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To realize room temperature ferromagnetic (FM) semiconductors is still a challenge in spintronics. Many antiferromagnetic (AFM) insulators and semiconductors with high Neel temperature TN are obtained in experiments, such as LaFeO3, BiFeO3, etc. High concentrations of magnetic impurities can be doped into these AFM materials, but AFM state with very tiny net magnetic moments was obtained in experiments because the magnetic impurities were equally doped into the spin up and down sublattices of the AFM materials. Here, we propose that the effective magnetic field provided by a FM substrate could guarantee the spin-dependent doping in AFM materials, where the doped magnetic impurities prefer one sublattice of spins, and the ferrimagnetic (FIM) materials are obtained. To demonstrate this proposal, we study the Mn-doped AFM insulator LaFeO3 with FM substrate of Fe metal by the density functional theory (DFT) calculations. It is shown that the doped magnetic Mn impurities prefer to occupy one sublattice of the AFM insulator and introduce large magnetic moments in La(Fe, Mn)O3. For the AFM insulator LaFeO3 with high TN = 740 K, several FIM semiconductors with high Curie temperature TC > 300 K and the band gap less than 2 eV are obtained by DFT calculations when 1/8 or 1/4 Fe atoms in LaFeO3 are replaced by the other 3d, 4d transition metal elements. The large magneto-optical Kerr effect (MOKE) is obtained in these LaFeO3-based FIM semiconductors. In addition, the FIM semiconductors with high TC are also obtained by spin-dependent doping in some other AFM materials with high TN, including BiFeO3, SrTcO3, CaTcO3, etc. Our theoretical results propose a way to obtain high TC FIM semiconductors by spin-dependent doping in high TN AFM insulators and semiconductors. [ABSTRACT FROM AUTHOR]

A Heat Flux Sensor (HFS) facilitates the visualization of heat flow, unlike a temperature sensor, and is anticipated to be a key technology in managing waste heat. Recently, an HFS utilizing the Anomalous Nernst Effect (ANE) has been proposed garnering significant interest in enhancing the transverse thermopower. However, ideal materials for HFS not only require a large transverse thermopower but also meet several criteria including low thermal conductivity and a bipolar nature of the transverse thermopower, especially a negative transverse thermopower. In this study, we have investigated ANE in amorphous ferrimagnetic GdCo alloys, revealing their numerous advantages as HFS materials. These include a large bipolar transverse thermopower, extremely low thermal conductivity, large negative sensitivity, versatility for deposition on various substrates, and a small longitudinal thermopower. These qualities position GdCo films as promising candidates for the advancement of HFS technology. [ABSTRACT FROM AUTHOR]

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]

The magnetic behavior of two high-entropy alloys, CrMnFeCoNi and CrMnFeCoNi-CN, was investigated under varying degrees of deformation through uniaxial tensile tests. Microstructural, morphological, and crystalline structural analyses using XRD and SEM revealed a uniform and stable austenitic structure in all samples, with no presence of α'-martensite or ε-martensite phases. The main deformation mechanisms identified were twinning and slip dislocation for the CrMnFeCoNi-CN alloy, and slip dislocation for the CrMnFeCoNi alloy at room temperature. The alloys exhibited low magnetic moments attributed to magnetically frustrated configurations. At temperatures below 70 K, distinct magnetic states were observed ranging from paramagnetic to ferrimagnetic and spin-glass-like behavior. Antiferromagnetic interactions were confirmed by a negative paramagnetic Curie temperature for both alloys. The magnetization of the CrMnFeCoNi alloy increased with deformation, reflected in effective magnetic moments varying from 1.81 (0 pct) to 2.60 (20 pct) μB, while for the CrMnFeCoNi-CN alloy remained stable around 2.39 to 2.48 μB. The magnetization of the CrMnFeCoNi-CN alloy was found to be higher than that of the CrMnFeCoNi alloy, suggesting that the presence of C and N as alloying elements can enhance magnetization to some extent. [ABSTRACT FROM AUTHOR]

Symmetry-protected band degeneracy, coupled with a magnetic order, is the key to realizing novel magnetoelectric phenomena in topological magnets. While the spin-polarized nodal states have been identified to introduce extremely-sensitive electronic responses to the magnetic states, their possible role in determining magnetic ground states has remained elusive. Here, taking external pressure as a control knob, we show that a metal-insulator transition, a spin-reorientation transition, and a structural modification occur concomitantly when the nodal-line state crosses the Fermi level in a ferrimagnetic semiconductor Mn3Si2Te6. These unique pressure-driven magnetic and electronic transitions, associated with the dome-shaped Tc variation up to nearly room temperature, originate from the interplay between the spin-orbit coupling of the nodal-line state and magnetic frustration of localized spins. Our findings highlight that the nodal-line states, isolated from other trivial states, can facilitate strongly tunable magnetic properties in topological magnets. The coupling between topological electronic properties and magnetic order offers a promising route for magnetoelectric control with great potential for both applications and fundamental physics. Here, Susilo et al demonstrate the rich tunability of magnetic properties in nodal-line magnetic semiconductor Mn3Si2Te6 using pressure as control knob. [ABSTRACT FROM AUTHOR]

Symmetry-protected band degeneracy, coupled with a magnetic order, is the key to realizing novel magnetoelectric phenomena in topological magnets. While the spin-polarized nodal states have been identified to introduce extremely-sensitive electronic responses to the magnetic states, their possible role in determining magnetic ground states has remained elusive. Here, taking external pressure as a control knob, we show that a metal-insulator transition, a spin-reorientation transition, and a structural modification occur concomitantly when the nodal-line state crosses the Fermi level in a ferrimagnetic semiconductor Mn3Si2Te6. These unique pressure-driven magnetic and electronic transitions, associated with the dome-shaped Tc variation up to nearly room temperature, originate from the interplay between the spin-orbit coupling of the nodal-line state and magnetic frustration of localized spins. Our findings highlight that the nodal-line states, isolated from other trivial states, can facilitate strongly tunable magnetic properties in topological magnets. The coupling between topological electronic properties and magnetic order offers a promising route for magnetoelectric control with great potential for both applications and fundamental physics. Here, Susilo et al demonstrate the rich tunability of magnetic properties in nodal-line magnetic semiconductor Mn3Si2Te6 using pressure as control knob. [ABSTRACT FROM AUTHOR]

The dynamic magnetic and thermodynamic behaviors of the mixed-spin (1/2, 1, 3/2) Ising edge-modified graphene-like nanoparticles in a time-dependent magnetic field are studied by Monte Carlo simulation. The influence of temperature, exchange coupling, crystal field, and time-dependent magnetic field on the dynamic order parameter, magnetic susceptibility, and internal energy are investigated. The simulations reveal that the compensation behavior of the system occurs in a certain parameter range. Strong crystal field and weak exchange coupling promote the compensation behavior in the system, while increasing the amplitude of the oscillating magnetic field reduces the compensation temperature. Furthermore, the system shows the interesting multiple dynamic hysteresis behaviors under the influence of different parameters. [ABSTRACT FROM AUTHOR]

In this paper, the compensation characteristics and hysteresis loops of a ferrimagnetic mixed-spin diluted fullerene-like (XY)540 are studied based on Monte Carlo method. We show the ground-state phase diagrams in order to explore the stable configuration states. The temperature dependence of magnetization, magnetic susceptibility, internal energy, specific heat, and entropy are presented. The phase diagram including compensation temperature Tcomp and phase change temperature Tc is obtained. The multi-loop hysteresis phenomena under the influence of diverse physical parameters are observed. Finally, the critical exponents of the fullerene-like (XY)540 are obtained. [ABSTRACT FROM AUTHOR]

Symmetry-protected band degeneracy, coupled with a magnetic order, is the key to realizing novel magnetoelectric phenomena in topological magnets. While the spin-polarized nodal states have been identified to introduce extremely-sensitive electronic responses to the magnetic states, their possible role in determining magnetic ground states has remained elusive. Here, taking external pressure as a control knob, we show that a metal-insulator transition, a spin-reorientation transition, and a structural modification occur concomitantly when the nodal-line state crosses the Fermi level in a ferrimagnetic semiconductor Mn3Si2Te6. These unique pressure-driven magnetic and electronic transitions, associated with the dome-shaped Tc variation up to nearly room temperature, originate from the interplay between the spin-orbit coupling of the nodal-line state and magnetic frustration of localized spins. Our findings highlight that the nodal-line states, isolated from other trivial states, can facilitate strongly tunable magnetic properties in topological magnets. The coupling between topological electronic properties and magnetic order offers a promising route for magnetoelectric control with great potential for both applications and fundamental physics. Here, Susilo et al demonstrate the rich tunability of magnetic properties in nodal-line magnetic semiconductor Mn3Si2Te6 using pressure as control knob. [ABSTRACT FROM AUTHOR]

This research focuses on the formation and assessment of sol–gel auto-combustion-produced nanocrystalline Co0.40Ni0.6AlxFe2−xO4 (x = 0.00, 0.05, 0.1, 0.2) ferrites. The investigation explores the structural, morphological, electrical, dielectric, and magnetic characteristics of the spinel ferrites sintered at different temperatures (850 °C and 950 °C), with a specific emphasis on the impact of Al3+ substitution. A cubic single-phase spinel structure exhibiting excellent crystallinity and homogeneity is found across all samples, based on XRD evaluation. The nanoparticles had typical crystallite sizes between 40 and 48 nm and average particle sizes between 122 and 186 nm. Increasing Al3+ content resulted in increased nanoparticle porosity. According to infrared spectroscopy, the adsorption band v1 rose from 538 to 554 cm−1 whereas the v2 band dropped from 374 to 366 cm−1. With an increase in Al3+ content, the experimental magnetic moment (ηexp) and saturation magnetization (Ms) of the nanoparticles showed a notable upward trend. Furthermore, the samples sintered at 950 °C displayed higher AC resistivity, attributed to a reduction of the hopping electron within the grains. All of the ferrite nanoparticles under investigation also showed high coercivity values (1028.32–1222.76 Oe), designating them as ferrimagnetic materials and emphasizing the possibility for use in spintronics, high-frequency and microwave equipment like radar, antenna, and so on. [ABSTRACT FROM AUTHOR]

The atomic structures, growth patterns, new spintronic, magneto-optic, and electrical properties of 2D armchair nanoribbons of group-IV transition metal nitrides (TiN, ZrN, and HfN) have been investigated. The atomic unit cells of TiN, ZrN, HfN, TiZrN, TiHfN, and ZrHfN have been transformed into the matching armchair nanoribbons. By comparing the proposed nanoribbon to the bulk and monolayer structures of these metal nitrides, the structural stability, density, and projected density of states, band structure, magnetic behavior, and polarization were evaluated. The outcomes demonstrate that, in comparison to the crystalline structure, the suggested systems exhibit ferrimagnetic behavior and a remarkable magnetic moment. Also, a higher magnetic moment of about 24 μB in the supercells of the suggested nanoribbons was discovered due to the increased atom count. The proposed structures demonstrated indirect band gap semiconductor capabilities in the range between 1.66 eV and 2.16 eV which is again an unknown phenomenon in the bulk structure of transition metal nitrides. Owing to these characteristics, the proposed structures can be employed in many optoelectronic applications, such as solar cell devices, LEDs, laser diodes, and optical fibers where the band gap is the key requirement. Apart from this, they can also be useful in coating biomedical implanted chips, transformers, switches, and batteries. Memory storage devices will also benefit from the unique characteristics of the proposed nanoribbon structures. [ABSTRACT FROM AUTHOR]

Ferrimagnetic Mn0.25Co0.75Fe2O4 (MCF) nanoparticles were synthesized via sol–gel autocombustion method. Polyaniline (PANI) and PANI nanocomposites with MCF as filler (PANI/MCF) were synthesized through chemical oxidative in-situ polymerization of aniline under the presence of varying weight percentage of the MCF (10%, 20% and 50%). The MCF, PANI and PANI/MCF nanocomposites were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analyzer (TGA), field emission scanning electron microscopy equipped with elemental detection (FESEM-EDAX) and vibrating sample magnetometer. The XRD and FTIR spectra confirmed the formation of pure phase with high crystallinity for all the samples. TGA study showed the increased thermal stability of PANI with addition of MCF. MCF and PANI/MCF nanocomposites showed ferrimagnetic hysteresis loop under external magnetic field at room temperature. Additionally, the ac conductivity, dielectric and electrical properties as a function of frequency ranging from 100 Hz to 120 MHz, were investigated for all the samples using impedance analyzer at room temperature. Dielectric, TGA and magnetic studies showed that PANI/MCF with 50 weight percentage of MCF has maximum ac conductivity, thermal stability and moderate magnetic properties. Hence, it could be a potential candidate to be used as dielectric material in high frequency capacitors and for electromagnetic interference shielding material at high frequency. [ABSTRACT FROM AUTHOR]

Magnetic fibers were synthesized by the lumen loading method using bamboo fibers as a cellulose source and cobalt ferrite nanoparticles with polyethylenimine (PEI) as a retention aid. Bamboo fiber is a significant fibrous raw material, and cobalt ferrite particles are suitable for magnetic modification. The resulting composite retained the intrinsic features of cellulose fiber while gaining the magnetic properties of nanoparticles. Cobalt ferrite nanoparticles were synthesized using a sol–gel technique and coated with tetraethyl orthosilicate (TEOS) molecules before being functionalized with PEI. Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and vibrating-sample magnetometry (VSM) were used to characterize the samples. The nanoparticles produced had an inverse cubic spinel crystalline structure and exhibited ferrimagnetic activity. The coercivity value for modified fiber produced was greater than 200 Oe, indicating that it may be utilized for magnetic recording. Lumen-Loading procedure of CoFe2O4-SiO2-PEI on the disintegrated bamboo fibers [ABSTRACT FROM AUTHOR]

Magnetic skyrmions with nontrivial topologies have great potential to serve as memory cells in novel spintronic devices. Small skyrmions were theoretically and experimentally confirmed to be generated under the influence of external fields in ferrimagnetic films via Dzyaloshinskii–Moriya interactions (DMIs). However, this topological state has yet to be verified in ferrimagnetic crystals, especially in the absence of external fields and DMIs. Here, spontaneous biskyrmions were directly observed in the Tb0.2Gd0.8Co2 ferrimagnetic crystal with a Kagome lattice using Lorentz transmission electron microscopy. The high-density biskyrmions exhibited a small size (approximately 50 nm) over a wide temperature range, were closely related to subtle magnetic interaction competition, and coexisted with some broken stripes that could be easily converted into zero-field biskyrmions by utilizing proper field-cooling manipulation. These results can be used to establish a platform for investigating functional sub-50-nm skyrmions in ferrimagnetic crystals and to facilitate advanced applications in magnetic devices. Revolutionising Spintronics: Zero-Field Biskyrmions in Ferrimagnetic Kagome Lattice Scientists have found a new method to control small skyrmions, which are tiny magnetic patterns, in ferrimagnetic materials (materials that have a net magnetic moment even without an external magnetic field arising from the two opposite magnetic sublattices). The research, led by S.L. Zuo and K.M. Qiao, revealed that these skyrmions can be maintained in ferrimagnetic materials without requiring an external magnetic field. The researchers used a technique called Lorentz transmission electron microscopy to observe the skyrmions in a specific ferrimagnetic crystal, Tb0.2Gd0.8Co2. They discovered that the skyrmions remained stable across a broad temperature range and could be easily controlled by altering the temperature or applying a minor magnetic field. This finding could be crucial for the creation of future spintronic devices, devices that use the rotation of electrons to store and process data. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author. [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]

Temperature-dependent magnetization of core-shell and alloy nanoparticles of cobalt (Co)/nickel (Ni) is investigated within the context of the classical spin Hamiltonian and Monte Carlo simulations. The results of our study indicate that the average temperature-dependent magnetization and magnetic-ordering temperature have a significant influence from variations in the core-shell ratio and chemical order in core-shell nanoparticles. Also, the alloy fraction of Co(Ni) strongly influences the magnetic ordering temperature of the nanoparticles. It is noticed that in alloy nanoparticles, the rise of the magnetic ordering temperature with the increase in Co proportion is linear. However, the same is not true for core-shell nanoparticles where the magnetic-ordering temperature deviates from the straight line fit of alloy T c . It is ascertained that core-shell Co@Ni and Ni@Co nanoparticles sustain higher temperatures in their ferromagnetic state. In the ferrimagnetic nanoparticles, there is a reduction in the saturation magnetization and a display of compensation behavior. [ABSTRACT FROM AUTHOR]

The effect of temperature on electrochemical properties of Ni82.3Cr7Fe3Si4.5B3.2 glassy alloy in different acid proticity has been investigated utilizing AC and DC methods. Firstly, the handling of experimental data on the temperature dependence of charge transfer resistance, as well as corrosion current density permits us to determine the values of classical Arrhenius parameters as well as the thermodynamic ones considered approximately independent of temperature. This leads us to deduce a global interpretation on the phenomenon of corrosion and polarization. Secondly, the deviation to the linearity of the Arrhenius behavior and the real dependence on temperature of the thermodynamic parameters, permit us to clearly quantify the effect of the acid proticity and define, for the first time, the concept of current Arrhenius parameters and the current thermodynamic ones, as well as the modeling of the enthalpy–enthalpy compensation. Moreover, the effect of temperature can be investigated using the Vogel–Fulcher–Tammann model to reveal that the corresponding Vogel temperature has an interesting physical meaning. [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]

In this paper, we study the structural, magnetic, electronic, optical, thermoelectric, and thermodynamic properties of the perovskite ErMn0.5Fe0.5O3. The Wien2K code's implementation of density functional theory (DFT) was used to perform the first principle calculations for this compound utilizing the full potential linearized augmented plane wave form with Total Potential (FP-LAPW) approach. The GGA-PBE and the exchange–correlation potential with Hubbard correction (GGA+U) were used to calculte the bulk modulus, its first derivative, and the optimal lattice parameters. The compounds display metallic nature in the NM and FM states. While in the AFM state, the compound behaves as a half-metal. The electronic transport coefficients have been calculated. The entropy, thermal expansion coefficient, Debye temperature, and heat capacity Cv are calculated. The Monte-Carlo calculation method shows that the magnetization of this material undergoes a second-order transition at a temperature of Néel, TN = 248 K. [ABSTRACT FROM AUTHOR]

The magnetic susceptibility of Fe1 –xCoxCr2S4 solid solutions in the FeCr2S4-rich part of the FeCr2S4–CoCr2S4 system has been studied by static and dynamic methods. The magnetic measurements were performed at temperatures from 5 to 300 K in static (50 Oe and 45 kOe) and ac magnetic fields (field amplitude Hac = 1 Oe; ac field frequencies ν = 100, 1000, and 10 000 Hz). We have determined the temperatures of the magnetic transformations in the system and identified their nature. The results demonstrate that the temperature of the ferrimagnetic phase transition (TC) in Fe1 –xCoxCr2S4 increases with increasing cobalt content. The materials with x = 0–0.5 have been shown to undergo a transition to a spin glass state, evidenced by a shift of maxima in temperature dependences of the imaginary part of their dynamic susceptibility. [ABSTRACT FROM AUTHOR]

The interplay between spin-orbit interaction and magnetic order is one of the most active research fields in condensed matter physics and drives the search for materials with novel, and tunable, magnetic and spin properties. Here we report on a variety of unique and unexpected observations in thin multiferroic Ge1−xMnxTe films. The ferrimagnetic order parameter in this ferroelectric semiconductor is found to switch direction under magnetostochastic resonance with current pulses many orders of magnitude lower as for typical spin-orbit torque systems. Upon a switching event, the magnetic order spreads coherently and collectively over macroscopic distances through a correlated spin-glass state. Utilizing these observations, we apply a novel methodology to controllably harness this stochastic magnetization dynamics. GeTe is a ferroelectric semiconductor with broken inversion symmetry, which leads to a large spin-orbit interaction. When doped with small amounts of manganese, it becomes magnetoelectric. Here, Krempasky et al show that the ferrimagnetic ordering of Mn-doped GeTe can be switched with unusually small currents under specific resonant conditions, orders of magnitude smaller than typical for spin-orbit torque based switching. [ABSTRACT FROM AUTHOR]

Isolated magnetic skyrmions are stable, topologically protected spin textures that are at the forefront of research interests today due to their potential applications in information technology. A distinct class of skyrmion hosts are rare earth - transition metal (RE-TM) ferrimagnetic materials. To date, the nature and the control of basic traits of skyrmions in these materials are not fully understood. We show that for an archetypal ferrimagnetic material DyCo3 that exhibits a strong perpendicular anisotropy, the ferrimagnetic skyrmion size can be tuned by an external magnetic field. Moreover, by taking advantage of the high spatial resolution of scanning transmission X-ray microscopy (STXM) and utilizing a large x-ray magnetic linear dichroism (XMLD) contrast that occurs naturally at the RE resonant edges, we resolve the nature of the magnetic domain walls of ferrimagnetic skyrmions. We demonstrate that through this method one can easily discriminate between Bloch and Néel type domain walls for each individual skyrmion. For all isolated ferrimagnetic skyrmions, we observe that the domain walls are of Néel-type. This key information is corroborated with results of micromagnetic simulations and allows us to conclude on the nature of the Dzyaloshinskii-Moriya interaction (DMI) which concurs to the stabilisation of skyrmions in this ferrimagnetic system. Establishing that an intrinsic DMI occurs in RE-TM materials will also be beneficial towards a deeper understanding of chiral spin texture control in ferrimagnetic materials. Magnetic skyrmions are topological spin textures that have potential implications for spintronic devices but greater control over their stability and physical characteristics are first required. Here, the authors study the formation of skyrmions in ferrimagnetic thin films of DyCo3 and using a combination of X-ray measurements determine them to be of the Néel type. [ABSTRACT FROM AUTHOR]

Magnetization dependences of CoxZn1 –xFe2O4 nanoparticles ( , 0.1, 0.2, 0.3, 0.4, 0.5) synthesized with the citrate precursor technique on an external magnetic field and temperature are presented. Ferrimagnetic order in nanoparticles with appeared at temperatures, T, exceeding room temperature, and in nanoparticles with and 0.1 at T near 100 K. The saturation magnetization, , remnant magnetization, , and the coercive force, , increase with x increase and the temperature decrease. reached very high value: of NPs with equals to 106.6 emu/g at 100 K while, according to the literature data, of stoichiometric bulk Co ferrite equals to 90 emu/g at 4.2 K. Correlations between concentration dependences of magnetic and electric properties has been revealed and explained qualitatively. [ABSTRACT FROM AUTHOR]

By employing Monte Carlo simulation with the metropolis algorithm, the magnetic properties of hexagonal decorated nanoparticle with a mixed-spin (3/2, 1) configuration under an applied magnetic field were analyzed. The influence of exchange couplings and anisotropies on the magnetic and thermodynamic properties of the system were studied. We obtained the various characteristic curves of the magnetization, susceptibility, internal energy, specific heat, and hysteresis loops. The multiple-loop hysteresis behaviors were discovered under certain conditions. Furthermore, we also plotted the variation curve of magnetization with the external magnetic field under the effect of different parameters and found that the magnetization plateaus are based on the exchange couplings, anisotropies, and spin state. [ABSTRACT FROM AUTHOR]

The magnetic properties of a ferrimagnetic-type bathroom-tile (4–8) core–shell nanostructure with the mixed spins (3/2, 7/2) are studied using Monte Carlo simulations. The aim of this paper is to study the impact of the core size on the magnetic properties of a core–shell nanosystem. We start by illustrating and discussing the ground-state phase diagrams in different physical parameter planes. Then, we study the thermal behavior of magnetizations and susceptibilities. Furthermore, we examine the core size effect on the compensation temperature. Finally, we discuss the variation of the total magnetization as a function of the crystal and external magnetic fields. [ABSTRACT FROM AUTHOR]

In some materials exhibiting field-induced first-order transitions (FOTs), the equilibrium phase-transition line is hidden by the hysteresis region associated with the FOT. In general, phase diagrams form the basis for the study of material science, and the profiles of phase-transition lines separating different thermodynamic phases include comprehensive information about thermodynamic quantities, such as latent heat. However, in a field-induced FOT, the equilibrium phase-transition line cannot be precisely determined from measurements of resistivity, magnetization, etc, especially when the transition is accompanied by large hysteresis. Here, we demonstrate a thermodynamics-based method for determining the hidden equilibrium FOT line in a material exhibiting a field-induced FOT. This method is verified for the field-induced FOT between antiferromagnetic and ferrimagnetic states in magneto-electric compounds ( Fe 0.95 Zn 0.05 ) 2 Mo 3 O 8 . The equilibrium FOT line determined based on the Clausius–Clapeyron equation exhibits a reasonable profile in terms of the third law of thermodynamics, and it shows marked differences from the midpoints of the hysteresis region. Our findings highlight that for a field-induced FOT exhibiting large hysteresis, care should be taken for referring to the hysteresis midpoint line when discussing field-induced latent heat or magnetocaloric effects. [ABSTRACT FROM AUTHOR]

α-Fe2O3/Fe3O4/g-C3N4 nanocomposites were prepared in-situ by solution combustion as magnetically separable photocatalysts using ferric nitrate as oxidant, glycine as organic fuel, and g-C3N4. The effects of various amounts of iron oxides, on the magnetic, optical, and photocatalytic properties were explored by different characterization methods. The magnetite (Fe3O4) phase as ferrimagnetic material disappeared with the increase in ferric nitrate contents, leading to the decrease of magnetic properties. The bandgap energy decreased from 2.8 to 1.6 eV with the increase of the hematite (α-Fe2O3) phase.The photocatalytic results showed that the type and amount of iron oxides had a significant effect on the decolorization of methylene blue, rhodamine B and methyl orange dyes under visible-light irradiation. The activity of the nanocomposite sample containing 37 wt. % iron oxides was more effective than that of the pristine g-C3N4 sample to photodegrade the methylene blue, rhodamine B and methyl orange, respectively. Moreover, the nanocomposites exhibited a higher photocurrent density than that of the pristine g-C3N4, mainly due to their lower charge recombination rate. [ABSTRACT FROM AUTHOR]

α-Fe2O3/Fe3O4/g-C3N4 nanocomposites were prepared in-situ by solution combustion as magnetically separable photocatalysts using ferric nitrate as oxidant, glycine as organic fuel, and g-C3N4. The effects of various amounts of iron oxides, on the magnetic, optical, and photocatalytic properties were explored by different characterization methods. The magnetite (Fe3O4) phase as ferrimagnetic material disappeared with the increase in ferric nitrate contents, leading to the decrease of magnetic properties. The bandgap energy decreased from 2.8 to 1.6 eV with the increase of the hematite (α-Fe2O3) phase.The photocatalytic results showed that the type and amount of iron oxides had a significant effect on the decolorization of methylene blue, rhodamine B and methyl orange dyes under visible-light irradiation. The activity of the nanocomposite sample containing 37 wt. % iron oxides was more effective than that of the pristine g-C3N4 sample to photodegrade the methylene blue, rhodamine B and methyl orange, respectively. Moreover, the nanocomposites exhibited a higher photocurrent density than that of the pristine g-C3N4, mainly due to their lower charge recombination rate. [ABSTRACT FROM AUTHOR]

Reservoir computing is a brain heuristic computing paradigm that can complete training at a high speed. The learning performance of a reservoir computing system relies on its nonlinearity and short-term memory ability. As physical implementation, spintronic reservoir computing has attracted considerable attention because of its low power consumption and small size. However, few studies have focused on developing the short-term memory ability of the material itself in spintronics reservoir computing. Among various magnetic materials, spin glass is known to exhibit slow magnetic relaxation that has the potential to offer the short-term memory capability. In this research, we have quantitatively investigated the short-term memory capability of spin cluster glass based on the prevalent benchmark. The results reveal that the magnetization relaxation of Co, Si-substituted Lu3Fe5O12 with spin glass behavior can provide higher short-term memory capacity than ferrimagnetic material without substitution. Therefore, materials with spin glass behavior can be considered as potential candidates for constructing next-generation spintronic reservoir computing with better performance. [ABSTRACT FROM AUTHOR]

In this work, the magnetothermal characteristics and magnetocaloric effect in YFe3 and HoFe3 compounds are calculated as function of temperature and magnetic field. These properties were investigated using the two-sublattice mean field model and the first-principles DFT calculation using the WIEN2k code. The two-sublattice model of the mean-field theory was used to calculate the temperature and field-dependences of magnetization, magnetic heat capacity, magnetic entropy, and the isothermal change in entropy ∆Sm. We used the WIEN2k code to determine the elastic constants and, subsequently, the bulk and shear moduli, the Debye temperature, and the density-of-states at Ef. According to the Hill prediction, YFe3 has bulk and shear moduli of roughly 99.3 and 101.2 GPa respectively. The Debye temperature is ≈ 500 K, and the average sound speed is ≈ 4167 m/s. In fields up to 60 kOe and at temperatures up to and above the Curie point for both substances, the trapezoidal method was used to determine ∆Sm. For instance, the highest ∆Sm values for YFe3 and HoFe3 in 30 kOe are approximately 0.8 and 0.12 J/mol. K, respectively. For the Y and Ho systems, respectively, the adiabatic temperature change in a 3 T field decreases at a rate of around 1.3 and 0.4 K/T. The ferro (or ferrimagnetic) to paramagnetic phase change in these two compounds, as indicated by the temperature and field dependences of the magnetothermal and magnetocaloric properties, ∆Sm and ∆Tad, is a second-order phase transition. The Arrott plots and the universal curve for YFe3 were also calculated and their features give an additional support to the second order nature of the phase transition. [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]

We studied some magnetic behaviors of the Ising model in a single-wall mixed spin (σ = ½, S = 1) triangular nanotube using the effective field theory with correlations (EFTC), and the differential operator technique (DOT). The effects of exchange interactions as well as the temperature and the applied field on the magnetic properties of the nanotube, such as isotherm and spontaneous magnetizations, were carefully analyzed. We demonstrated that the low-temperature behavior of the magnetization is very sensitive to the exchange interactions involved, especially in the case of competitional couplings. Besides the phase diagram, unusual phenomena have been discovered, especially for opposite exchange interactions where magnetization plateaus and frustration are observed. Several forms of ferrimagnetism have been revealed for judicious choices of exchange and single-ion anisotropy. One of the most notable effects is the occurrence of magnetization jumps and fractional plateaus due to both the geometry and the competition between exchange couplings, on the one hand, and the applied magnetic field, on the other hand. Such plateaus could provide a path toward potential applications of functional ferrimagnets in spintronics and device regulation. [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]

Magnetic skyrmions are meta-stable spin structures that naturally emerge in magnetic materials. While a vast amount of effort has gone into the study of their properties, their counterpart of opposite topological charge, the anti-skyrmion, has not received as much attention. We aim to close this gap by deploying Monte Carlo simulations of spin-lattice systems in order to investigate which interactions support anti-skyrmions, as well as skyrmions of Bloch and Néel type. We find that the combination of ferromagnetic exchange and Dzyaloshinskii–Moriya (DM) interactions is able to stabilize each of the three types, depending on the specific structure of the DM interactions. Considering a three-dimensional spin lattice model, we provide a finite-temperature phase diagram featuring a stable anti-skyrmion lattice phase for a large range of temperatures. In addition, we also shed light on the creation and annihilation processes of these anti-skyrmion tubes and study the effects of the DM interaction strength on their typical size. [ABSTRACT FROM AUTHOR]

The electronic structure, magneto-optic properties of two systems: Sr2FeReO6 and Sr2CrWO6 are investigated using the FPLAPW employing the GGA approximation. Our results show that the two systems have a half metallic character. The obtained magnetic moments indicate that first is ferromagnetic, while the second is ferrimagnetic. The DFT was used to calculate the magnetic moment and the exchange energies. The obtained results are used in Monte Carlo simulations (MCS) to determine some magnetic parameters such as: magnetization, susceptibility, relative cooling power, adiabatic change in temperature and magnetic entropy under temperature effect. [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]

Structural, magnetic, electronic, elastic, thermodynamic, optical, and thermoelectric properties of full-Heusler alloys Co2YSn (Y = Ti; Zr; Hf) were determined using density functional theory-based WIEN2k code within GGA and GGA + U approximations for exchange correlation functions. The calculated formation energies and elastic parameters demonstrate the stability of these alloys. It was also observed that the studied compounds have a ductile structure and exhibit anisotropic behavior. The magnetic moment of these systems is equal to 2 μB, which conforms to the Slater–Pauling rule. In addition, the half-metallic ferrimagnetic behavior and good bandgap in the minority spin are showed for all compounds. The optical properties are systematically studied by computing the optical parameters. The existence of bandgaps with minimal energy loss in IR and visible regions makes these materials suitable candidates for optoelectronic devices. The thermoelectric properties of these systems were also examined in terms of temperature and chemical potential. [ABSTRACT FROM AUTHOR]

In order to investigate the sintering temperature requirements of low-temperature co-fired ceramics (LTCC) technology, the effects of Bi2O3–Nb2O5 addition on microstructures and magnetic performances of low-temperature sintered Li0.42Zn0.27Ti0.11Mn0.1Fe2.1O4 (LiZnTiMn) ferrites were studied. The microstructure, compactness, and ferromagnetism of samples with different Bi2O3–Nb2O5 contents were measured and analyzed in the sintering temperature 880–920 °C. The results demonstrate that adding an appropriate amount of Bi2O3–Nb2O5 significantly enhances the growth of grains and reduces the abnormal grains, leading to uniform and dense LiZnTiMn ferrite ceramics. The X-ray diffraction and scanning electron microscopy results show that pure spinel phase LiZnTiMn ferrite ceramics were obtained, and proper Bi2O3–Nb2O5 addition could achieve higher densification and better grain growth. Specifically, the performance of the samples doped with 0.5 wt% Bi2O3 and 0.1 wt% Nb2O5 additives was more prominent with the following parameters: Bs = 328.34 mT, Br/Bs = 0.875, Hc = 152.26 A/m, and ΔH = 161.2 Oe. The results indicate that LiZnTiMn ferrite doped with appropriate amounts of Bi2O3–Nb2O5 additives has better gyromagnetic properties and can be well combined with LTCC technology and phased array radar system. [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]

Two-dimensional (2D) ferromagnets with high Curie temperature TC are desirable for spintronics applications. However, they are rarely obtained in experiments mainly due to the challenge of synthesizing high-quality 2D crystals, and their TC values are below room temperature. Using first-principles calculations, we design a family of stable 2D FenGeTe2 (4 ≤ n ≤ 7) ultrathin films with coexisting itinerant and localized magnetism. Among them, 2D Fe3GeTe2 and Fe4GeTe2 are ferromagnetic metals with TC = 138 and 68 K; 2D Fe5GeTe2, Fe6GeTe2, and Fe7GeTe2 are Néel's P-, R-, and R-type ferrimagnetic metals with TC = 320, 450, and 570 K. A thickness-induced magnetic phase transition originates from competition between itinerant and localized states, and also correlates with Fe3+ and Fe2+ content. A valence/orbital-dependent magnetic exchange model is proposed for these effects. Our results reveal a universal mechanism for magnetic coupling in complex magnetic systems. 2D magnetism offers the prospect of ordered and controllable magnetic states at reduced dimensions and there is a desire to obtain materials which can realise these properties at room temperature. Here, the authors use first-principles calculations to demonstrate that a family of 2D FenGeTe-based ultrathin films with varying Fe content can exhibit a range of magnetic properties at elevated temperatures. [ABSTRACT FROM AUTHOR]

We investigated the structural, magneto-electronic, and thermoelectric properties of V2CoZ (Z = Ga, and Ge) Heusler alloys using the ab-initio method. The XA-type structure within the ferrimagnetic phase is more energetically stable than other phases through the chemical stability so the negative value of energy formation that both compounds are favorable and synthesizable experimentally. Both compounds' mechanical properties show anisotropic ductile materials. In addition to their half-metallic ferrimagnetic behavior with an integer total magnetic moment, according to magneto-electronic calculations. Boltzmann's transport theory was also used to investigate the thermoelectric response. Our findings show that these Heusler alloys have a lot of potential for thermo-spintronic devices. [ABSTRACT FROM AUTHOR]

Magnetic topological phases of quantum matter are an emerging frontier in physics and materials science, of which kagome magnets appear as a highly promising platform. Here, we explore magnetic correlations in the recently identified topological kagome system TbMn6Sn6 using muon spin rotation, combined with local field analysis and neutron diffraction. Our studies identify an out-of-plane ferrimagnetic structure with slow magnetic fluctuations which exhibit a critical slowing down below T C1 * ≃ 120 K and finally freeze into static patches with ideal out-of-plane order below TC1 ≃ 20 K. We further show that hydrostatic pressure of 2.1 GPa stabilises the static out-of-plane topological ferrimagnetic ground state in the whole volume of the sample. Therefore the exciting perspective arises of a magnetically-induced topological system whose magnetism can be controlled through external parameters. The present results will stimulate theoretical investigations to obtain a microscopic understanding of the relation between the low-temperature volume-wise magnetic evolution of the static c-axis ferrimagnetic patches and the topological electronic properties in TbMn6Sn6. Kagome metals house a range of competing ground states leading to superconducting as well as topological features and so there has been significant recent interest in their underlying physics. Here, the authors use muon-spin rotation to identify slow fluctuations and low-temperature volume-wise magnetic evolution of the static c-axis ferrimagnetic patches in TbMn6Sn6, which seems to be intimately coupled to its topological electronic properties. [ABSTRACT FROM AUTHOR]

Magnetic topological phases of quantum matter are an emerging frontier in physics and materials science, of which kagome magnets appear as a highly promising platform. Here, we explore magnetic correlations in the recently identified topological kagome system TbMn6Sn6 using muon spin rotation, combined with local field analysis and neutron diffraction. Our studies identify an out-of-plane ferrimagnetic structure with slow magnetic fluctuations which exhibit a critical slowing down below T C1 * ≃ 120 K and finally freeze into static patches with ideal out-of-plane order below TC1 ≃ 20 K. We further show that hydrostatic pressure of 2.1 GPa stabilises the static out-of-plane topological ferrimagnetic ground state in the whole volume of the sample. Therefore the exciting perspective arises of a magnetically-induced topological system whose magnetism can be controlled through external parameters. The present results will stimulate theoretical investigations to obtain a microscopic understanding of the relation between the low-temperature volume-wise magnetic evolution of the static c-axis ferrimagnetic patches and the topological electronic properties in TbMn6Sn6. Kagome metals house a range of competing ground states leading to superconducting as well as topological features and so there has been significant recent interest in their underlying physics. Here, the authors use muon-spin rotation to identify slow fluctuations and low-temperature volume-wise magnetic evolution of the static c-axis ferrimagnetic patches in TbMn6Sn6, which seems to be intimately coupled to its topological electronic properties. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis of single-phase nanoparticles of Bi3+-doped cobalt zinc ferrite by employing the sol–gel auto combustion technique where the average crystallite size ranges between 11 and 18 nm. Fourier transform infrared spectra show the presence of two prominent peaks around 400 cm−1 and 593 cm−1. The magnetic studies reveal that all the samples exhibit ferrimagnetic ordering where both the saturation magnetization and magnetocrystalline anisotropy decrease due to the spin canting effect caused by the Bi ions. The dielectric constant decreases, while the permeability increases with Bi3+ ion substitution, followed by a decrease in the magnetic loss. The total shielding effectiveness (SET) value increased with doping and a maximum value of 12.8 dB was reported for the composition x = 0.15. The shielding effectiveness due to the absorption (SEA) decreases with frequency, while the shielding effectiveness due to reflection (SER) increases with frequency and doping, which shows that the sample is a good choice for the electromagnetic interference filter application and multilayer inductor chip fabrication. [ABSTRACT FROM AUTHOR]

The physical properties of La3+-doped Cu–Cd ferrites (CCF ferrites) were investigated with an aim to analyze the effect of large-sized La3+ cations on the structure, morphology, magnetization, permeability, and dielectric parameters. Temperature-dependent permeability and permittivity of CCF ferrites are in good agreement with locomotion of grains and grain boundaries. The CCF ferrites are synthesized by a sol–gel method. The Rietveld refinement promoted for the structural confirmation reveals the cubic spinel structure of CCF ferrites. The morphology of all ferrites investigated by surface scanning analysis images indicates the presence of cubical and triangular crystallites. The analysis of magnetic parameters of CCF ferrites measured through a high-field magnetization evidences magnetic transition from paramagnetic to ferrimagnetic phase. The magnetic permeability increases and magnetic loss decreases on enhancing La3+ content from 0.0 to 0.20. When temperature is stepped up from 25 to 150 °C, the permeability is improved. The increase in permittivity and decrease in ac conductivity is assigned to increase of grain size and reduction of grain boundaries as explained by Maxwell–Wagner model. The magnetic and electrical performance of CCF ferrites demonstrate their potential use in microwave devices. The CCF ferrites possessing soft magnetic behavior along with low magnetic and dielectric losses are promising nanomaterials for high-frequency applications too. [ABSTRACT FROM AUTHOR]

We experimentally demonstrated that heat-dissipation power driven by ferromagnetic resonance (FMR) in superparamagnetic nanoparticles of ferrimagnetic MFe2O4 (M = Fe, Mn, Ni) gives rise to highly localized incrementation of targeted temperatures. The power generated thereby is extremely high: two orders of magnitude higher than that of the conventional Néel-Brownian model. From micromagnetic simulation and analytical derivation, we found robust correlations between the temperature increment and the intrinsic material parameters of the damping constant as well as the saturation magnetizations of the nanoparticles' constituent materials. Furthermore, the magnetization–dissipation-driven temperature increments were reliably manipulated by extremely low strengths of applied AC magnetic fields under resonance field conditions. Our experimental results and theoretical formulations provide for a better understanding of the effect of FMR on the efficiency of heat generation as well as straightforward guidance for the design of advanced materials for control of highly localized incrementation of targeted temperatures using magnetic particles in, for example, magnetic hyperthermia bio-applications. [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]

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]