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An upsurge of research activities is conducted to assess the magnetic properties of graphene nanoribbons with a keen focus on spintronic applications. The critical and compensation characteristics of mixed spin-3/2 and spin-1/2 Ising nanoribbons (Nrbs) with rectangular and hexagonal shapes under a transverse field are explored employing the finite cluster approximation. In the absence of transverse fields, only the rectangular Nrb, may exhibit one or two compensation points. This compensation persists under a transverse field Ωσ that exclusively affects the spin-1/2 of the σ-sublattice, where the order is destroyed at some Jσ-dependent critical transverse fields at T = 0. Interestingly, the insertion of a transverse field ΩS acting only on the S-sublattice, demonstrates that the order cannot be destroyed at low temperatures, with the possibility of reentrance as well as tricritical behaviors for rectangular Nrb. Finally, all these behaviors have been confirmed through an analysis of the magnetizations. [ABSTRACT FROM AUTHOR]

Polycrystalline [(0.5) Bi0.5Na0.5TiO3-(0.5) LaFeO3] multiferroic composite is prepared by using the solid-state reaction method. The crystal structure of both phases is characterized by using the X-ray diffraction method (XRD) and confirms the presence of rhombohedral (i.e., bismuth sodium titanate) and orthorhombic (i.e., lanthanum ferrite) phases in the composite. The microstructure of the composite is analyzed using field emission scanning electron microscopy (FESEM). The crystal structure is further studied with Raman spectroscopy. The present composite exhibits ferroelectric and ferrimagnetic-like properties, revealing its multiferroic behavior. Furthermore, the impedance analysis of the composite shows the negative temperature coefficient of resistance behavior. The present study describes the structural and physical properties of the possible lead-free multiferroic composite. [ABSTRACT FROM AUTHOR]

The magnetic and magnetocaloric properties of a zigzag triangular nano-graphene with Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange interactions in the mixed 1 and 3/2 spins are studied with the aid of the Monte Carlo investigations. The thermal magnetizations and the magnetic susceptibilities are considered. The phase diagram of the system and the variation of magnetizations with crystal field are established. The magnetic entropy for different external magnetic fields has been also sketched. The dependence of the field on the relative cooling power (RCP) of the system is found; the specific heat displacement of the system is displayed. Also, the adiabatic temperature of the system has been defined. Lastly, the magnetic hysteresis cycle with mixed spins S = 1 and σ = 3/2 for several different parameters is obtained. It can be observed that the values obtained for RCP rise with increasing external magnetic field and reduce with increasing N for constant parameters. The critical temperature values are also affected by the increasing number of non-magnetic layers. In addition, the effect of the RKKY interaction decreases as 1/N2. As a consequence, the system becomes rapidly out of order as the number of non-magnetic layers N is increased. [ABSTRACT FROM AUTHOR]

Ferrimagnetic substance-based Zn0.4Alx@Ni0.6-xFe2O4 (x = 0.0, 0.02, 0.04, 0.06, and 0.08) nanocomposite system was prepared by two-step seed implant polyacrylamide sol–gel method. The structural and frequency-dependent sensitivity of soft magnetic core materials was optimized by the substitution of Al3+ ions. The nonstoichiometric of the constituents has caused by the consisting of a small amount of two secondary phases (Zn-oxide and Zn-Al-oxide) which have been detected from the short intensity of XRD peaks using the Rietveld refinement program. The replacement of Ni2+ ions by Al3+ ions plays a major role in the rearrangements of Ni2+ and Fe3+ ions between octahedral A and tetrahedral B sites and is lead to optimization of magnetic behavior and impedance response. The maximum coercivity (493.73 Oe) and saturation magnetization (58.26 emu/g) observed at x = 0.08 and 0.02, respectively. The resulting magnetic permeability shows that the value is enhanced up to 6.411% within 1 Oe of applied magnetic field. In addition, the impedance value reaches maximum of 1.49 × 105 Ω at sample x = 0.02, reduced to minimum of 4.8 × 103 Ω at x = 0.08. The magnetic sensitivity of ZnAl-NiFe2O4-based core materials at room temperature under 0–5 log f with 0.01 T magnetic field has also been investigated. The magneto-impedance results can be used to substantiate the increase in sensitivity due to the rearrangement of Ni2+ and Fe3+ ions. [ABSTRACT FROM AUTHOR]

The current study examines the structural, surface morphology, electrical, optical, and magnetic properties of [Co(1-x)Scx][Cr2][O4] (x = 0, 0.01, 0.03, 0.05, 0.07) prepared by combustion method. XRD (X-ray diffraction) and Raman spectra were utilized to confirm phase and structural. SEM (scanning electron microscopy) micrographs were utilized for the analysis of the surface morphology. AC conductivity and dielectric characteristics were utilized to investigate the electrical properties. UV–Vis DRS (UV–Vis diffuse reflectance spectroscopy) was used to investigate the optical characteristics. The development of spinel cubic structure is confirmed by XRD. The hopping lengths increase as the Sc3+ ion concentration rises. The extremely porous nature may be seen in all SEM images. The Koop's phenomenological theory and hopping mechanism were utilized to explain dielectric properties. At higher frequencies, all samples have good AC conductivity and a low dielectric loss tangent. Optical experiments were conducted using a UV–Visible diffuse reflectance spectrometer to assess the energy gap and absorbance bands. The decrease in the energy gap as Sc3+ concentration rises could be explained by an increase in the lattice parameter due to an increase in Sc3+ concentration. The dc-susceptibility study reveals two magnetic transitions such ferrimagnetic (FIM) order transition below Curie temperature (Tc) and spiral spin order transition at spiral transition temperature (Ts). The scandium-doped [Co][Cr2][O4] samples show negative magnetization below compensation temperature (Tcomp). The obtained results from M-H loop at 25 K, 95 K, and 300 K agree well with the magnetic transitions obtained from the temperature-dependent susceptibility study. [ABSTRACT FROM AUTHOR]

We present a study on the magnetic properties and magnetocaloric effect (MCE) in R3Co11B4, where R = Pr, Nd, Tb, Dy, and Ho. The two-sublattice model is used for calculating magnetization, magnetic heat capacity, isothermal entropy change ∆Sm, and adiabatic temperature change ∆Tad, for different magnetic field changes ∆H = 1.5, 3, and 5 T and at temperatures up to 600 K. Direct and inverse MCE are shown to take place in the ferrimagnetic compounds with R = Tb, Dy, and Ho. The maximum isothermal magnetic entropy change and maximum adiabatic temperature change have been calculated for ferromagnetic Nd3Co11B4 compound to be 1.85 J/K mol and 6.5 K at Tc = 432 K, for a field change ∆H = 5 T. The relative cooling power (RCP) is in the 44–161 J/mol range for the same field change. Also, the type of phase transition is investigated in the light of Arrott plots, universal curves, and the features of the temperature and field dependences of the magnetization, heat capacity, entropy, and the magnetocaloric properties. Those features confirm that the transition at the Curie temperature of these compounds is of the second order. [ABSTRACT FROM AUTHOR]

Using Monte Carlo simulations under the Metropolis algorithm, the magnetic properties of a Mixed Spins (3/2, 1) cubic lattice modeled by mixed spin Ising model have been investigated. First, we discuss the ground state phase diagrams at zero temperature corresponding to different parameters of the model. Then, by choosing ferrimagnetic phases found in the obtained phase diagrams, we analyze the magnetization and compensation behaviors in our system. Striking results have been found; especially, the competition between exchange coupling interactions generates a critical temperature T C and a compensation temperature T comp with T comp < T C . Moreover, the presence of crystal and external magnetic fields leads to the appearance of a second compensation temperature with T c o m p 1 < T c o m p 2 ≪ T C . [ABSTRACT FROM AUTHOR]

We present a study on the magnetic properties and magnetocaloric effect (MCE) in R3Co11B4, where R = Pr, Nd, Tb, Dy, and Ho. The two-sublattice model is used for calculating magnetization, magnetic heat capacity, isothermal entropy change ∆Sm, and adiabatic temperature change ∆Tad, for different magnetic field changes ∆H = 1.5, 3, and 5 T and at temperatures up to 600 K. Direct and inverse MCE are shown to take place in the ferrimagnetic compounds with R = Tb, Dy, and Ho. The maximum isothermal magnetic entropy change and maximum adiabatic temperature change have been calculated for ferromagnetic Nd3Co11B4 compound to be 1.85 J/K mol and 6.5 K at Tc = 432 K, for a field change ∆H = 5 T. The relative cooling power (RCP) is in the 44–161 J/mol range for the same field change. Also, the type of phase transition is investigated in the light of Arrott plots, universal curves, and the features of the temperature and field dependences of the magnetization, heat capacity, entropy, and the magnetocaloric properties. Those features confirm that the transition at the Curie temperature of these compounds is of the second order. [ABSTRACT FROM AUTHOR]

The ferri-ferro-ferrimagnetic quaternary alloy described in the form as A B p C q D r consisting of spins S i A = 1 , S i B = 1 / 2 , S j C = 3 / 2 and S j D = 5 / 2 , respectively, is investigated in detail by the mean field theory (MFT) based on the Bogoliubov inequality for the free energy with the coordination number z = 3 . The phase diagrams are mapped on the planes of (R 1 = J AC / | J AB | , k T c / | J AB |) , (R 2 = | J AD | / | J AB | , k T c / | J AB |) , (p , k T c / | J AB |) and (r , k T c / | J AB |) by studying the thermal variations of the order parameters, i.e., the magnetizations. In addition to the critical temperatures, either second- or first-order phase transition temperatures without distinction, shown by the model, it also exhibits a single or a double compensation temperatures for appropriate values of the system parameters. The Monte Carlo (MC) simulations are also used to confirm the existence of the multi-compensation behaviors in the model as found by the MFT approach by examining the thermal variations of the total magnetization of the system. Our obtained results are compared to those reported in the literature, and reliable agreements are observed. [ABSTRACT FROM AUTHOR]

The magnetic properties of the mixed spin − 1/2 and spin − 1 Ising ferrimagnetic nanotube with a hexagonal lattice in the presence of the crystal field are investigated by means of the finite cluster approximation. We examine the effects of the crystal field, the surface shell, and core coupling parameters where the main attention has been paid to study the magnetizations and also the phase diagrams for both transition and compensation temperatures. In the absence of the crystal field, the compensation behavior exists only in a limited range of surface shell and core couplings. By introducing a crystal field, the compensation behavior is maintained and the tricritical behavior occurs depending on the strength of surface shell coupling. [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]

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]

We have investigated the structural and magnetic properties of Mn2Ge, using the projector augmented wave (PAW) method within the generalized gradient approximation (GGA). We have observed that the crystal symmetry for Mn2Ge is more likely to be tetragonal like Cu2Sb, rather than the hexagonal symmetry of Ni2In. Different magnetic ordering is assumed for Mn2Ge, based on that the electronic structure calculations are performed for Mn2Ge with antiferromagnetic (AFM), ferrimagnetic (FIM) spin ordering. In the most favorable ground state of Mn2Ge, nearest Mn (I) and Mn (II) are coupled ferromagnetically. The magnetic moments on the Mn(I) and Mn(II) are found to be varying based on their magnetic ordering. When ordering is ferromagnetic between Mn(I) and Mn(II), the magnetic moment on Mn(I) is large and in all other cases Mn(II) has larger magnetic moment. Easy flipping of spins has been observed. [ABSTRACT FROM AUTHOR]

A new ternary compound, Al2Fe3Nd, was prepared via arc melting using a non-consumable tungsten electrode under an argon atmosphere with subsequent annealing at 923 K for 30 days. Its crystal structure was determined using the Rietveld refinement of powder X-ray diffraction data. The results show that Al2Fe3Nd has a hexagonal structure in a space group of P6/mmm (No. 191). It is isostructural with the Al2.5Ni2.5Y compound. It has lattice parameters of a = 8.8625(3) Ǻ and c = 4.1475(2) Ǻ with a calculated density Dcalc = 6.460 g/cm3. The residual factors converge to Rp = 0.0946 and Rwp = 0.1214. In the temperature range of 2–500 K, magnetic susceptibility has been measured. The magnetic susceptibility of Al2Fe3Nd follows the Curie–Weiss law in the temperature range of 410–500 K. The effective magnetic moment μeff and paramagnetic Curie temperature θP were estimated to be 8.59 μB and 399.8 K, respectively. The saturation magnetic moment and magnetic hysteresis loop for the compound were measured under room- and low-temperature conditions. The measurements indicate that the saturation magnetization moment declines with increasing temperature, and the compound is ferrimagnetic in the analytical temperature range of 2–300 K. [ABSTRACT FROM AUTHOR]

Compositions of ferrimagnetic NiSmxFe2−xO4 (0.00 ≤ x ≤ 0.25) ceramics were synthesized by the self-propagating sol-gel autocombustion method. Structural information was found using X-ray diffraction. It reveals that all the ceramics possess cubic symmetry of spinel ferrite with a small amount of orthoferrite phase SmFeO3, which is a ferroelectric material. The amount of phases and lattice parameter were determined by the Rietveld refinement method using the Fullprof suite software. As doping concentration increases, the secondary phase fraction of the ferroelectric SmFeO3 also increases. Due to the increase of the ferroelectric phase in NiFe2O4, the electrical properties of doped samples also modify. To know this modification, the electrical properties of these samples have been investigated. The room temperature dielectric and complex impedance analysis have been measured in the frequency range of 1–106 Hz. The dielectric behavior for x = 0.05 concentration (NiSm0.05Fe1.95O4) has a maximum dielectric constant value with a minimal loss tangent. Cole-Cole plot brings out the role of grain and grain boundaries in the bulk. Using impedance study, the resistance and capacitance of grain and grain boundaries have been determined. The ferroelectric behavior has been performed through the P-E (polarization versus electric field) and J-E (leakage current versus electric field) curves at room temperature. [ABSTRACT FROM AUTHOR]

This article gives a review on some important experimental studies on the magnetization curves using different theoretical models. Applications of the law of approach to saturation magnetization and Langevin function to various kinds of magnetic materials belonging to different groups such as ferromagnetic, ferrimagnetic, antiferromagnetic, superparamagnetic materials at various experimental conditions, applied field ranges, and their dependencies on the applied field are collectively reviewed. Extraction of important magnetic parameters by fitting magnetization data with suitable models and their variation with composition, morphologies, size etc. along with the strategies adopted are also discussed. The purpose and outcomes of such studies along with future scope are also highlighted in this review. [ABSTRACT FROM AUTHOR]

In this manuscript, we study the structural, electronic, and magnetic properties of the equiatomic quaternary Heusler alloy ZnCdRhMn in the framework of the first-principle calculations and Monte Carlo simulations. In fact, we have investigated the structural, the magnetic, and the electronic properties of the Zn-based equiatomic quaternary Heusler alloy ZnCdRhMn using the ab initio method in the bases on the GGA approximation. On the other hand, the critical behavior of the equiatomic quaternary Heusler alloy ZnCdRhMn has been outlined by the Monte Carlo simulations. For this end, we apply the Metropolis algorithm. The objective of this work is to improve the competition between the austenitic and martensitic phases on the existence of magnetic and electronic properties of this alloy. The half-metallic behavior is only improved for the austenitic structure and 100% of spin polarization has been found. Moreover, a high curie temperature is found for this alloy for the austenitic phase. We can conclude that the austenitic structure of this alloy is useful for the spintronic device applications. [ABSTRACT FROM AUTHOR]

We have employed first-principles calculations of density functional theory (DFT) with GGA and GGA+U exchange correlation to study structural, magnetic, and electronic properties of chromium nitride (CrN) in the rock salt (NaCl) structures. The obtained data from DFT calculations is used as an input in high-temperature series expansions (HTSEs) combined with the Padé approximants (PA) method and Monte Carlo simulation (MC) for the Ising model to investigate the magnetic properties of CrN. The obtained results show that CrN is more stable in the antiferromagnetic order, and undergoes structural and magnetic transitions from an antiferromagnetic NaCl structure to a nonmagnetic Pnma phase at 201 GPa. The density of states (DOS) with GGA approach shows that CrN has a metallic behavior in both FM and AFM configurations whereas with GGA+U CrN is semiconductor in AFM and half-metallic in FM order. The Neel temperature (TN) obtained by HTSE and MC is in agreement with available experimental data. [ABSTRACT FROM AUTHOR]

The morphology, crystal structure, and thermal and magnetic properties of BaFe11.7In0.3O19 compound have been investigated. As a result of the structure investigations performed by x-ray diffraction method, it was determined that the crystal structure of this compound has hexagonal symmetry with P63mmc space symmetry at normal condition and room temperature. Temperature dependence of specific magnetic moment of BaFe11.9In0.1O19 compound has been established using magnetometry method. It was determined that ferrimagnetic-paramagnetic phase transition occurs at TC ~ 410 °C temperature. Ferrimagnetic-paramagnetic phase transition was studied from DSC spectrum and thermodynamical parameters of phase transition were determined. Thermophysical studies on the BaFe11.9In0.3O19 compound have shown that thermal transitions occur by a complex mechanism. There were decomposition parts determined from the kinetics of DSC spectra: T ≤ 50 °C rapid decomposition, T ≤ 430 °C slow decomposition, and T ≤ 830 °C rapid decomposition parts. [ABSTRACT FROM AUTHOR]

Here, we report successful single crystal growth of new possible magnetic topological insulator (MTI) FeBi2Te4 by a self-flux method via a vacuum encapsulation process. The detailed Rietveld analysis of powder XRD data shows the as-grown MTI crystal to be mainly dominated by the FeBi2Te4 phase along with minority phases of Bi2Te3 and FeTe. Scanning electron microscope (SEM) image shows the morphology of as-grown MTI single crystal to be of layered type laminar structure. Raman spectroscopy of the crystal exhibited three distinct phonon modes at 65, 110, and 132 cm−1 along with two split secondary modes at 90, and 144 cm−1. The secondary split modes are the result of FeTe intercalation in the Bi2Te3 unit cell. Magnetoresistance (MR%) measurement has been performed at different temperatures, i.e., 200 K, 20 K, and 2 K in applied magnetic fields up to ± 12 Tesla, which showed very low MR in comparison with pure Bi2Te3 crystal. Temperature dependence of DC magnetization measurements shows the FeBi2Te4 crystal to be mainly of ferromagnetic (FM) or ferrimagnetic nature above 295 K, albeit a secondary weak magnetic transition is seen at 54–46 K as well. Detailed isothermal magnetization (MH) results showed that the FM saturation moment at 295 K is 0.00213 emu/g, which is nearly invariant until 400 K. In summary, we had grown an MTI FeBi2Te4 single crystal, which may be a possible entrant for the quantum anomalous Hall (QAH) effect at room temperature or above. [ABSTRACT FROM AUTHOR]

The structural, electronic, and magnetic properties of the NiFe2O4 compound are studied using several theoretical methods such as first-principle calculations based on density functional theory (DFT), Monte Carlo simulations, and mean-field theory. The exchange-correlation potential was resolved by generalized gradient approximation (GGA) that underestimates the band gap energy value; therefore, this later needed to be corrected using the GGA + U approximation. The gap energy value (1.10 eV) obtained by the theoretical method is in good agreement with experimental value (0.99 eV). Using ab initio calculations, the exchange-coupling interactions are J1 = 40.665 meV, J2 = 45.382 meV, and J3 = −3.260 meV. Moreover, the semiconductor NiFe2O4 compound exhibits a second-order ferromagnetic-paramagnetic phase transition around TC = 844 K; this value is in good agreement with experimental results. The total magnetization, susceptibility, and specific heat of this compound are investigated. [ABSTRACT FROM AUTHOR]

In this work, the phase transitions, for a molecular-based magnet, are examined using mean field method (MFM). The longitudinal magnetizations can be achieved by minimizing the free energy is an interesting function for locating and induction of spin compensation temperatures as well. By applying Blume-Capel (BC) configuration to a system consisting of two sublattices for a mixed spin-3/2 and spin-7/2on a square lattice in the anisotropies plane, the ground-state phase diagram of this system has been built. On principles of Bogoliubov inequality (BI) of the free energy, it has been investigated the spin compensation phenomena. In particular, characteristic ferrimagnetic features have been shown depending on an unequal crystal field parameters (DA, DB<-1.0) applied on the A−sites and B−sites, respectively. [ABSTRACT FROM AUTHOR]

In this paper, we have studied the structural, electronic, and magnetic properties of the cubic perovskite system Mn4N using the first principles calculations based on density functional theory (DFT) with the generalized gradient approximation (GGA). The obtained data from DFT calculations are used as input data in Monte Carlo simulation with a mixed spin-5/2 and 1 Ising model to calculate the magnetic properties of this compound, such as the total, partial thermal magnetization, and the critical temperatures (TC). The obtained results show that Mn4N has a ferrimagnetic structure with two different sites of Mn in the lattice and presents a metallic behavior. The obtained TC is in good agreement with experimental results. [ABSTRACT FROM AUTHOR]

The phase transitions of two mixed-spin (1/2,1) Ising nanoparticles with n = 4.0 and n = 6.0 are investigated by using the effective-field theory with correlations (EFT). The spin-1 atom with a single-ion anisotropy is decorated at the center of regular n-polygon (or nanoparticle with a value of n) and the spin-1/2 n atoms are put at the perimeter n sites. The phase transition in the nanoparticle with n = 6.0 is rather different from that in the nanoparticle with n = 4.0. It is shown that the number of n plays just like the coordination number z in the bulk mixed-spin Ising systems: the hexagonal nanoparticle with n = 6.0 has exhibited the first-order transition and the tricritical behavior, although the tetragonal nanoparticle with n = 3.0 did not show such behaviors, depending on the values of exchange interactions. [ABSTRACT FROM AUTHOR]

Using first-principles calculations, we predicted the half-metallic, mechanical, and acoustic properties of novel CuHg2Ti-type Mn2LiZ (Z=As, Sb) compounds. It was found that Mn2LiAs and Mn2LiSb are half-metallic ferrimagnetic compounds with gaps in the minority-spin direction of 1.094 and 1.099 eV in equilibrium state, respectively, and have an integer total magnetic moments of 2.000 μB per formula unit for adherence to the Slater-Pauling rule. It was also found that Mn2LiAs and Mn2LiSb are mechanically stable, brittle, and elastically anisotropic, and Mn2LiAs has more brittleness, more significant anisotropy, and higher Debye temperature than Mn2LiSb. [ABSTRACT FROM AUTHOR]

Critical behavior and magnetic properties of La0.67Sr0.33MnO3 (symbolized as LS33MO) have been studied by means of Monte Carlo simulation (MCS). By using the heat-bath algorithm and the Ising model up to third nearest neighbor exchange interactions, we have computed the magnetic and magneto-caloric properties. The effects of the temperature (T) and the external magnetic field (h) on the magnetic behavior of LS33MO have been discussed. The results demonstrate that the Curie temperature (TC) is close to the experimental value. The magnetic entropy shows a maximum value around TC which increases linearly with the rise of the external field h. For h = 5T, the maximum entropy (∆ S m max ) is about 3.67 J K−1 kg−1 which is in good agreement with the experimental results. The relative cooling power (RCP) has been estimated and it has been found that it increases with respect to the external field. The predicted critical behavior has been studied by isothermal magnetization of LS33MO nanoparticle compound. The critical exponents (Crt.Exps) are determined by various approaches, such as the modified Arrott plot (AP) and critical isotherm ways. Therefore, the Crt.Exp values obtained by different techniques are β = 0.306, γ = 1.178, and δ = 4.025 respectively. The trustworthiness of the values of the Crt.Exp was approved by the Widom scaling equation and the universal scaling hypothesis. [ABSTRACT FROM AUTHOR]

In the presence of the crystal field D/JCore and the external magnetic field h/JCore, using the Monte Carlo (MC) simulation based on the heat bath algorithm and the effective field theory (EFT), the triangular mixed spin nanowire model consisting of a spin-(1/2) core which is encircled by a spin-1 ferrimagnetic surface shell is studied. We have studied the special effects of the core surface and crystal field on the critical and compensation temperatures. Several properties, such as the magnetization, hysteresis behaviors, coercive field, and remanent magnetizations are studied. For the appropriate values of the system parameters, the compensation point and multi-loops are found PACS 05.50. + q; 77.80. Bh. [ABSTRACT FROM AUTHOR]

The XY model has been used in a centered rectangular lattice structure consists of two sub-lattices of spin 1–1/2 with different ferromagnetic couplings on each lattice and anti-ferromagnetic interaction between the two sub-lattices. Utilizing the Monte Carlo simulation, we have studied the energy per site, the specific heat, the total magnetization, the initial susceptibility, and hysteresis effects. Our results revealed that existences of two peaks on the specific heat and a single loop historic behavior. The Binder cumulant and initial susceptibility both confirmed the existence of critical temperature where the system possesses a phase transition to paramagnetism. Such behaviors are monitoring by the different coupling constants adopted in this study. [ABSTRACT FROM AUTHOR]

Magnetic properties of antiferromagnetic nanoparticles are not as straight forward as for ferromagnetic and ferrimagnetic nanoparticles. We analyzed the data of antiferromagnetic six-line ferrihydrite nanoparticles by considering distribution in particle magnetic moment. The fit of magnetization data, using non-linear least square fit procedure, considering Langevin function with and without distribution in particle magnetic moment, is presented. Magnetization of the system is measured as function of temperature and applied magnetic field. [ABSTRACT FROM AUTHOR]

We have investigated the magnetic phase transitions and compensation points in a series of molecular-based magnetic material using the Oguchi approximation. The considered system is a mixed spin-3/2 and spin-5/2 Blume-Capel Ising ferrimagnet with different single-ion anisotropies on both simple cubic and face-centered cubic lattices respectively. The minimized free energy of the mixed spin ferrimagnetic model has been used to extrapolate the equilibrium magnetizations and the compensation temperatures. The crystal field dependence of multicompensation phenomenon has mainly been investigated. The present study produces new results regarding the face-centered cubic lattice, which encourages future experimental works. [ABSTRACT FROM AUTHOR]

Magnetism, electronic structure, elastic and thermal properties of Mn2YAl (with Y = Cr, V) have been investigated. The optimized lattice parameters, bulk modulus, and cohesive energy have been obtained. These alloys have the ferrimagnetic state as the most stable magnetic configuration, since the calculations showed a strong Mn-V antiferromagnetic coupling leading to the ferromagnetism of the Mn sublattices. A small and itinerant magnetic moment of Mn at the A site is found, which is antiparallel to the moment of Y at the B position in Mn2YAl (with Y = Cr, V) compounds. The calculated total spin moments are integral values and increase from − 2 μB/f.u. for Mn2VAl to – 1 μB/f.u. for Mn2CrAl with increasing the number of valence electrons. Band structure and total and partial density of states could be calculated via applying the modified Becke Johnson approximation (mBJ). Based on these results, Mn2YAl (with Y = Cr, V) are half-metallic ferrimagnets with the energy gap lies in the majority spin direction and a high-spin polarization (100%). The main difference between these two compounds is that the band gap is increased by 48% (0.210 eV for Mn2CrAl and 0.401 eV Mn2VAl). Elastic anisotropies, brittleness, and thermodynamic properties are determined for the Mn2YAl (with Y = Cr, V). The slight difference in the spatial distributions of Young's moduli of Mn2YAl (with Y = Cr, V) reflects the small differences for the elastic anisotropies of the alloys under consideration. The mechanical stability of Mn2YAl (with Y = Cr, V) alloys are studied based on the elastic constants. The thermal properties are studied and investigated using the quasi-harmonic model, in addition, the temperature effect on heat capacities at constant pressure and volume, entropy, and thermal expansion are analyzed and discussed. [ABSTRACT FROM AUTHOR]

Single phase MFeCrO4 (M = Co/Ni) nanosized samples are prepared by solution combustion method using glycine as fuel. Lattice parameter obtained after Rietveld refinement of the powder x-ray diffraction pattern of CoCrFeO4 and NiCrFeO4 samples are 8.374 and 8.325 Å and corresponding crystallite sizes are 40 and 27 nm, respectively. FTIR spectra of both samples show tetrahedral and octahedral metal oxygen bond stretching peaks at 596 and 488 cm−1, indicating spinel phase formation. DC magnetisation study indicates that both samples are ferrimagnetic at room temperature, with CoCrFeO4 having a higher value of saturation magnetisation. Mössbauer spectra indicate the presence of magnetic relaxation in the samples. Also, the strength of interaction with nearest neighbour Fe3+ cations is higher in NiCrFeO4. [ABSTRACT FROM AUTHOR]

The effects of single-ion anisotropies and an external magnetic field on the magnetization of the mixed-spin (7/2, 3/2) ferrimagnetic Ising system are investigated within Monte Carlo simulation. Under certain values of the physical parameters, multiple hysteresis loop behaviors such as double, triple, and quintuple hysteresis cycles have been observed. Particularly, the superparamagnetic phase has been shown. The ground-state phase diagrams are presented. [ABSTRACT FROM AUTHOR]

Variations of Curie temperature and strength of magnetic phases with sintering temperature and Ni concentration is investigated in the present work. The AC susceptibility studies show a decrease in Curie temperature (TC) with an increase in Ni concentration in the samples. Comparison of Curie temperatures with the reported results reveals that samples in the present work show higher TC enabling high thermal stability. The Mössbauer spectra of nano- and sintered Ni-Zn ferrite samples were recorded at room temperature to monitor the local environment around Fe cations through Mössbauer hyperfine parameters as a function of composition and sintering temperatures. The increase in sharpness of the Mössbauer sextet with an increase in Ni concentration and sintering temperature corroborate improvement in homogeneity and ferrimagnetic ordering. The results of hyperfine parameters offer the possibility of having close view on configuring Curie temperature through monitoring hyperfine field by altering sintering temperature and/or Ni concentration. As the temperature dependence of magnetic and magnetoelastic properties is strongly influenced by the Curie temperature, the successful possible configuration of Curie temperature in the present work can be further investigated for desired sensor applications. [ABSTRACT FROM AUTHOR]

By means of the Monte Carlo method, we have simulated the mixed-spin-1/2 and spin-2 Ising ferrimagnetic system on a honeycomb lattice. We studied the variations of the magnetization as functions of the crystal field and the temperature and obtained the phase diagram of the system for various crystal field values. We have found that the system cannot display a point of compensation if we consider only nearest-neighbor interactions and the crystal field effect. Also, the tricritical point does not exist. To the best of our knowledge, this system has never been studied using the Monte Carlo method. [ABSTRACT FROM AUTHOR]

The magnetic properties of Ising spin-2 model on recursive p-polygonal structures are studied using Monte Carlo simulations. The thermal magnetization and magnetic susceptibility of recursive 1-, 2-, 3-, and 4-polygonal structures have been terminated. The variation of magnetization and magnetic susceptibility of recursive 2-polygonal structures for several external magnetic field and the variation of magnetization and magnetic susceptibility versus the crystal field and temperatures of recursive 1-, 2-, 3-, and 4-polygonal structures are given. Finally, the magnetic hysteresis cycle of recursive 1-, 2-, 3-, and 4-polygonal structures are obtained and for different temperatures with 2-polygonal structures. It is shown that the reduced transition temperature increases with increasing the p-polygonal structures and decreases with increasing the absolute value of crystal field. The magnetic coercive field increases with increasing the p-polygonal structures and decreases with increasing the temperature values. The superparamagnetism behavior is observed in our system at around reduced transition temperature. [ABSTRACT FROM AUTHOR]

In the present work, a self-consistent ab initio calculation using the full-potential linearized augmented plane wave (FP-LAPW) method within the framework of the spin-polarized density functional theory (DFT) was used to study the structural, electronic, and thermodynamic properties of Ca2CoNbO6 double perovskite compound. The generalized gradient approximation (GGA) described by Perdew-Burke-Ernzerhof (PBE) and GGA + U were used. The results obtained for the electronic properties show a ferrimagnetic and half-metallic behavior of the compound. The novelty of our work is the study of the thermodynamic properties of Ca2CoNbO6 double perovskite such as heat capacity and Debye temperature which showed an important effect of pressure compared to the temperature. [ABSTRACT FROM AUTHOR]

In the present work, a self-consistent ab initio calculation using the full-potential linearized augmented plane wave (FP-LAPW) method within the framework of the spin-polarized density functional theory (DFT) was used to study the structural, electronic, and thermodynamic properties of Ca2CoNbO6 double perovskite compound. The generalized gradient approximation (GGA) described by Perdew-Burke-Ernzerhof (PBE) and GGA + U were used. The results obtained for the electronic properties show a ferrimagnetic and half-metallic behavior of the compound. The novelty of our work is the study of the thermodynamic properties of Ca2CoNbO6 double perovskite such as heat capacity and Debye temperature which showed an important effect of pressure compared to the temperature. [ABSTRACT FROM AUTHOR]

We present first-principles calculations based on the full-potential linearized augmented plane wave (FP-LAPW) method to investigate the structural, elastic, electronic, and magnetic properties of the Heusler compounds V2CoAl and V2CoGa. We explore different magnetic configurations in both regular and inverse Heusler structures: the Cu2MnAl-type and Hg2CuTi-type structures respectively. Our compounds are found to be ferrimagnets in the inverse Heusler structure. To take into account the effects of the strong correlation among the localized d-states, we perform a calculation using the GGA+U method (the general gradient approximation with the Hubbard on-site Coulomb correction U). Then we show that both compounds exhibit a half-metallic character and have a magnetic moment of 2.00 μB per formula unit. This latter statement is coherent with the generalized Slater-Pauling rule (SP). In terms of the band structure calculations, we explain the formation of the indirect energy band gaps in the spin-majority channels. We also use the mean-field approximation (MFA) to discuss the magnetic exchange couplings and predict the Curie temperature for both compounds. [ABSTRACT FROM AUTHOR]

The full-Heusler alloys CoYZ (Z = P, As, Sb, and Bi) were investigated by using the state-of-the-art full-potential linearized augmented plane wave plus local orbital (FP-LAPW + lo) method within the framework of density functional theory (DFT), to understand the structural, electronic, and magnetic properties of these new Heusler alloys. The generalized gradient approximation (GGA) was chosen to define the exchange-correlation potential for studying the structural properties, whereas electronic and magnetic properties were developed by using the GGA + U scheme, where U is the Hubbard term, which explains the Coulomb repulsion and was applied to describe the ' d' electrons. The structural properties indicated that the ferromagnetic states of these compounds are energetically more favorable than the paramagnetic states. Through results on the electronic structures (band structures and densities of states), it is found that all these alloys exhibit a complete half-metallic nature, with half-metallic gaps (E) of 0.632, 0.605, 1.223, and 0.922 eV for CoYP, CoYAs, CoYSb, and CoYBi alloys, respectively. The magnetic properties indicated that the total spin magnetic moments of these Heusler alloys obey the Slater-Pauling rule around value 2 µ approximately. The local magnetic moments of Co and Y transition elements have opposite signs with different intensities, thus revealing the ferromagnetic character. Our study of both electronic and magnetic properties demonstrates in detail that CoYZ (Z = P, As, Sb, and Bi) full-Heusler alloys are complete half-metallic ferrimagnetic materials. [ABSTRACT FROM AUTHOR]

The magnetic properties of mixed-spin S = 3/2 and S = 1/2 ferrimagnetic system have been studied by Monte Carlo simulations. The ground-state phase diagrams of mixed spin-3/2 and spin-1/2 Ising system are given. The critical and compensation temperatures have been found with different values of reduced exchange interactions. The variation of total magnetization with reduced exchange interactions of mixed spins is given with different temperatures and crystal fields. We have also given the variation of total magnetization with crystal field for different reduced exchange interactions and different temperatures. The magnetic hysteresis cycle is found to have different values of reduced exchange interactions, temperatures, and crystal fields. The multiple hysteresis and the superparamagnetic phase are established. [ABSTRACT FROM AUTHOR]

The structural, elastic, electronic and magnetic properties of the MnRhSi Mn-based Heusler alloy were investigated by using first-principles calculations of the full-potential linearized augmented plane wave (FP-LAPW) method. The results of electronic structures show that the MnRhSi exhibits a half-metallic character for a wide range 5.65 to 5.91 Å of lattice constant. The half-metallic behavior is confirmed by the integral value of 3 μ of the total magnetic moment for MnRhSi, which follow the Slater-Pauling rule. [ABSTRACT FROM AUTHOR]

The hexaferrite BaFe O phase was synthesized through the mechanical alloying process followed by subsequent annealing. Rietveld refinements of as-milled powder annealed at 700 C confirm the formation of the BaFe O phase with the presence of an important amount of the α-Fe O phase. Thus, prior mechanical milling shows much lower reaction temperature and less reaction time compared to conventional methods. Further annealing up to 900 and 1100 C could not enable the formation of a single BaFe O phase, reaching an optimum phase composition ratio close to BaFe O / α-Fe O 70/30. The crystallite size was found to be in the nanoscale level but increases with increasing temperature (BaFe O = 20-62 nm; α-Fe O = 31-74 nm). SEM micrographs show that as the annealing temperature rises, the particles become more regular with sharp edges and hexagonal-like shapes. Magnetic measurements reveal that both M and M increase with annealing temperature to reach maximum values at 900 C then remain unchanged, associated with phase composition. The coercivity H increases upon annealing up to 700 C to a much higher value, from 1.7 kOe for as-milled powder to 4.8 kOe. Its value then decreases, attributed to grain (particle) growth (formation of larger particles) due to high annealing temperatures: 900-1100 C. The obtained composites show very interesting magnetic properties and can be considered for potential applications, such as hyperthermia, heavy metal and dye removal, and hard/soft magnetic composites. [ABSTRACT FROM AUTHOR]

La-Na-substituted Co-Zr barium hexaferrites were fabricated using the conventional ceramic sintering method. Characterization techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), vibration sample magnetometry (VSM) and vector network analysis (VNA) were used to analyze structural, magnetic and microwave absorption properties of prepared ferrites. The results show that the magnetoplumbite structures for all the samples have been formed. The magnetic properties such as saturation magnetization ( M ), remanence ( M ) and coercivity ( H ) were calculated from hysteresis loops obtained using a vibrating sample magnetometer (VSM). Also the present investigation demonstrates that microwave absorber using BaLaNaFeCoZrO ferrite can be fabricated for the applications in frequency band from 8.2 to 12.4 GHz, with a reflection loss less than −10 dB for specific frequencies, by controlling the molar ratio of the substituted ions. [ABSTRACT FROM AUTHOR]

The magnetic properties of Ising nanoisland with a ferrimagnetic spin-1 and 3/2 configuration are studied by Monte Carlo simulation. The ground state phase diagrams of mixed spins are obtained. The critical temperature is obtained for different values of exchange interactions and for different crystal fields. The magnetic hysteresis cycle is obtained with different values of temperature, exchange interactions, and crystal field values. The applications of the Monte Carlo to the magnetic properties are extremely restricted for nanoislands, when the value of an interlayer coupling takes a large value, in contrast to a number of bulk studies. [ABSTRACT FROM AUTHOR]

Hard magnetic SrFeAlO hexaferrite and soft magnetic FeO ferrite with cubic spinel structure were synthesized by Pechini method and subsequently mixed and sinterized to obtain an isotropic, polycrystalline SrFeAlO/FeO nanocomposite. A noticeable coercivity of 648 kA/m was observed, together with a saturation magnetization of 0.2 T. The magnetization reversal process for the nanocomposite was described in terms of recoil area and Henkel plots. Field intensity range between 0 and 600 kA/m was identified as a favoring magnetizing interaction, whereas at higher fields, dipolar interactions destabilize magnetized states favoring magnetization reversal. The field interval for which the intergranular exchange interaction facilitates reversible coherent rotation between constituent grains was determined within 0-220 kA/m. Above 220 kA/m, a progressive deterioration of the exchange coupling gives way to the demagnetizing process towards full magnetization reversal. [ABSTRACT FROM AUTHOR]

This work investigates the effect of non-magnetic aluminum (Al) substitution in structural, morphological, magnetic, and dielectric properties of nanosized NiZnAlFeO (0.0 ≤ x ≤ 0.25) synthesized through citrate-gel autocombustion route (CGAC). Structural characterizations were performed by using X-ray powder diffraction (XRD), FT-IR, and scanning electron microscope (SEM). XRD reveals the formation of single-phase cubic spinel with crystallite sizes around 62-57 nm for all Al substituted samples estimated from Williamson-Hall method. Two significant absorption bands around 600 cm and 400 cm are observed from FT-IR spectra of samples under investigation, which confirms the formation of a single-phase cubic spinel. Interionic bond lengths and bond angles confirm the solubility of Al in the spinel lattice and support the observed variation in magnetic properties. Using vibrating sample magnetometer (VSM) saturation magnetization, coercivity has been measured. A decrease in lattice parameter, saturation magnetization with increasing Al concentration was attributed to the difference in the ionic radii and weakening of exchange interactions. The decrease in initial permeability explained on the basis of variation in grain size and porosity. Dielectric constant and dielectric loss decreases with increasing Al concentration and with frequency. [ABSTRACT FROM AUTHOR]

A Monte Carlo simulation based on Metropolis algorithm has been used to investigate the magnetic properties of an Ising ferrimagnetic nanowire on a hexagonal structure, which is made up with L alternate layers of spins σ = ±3/2, ±1/2 and S = ±1, 0. The critical behaviors are studied, in the absence as well as in the presence of crystal field interactions. The obtained results show the existence of some interesting phenomena, such as the appearance of different types of phase diagrams. Furthermore, tricritical point, isolated critical point, critical end point, and compensation behavior are found for appropriate values of the system parameters. [ABSTRACT FROM AUTHOR]

SrLaFeO ( x = 0, 0.15, 0.25, 0.5) hexaferrites were prepared by microwave-assisted sol-gel method. The thermal decomposition process, structural, and magnetic properties of the products were studied by thermal differential scanning calorimeter (DSC), thermogravimetry (TG), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The phase of α-FeO appeared at x = 0.25 and x = 0.5. The coercivity of La-substituted strontium hexaferrites is improved to 5960.2 Oe at x = 0.25. [ABSTRACT FROM AUTHOR]

The Co substitution in Ni-Zn ferrites with respect to their structural and magnetic properties has been investigated in favor to select a material for future electromagnetic interference (EMI) shielding application purpose. NiZnCoFeO ( x = 0, 0.03, 0.09, 0.27) nanoparticles were synthesized using a sol-gel method and annealed at 700C. The prepared NiZnCoFeO samples were characterized for their structural, stoichiometric, and magnetic properties. X-ray diffraction patterns reveal the formation of single-phase spinel cubic structure formed at x = 0.27. The influence of Co doping on structural properties of Ni-Zn ferrite was examined with X-ray diffraction and field emission scanning electron microscopy. The stoichiometry of prepared samples has also been examined by energy-dispersive X-ray spectroscopy. The magnetic behavior was studied using a vibrating sample magnetometer at room temperature. The variations in values of saturation magnetization were explained on the basis of spin canting effect imparted by hematite ( α-FeO) phase with spinel phase. NiZnCoFeO with x = 0.27 possesses best saturation magnetization and can be useful in EMI shielding material. [ABSTRACT FROM AUTHOR]