magnetic properties of BiV-YIG. The microstructural and magnetic properties of the samples were systematically tested and analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), vibrating sample magnetometry (VSM), and TE106 perturbation method. At a substitution content of x = 0.50, the substitution of Ge4+ ions for the Fe3+ ions at the d-site transforms the material from ferrimagnetic to paramagnetic, and the saturation magnetization of the sample drops to 132.74 G. By calculating the ferromagnetic resonance (FMR) linewidth using the law of approach to saturation, the study elucidates the negative impact of low saturation magnetization on FMR linewidth. The mechanisms proposed in this paper provide theoretical and experimental bases for reducing the FMR linewidth of high dielectric constant Bi-substituted YIG, paving the way for developing high-dielectric, low-loss YIG ferrite materials for microwave devices. [ABSTRACT FROM AUTHOR]

We prepared ultrafine MnCo 2 O 4 particles using a facile sol–gel autocombustion method. The structural and vibrational characterizations confirmed the formation of a pure cubic spinel phase in as-synthesized MnCo 2 O 4 particles. The surface morphology analyses revealed the porous structure with an average particle size of 5 nm and uniform distribution of manganese (Mn), cobalt (Co), and oxygen (O) in the particles. We observed the presence of multiple valence states of Mn and Co, occupying both tetrahedral and octahedral sites, enhancing our insight into the material's electronic properties and structural configuration. Our magnetization studies unveiled a Curie Temperature (T C) of 185 K with ferrimagnetic ordering below T C , resulting in substantial magnetization (9.8 emu/g) and coercivity (3.46 kOe) at 2 K and weak magnetic behavior above T C. This is attributed to the finite size and surface effects. Furthermore, the incorporation of MnCo 2 O 4 nanoparticles and graphene oxide into a polyurethane foam matrix resulted in an excellent sound absorption coefficient of 90 % at 2000 Hz. This outstanding acoustic performance underscores the versatile applications of MnCo 2 O 4 nanoparticles in diverse noise mitigation applications. [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]

We report here the studies of structural and magnetic properties of two equiatomic quaternary Heusler alloys CoCrVZ (Z = Al, Ga). Both the alloys crystallize in LiMgPdSn type crystal structure (space group #216) with B2 (CoCrVAl) and A2 (CoCrVGa) type anti-site disorder between elemental sites. Intended stoichiometry was confirmed from the compositional analysis. The temperature dependence of dc magnetic susceptibility and the low temperature moment values show a nearly compensating ferrimagnetic behaviour at low temperatures for both the alloys. The inverse of dc magnetic susceptibility starts to deviate from the Curie–Weiss law below 220 K and 164 K for the alloys containing Al and Ga respectively. The Arrott plots confirms the absence of long range order down to 2 K. Further analysis of the dc and ac susceptibility shows that the observed behaviour is due to the presence of Griffiths like phase in these alloys. • Systematic study shows that CoCrVZ (Z = Al, Ga) Heusler alloys crystallize in LiMgPdSn type structure (space group #216) with 50% B2 (CoCrVAl) and 25% A2 (CoCrVGa) type anti-site disorders. • The presence of disorder leads to the reduction of magnetic moment and a nearly compensated ferrimagnetic behaviour at low temperatures. • The presence of Griffiths like phase is inferred for both the alloys. [ABSTRACT FROM AUTHOR]

The mean-field approximation based on the Gibbs-Bogoliubov inequality and Monte Carlo simulations based on the Metropolis method in the Blume–Emery–Griffiths model were used to successfully examine a hexagonal Ising nanowire with spin-1. It was found that the model displays fascinating phase diagrams in various planes of interest by using both methods. The investigation of magnetic hysteresis cycles also exhibits interesting properties. The model not only presents first- and second-order phase transition lines, but also the tricritical and isolated critical points, multi-compensation temperatures, and magnetic hysteresis behavior with one to eight cycles. • The mean-field approximation based on the Gibbs-Bogoliubov inequality is applied. • The Monte Carlo simulations based on the Metropolis method is employed. • Spin-1 Blume–Emery–Griffiths model for hexagonal Ising nanowire is investigated. • First- and second-order transitions, tricritical and isolated critical points are found. • Multi-compensation and magnetic hysteresis with one to eight cycles are observed. [ABSTRACT FROM AUTHOR]

This study investigates the magnetocaloric potential of the Al 50 Cr 21-x Mn 17+x Co 12 (x=0, 4, 8 at%) high-entropy alloy (HEA) series using integrated experimental and theoretical approaches. Structural analysis by X-ray diffraction and scanning electron microscopy indicate a dual phase containing B2 and body-centered cubic (BCC) structures. Magnetic characterization shows an approximately linear decrease in saturation magnetization and Curie temperature with increasing Cr content. Curie temperatures calculated by Monte Carlo simulations suggest that the measured magnetic properties originate from the B2 phase rather than the BCC phase. The enhanced magnetocaloric effect with decreasing Cr content highlights the attractiveness of HEAs in magnetocaloric applications. • Al 50 Cr 21-x Mn 17+x Co 12 (x=0, 4, 8 at%) high-entropy alloys were prepared by arc melting. • The phase and chemical composition analysis indicates a dual phase containing B2 and BCC structures. • Calculated T C s suggest that the measured magnetic properties originate from the B2 phase rather than the BCC phase. • Tunable TC and magnetization with decreasing Cr were confirmed through measurement of TC and hysteresis loops. • The magnetocaloric effect was quantified by measuring the adiabatic temperature change and magnetic entropy change. [ABSTRACT FROM AUTHOR]

This work utilizes a multi-scale computational approach combining first-principles density functional theory (DFT) and Monte Carlo statistical simulations to provide fundamental insights into the impacts of vanadium (V) doping on the structural, electronic, magnetic, and thermodynamic properties of wurtzite zinc sulfide (ZnS). 2 × 2 × 2 ZnS supercells with controlled V doping concentrations from 12.5%–25% substituting zinc sites were constructed. The introduction of V dopants induces systematic expansions in lattice parameters and cell volume, attributed to the larger ionic radius of V 2 + than Zn 2 + , while the average compressibility shows minimal variation. However, V incorporation is found to soften ZnS by over 15% at higher dopant contents, increasing compliance and anisotropy. Stable ferromagnetic spin couplings emerge, mediated by host carriers without precipitating V secondary phases. The band structure develops half-metallic electronic properties with the lifting of spin degeneracy and preferential spin-up band metallicity induced by V-3d and S-3p hybridization effects. This results in 100% spin polarization at the Fermi level. Monte Carlo simulations based on a tight-binding Hamiltonian constructed from maximally localized Wannier functions to accurately calculate the exchange interactions between V spins successfully reproduce the magnetic phase transition behavior. The results confirm high Curie temperatures exceeding 300 K at 25% V, attributable to the significant strengthening of short-range ferromagnetic couplings over antiferromagnetic interactions. The integrated computational approach provides fundamental insights into the microscopic origin of carrier-mediated ferromagnetism in V-doped wurtzite ZnS dilute magnetic semiconductors. The systematic first-principles calculations and statistical mechanics modeling establish clear structure–property relationships linking V doping configurations and concentrations to tuned mechanical response, enhanced stability, electronic structure modifications, spin polarization, and magnetic ordering temperatures in ZnS. The results present design pathways and predictive capabilities to guide experimental efforts toward emerging high-performance magnetic materials for spintronic technologies. [Display omitted] [ABSTRACT FROM AUTHOR]

Polycrystalline samples of DyCo 9 Si 4 with the tetragonal LaFe 9 Si 4 -type structure have been synthesized by arc melting and high-temperature annealing. Results of the magnetization M and specific heat C p measurements show the existence of two magnetic anomalies at T C = 40 K and T m = 20 K. The transition at T C = 40 K is attributed to the ferromagnetic transition of the Co sublattice. The magnetic moments of Dy3+ appear to align gradually below T C , and almost fixed below T m , at which a broad maximum in C p has been observed. Field-dependent M at T = 2 K up to H = 7 T suggested that the magnetic moment of Dy3+ is coupled antiferromagnetically with those of Co, forming a ferrimagnetic structure. Magnetization measurements up to 50 T at low temperatures using a pulse magnet demonstrated a spin-flip transition around H = 20 T, above which the magnetic moments of Co and Dy are in parallel. The spin-flip transition becomes broad with increasing temperature but still remains at T C = 40 K, indicating a strong antiparallel coupling between Co and Dy moments even in the paramagnetic state. The magnetocaloric effect was evaluated from C p and M , and also from the sample-temperature variation in the quasi-adiabatic process with the pulsed magnetic field. The maximum entropy change for the field change from 5 to 0 T was observed at around T = T m with the value Δ S = 5 J/kg K. The maximum temperature of Δ S shifts to higher temperatures in high magnetic fields, resulting in the large value of Δ S = 24 J/kg K at T ∼ T C by the field change from 50 to 0 T. The present results demonstrate that the pulsed-field measurement is a powerful method to evaluate the magnetocaloric effect of materials. ● Physical properties of DyCo 9 Si 4 are reported for the first time. ● Step-like increase of the magnetization curve is observed at low temperature. ● Antiparallel coupling of Dy/Co magnetic moments remains in the paramagnetic state. ● Pulsed field measurement enables a quick and reliable magnetocaloric evaluation. ● Large magnetocaloric effect of 24 J/kg K is observed at T = 40 K. [ABSTRACT FROM AUTHOR]

Magnetic properties of multicomponent alloys depend sensitively on the degree of atomic order on the different crystallographic sites. Here we report the contrast between the magnetic properties of bulk and thin-film samples of the Heusler alloy V 2 FeAl. Arc-melted bulk ingots show no site preference of the elements (A2 structure), whereas magnetron-sputtered thin-film samples display a degree of atomic ordering with a tendency towards XA-type order. Electronic structure calculations favour ferrimagnetic XA-type order, and the effect of different pairwise atomic disorder on the element specific and net magnetic moments are evaluated to reproduce experimental observations. XA-type thin-films with iron moment of 1.24 μ B determined by X-ray magnetic circular dichroism are in agreement with calculation, but the measured net moment of 1.0 μ B per formula unit and average vanadium moment are smaller than expected from calculations. The measured Curie temperature is approximately 500 K. Films with a higher degree of disorder have a lower T C , close to 300 K, with a net moment of only 0.1 μ B at low temperature. The large calculated vanadium moments are destroyed by partial disorder on 4 d vanadium sites. By contrast, the arc-melted and annealed bulk alloy with a fully-disordered A2 structure shows no spontaneous magnetization at any temperature; it is a Pauli paramagnet with dimensionless susceptibility χ v = 2.95 × 10-4. [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]

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]

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]

• 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]