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The multiferroic Y-type hexaferrites BaxSr2−xMe2Fe12−yAlyO22 (Me = Zn2+, Co2+, Mg2+, etc.) have attracted much attention due to their giant magnetoelectric (ME) effect up to room temperature and low modulated magnetic field by the chemical doping control of the complex magnetic phases. However, the research of substitution between the Me ions is rare. As doping at the Me ion site can combine the advantages of both, e.g., higher magnetic ordering temperature in Co2 and stronger ME coefficient in Mg2 Y-type hexaferrites, herein, we report the stability and switching of magnetoelectric states in the Y-type hexaferrites Ba0.5Sr1.5CoMgFe11AlO22 single crystals. Our results demonstrate that substituting half of the Mg2+ with Co2+ enhances the transition temperature of the alternating longitudinal conical phase to proper screw spin order up to room temperature compared to those Mg2 Y-type hexaferrites. Simultaneous occurrence of in-plane and out-of-plane ferroelectric polarization is observed, alongside comparable spontaneous magnetization. It was found that the in-plane spin-driven polarization can be reversible below 50 K with a substantial ME coefficient α = −8000 ps/m but becomes irreversible at 100 K. This reversal in the sign of the ME coefficient signifies the transition between two distinct ME states at high temperature. The reversibility and irreversibility of spin-induced polarization are discussed within the framework of free energy based on the ferroelectric phase, which prevail in numerous Y-type hexaferrites. Our results provide insights into understanding the role of the Me ions in the magnetoelectric coupling in Y-type hexaferrites. [ABSTRACT FROM AUTHOR]

The multiferroic Y-type hexaferrites BaxSr2−xMe2Fe12−yAlyO22 (Me = Zn2+, Co2+, Mg2+, etc.) have attracted much attention due to their giant magnetoelectric (ME) effect up to room temperature and low modulated magnetic field by the chemical doping control of the complex magnetic phases. However, the research of substitution between the Me ions is rare. As doping at the Me ion site can combine the advantages of both, e.g., higher magnetic ordering temperature in Co2 and stronger ME coefficient in Mg2 Y-type hexaferrites, herein, we report the stability and switching of magnetoelectric states in the Y-type hexaferrites Ba0.5Sr1.5CoMgFe11AlO22 single crystals. Our results demonstrate that substituting half of the Mg2+ with Co2+ enhances the transition temperature of the alternating longitudinal conical phase to proper screw spin order up to room temperature compared to those Mg2 Y-type hexaferrites. Simultaneous occurrence of in-plane and out-of-plane ferroelectric polarization is observed, alongside comparable spontaneous magnetization. It was found that the in-plane spin-driven polarization can be reversible below 50 K with a substantial ME coefficient α = −8000 ps/m but becomes irreversible at 100 K. This reversal in the sign of the ME coefficient signifies the transition between two distinct ME states at high temperature. The reversibility and irreversibility of spin-induced polarization are discussed within the framework of free energy based on the ferroelectric phase, which prevail in numerous Y-type hexaferrites. Our results provide insights into understanding the role of the Me ions in the magnetoelectric coupling in Y-type hexaferrites. [ABSTRACT FROM AUTHOR]

The magnetic, elastic, and dynamical properties of L10-type FePt alloy are investigated under high pressure using first-principles calculations. The critical pressure of ferromagnetism collapse is identified as 96.7 GPa, and the alloy exhibits mechanical stability over the studied pressure range up to 120 GPa. Below the critical pressure, ductility hardly changes with pressure, and the elastic anisotropy is enhanced by pressure. The ductility and elastic anisotropy of the system show a sudden decrease beyond the critical pressure. Dynamical stabilities under ambient and high pressures are verified by phonon spectra. The alloy is dynamically stable before the critical pressure of 96.7 GPa due to spontaneous magnetization. Finally, the anisotropy of phonon density of states under high pressure is evaluated in detail, and the result indicates that the degree of anisotropy is almost independent of pressure. [ABSTRACT FROM AUTHOR]

This investigation is motivated by the surge of interest in materials, combining high spontaneous magnetization and pseudocapacitance at room temperature. Ferrimagnetic MnFe 2 O 4 offers benefits of high magnetization. However, the non-pseudocapacitive behavior, low capacitance and high resistance of MnFe 2 O 4 are limiting factors for its applications in magnetic pseudocapacitive devices. This investigation demonstrates that nearly ideal pseudocapacitive behavior can be achieved for MnFe 2 O 4 electrodes in Na 2 SO 4 electrolyte. High pseudocapacitance is observed in positive and negative potential ranges and two different charging mechanisms are proposed. High capacitance is achieved at a low impedance. The ability to achieve comparable and high areal capacitances in the positive and negative potential ranges facilitates the fabrication of a symmetric pseudocapacitive device, containing ferrimagnetic MnFe 2 O 4 as cathode and anode material for operation in enlarged voltage window of 1.6 V. The symmetric device shows capacitance of 0.92 F cm−2 at a current density of 3 mA cm−2. The individual electrodes and device show good cycling stability. The approach is based on the use of murexide and gallocyanine as redox-active dispersants and charge transfer mediators. The analysis of testing results provides an insight into the influence of chemical structure, charge and redox properties of the dispersants on the capacitive behavior. The ability to fabricate a pseudocapacitive device, containing two ferrimagnetic electrodes is promising for energy storage, water purification and novel applications based on magnetocapacitive effects. [ABSTRACT FROM AUTHOR]

Whenever the elastic energy of a solid depends on magnetic field, there is a magnetostrictive response. Field-linear magnetostriction implies piezomagnetism and vice versa. Here, we show that Mn3Sn, a non-collinear antiferromanget with Weyl nodes, hosts a large and almost perfectly linear magnetostriction even at room temperature. The longitudinal and transverse magnetostriction, with opposite signs and similar amplitude are restricted to the kagome planes and the out-of-plane response is negligibly small. By studying four different samples with different Mn:Sn ratios, we find a clear correlation between the linear magnetostriction, the spontaneous magnetization and the concentration of Sn vacancies. The recently reported piezomagnetic data fits in our picture. We show that linear magnetostriction and piezomagnetism are both driven by the field-induced in-plane twist of spins. A quantitative account of the experimental data requires the distortion of the spin texture by Sn vacancies. We find that the field-induced domain nucleation within the hysteresis loop corresponds to a phase transition. Within the hysteresis loop, a concomitant mesoscopic modulation of local strain and spin twist angles, leading to twisto-magnetic stripes, arises as a result of the competition between elastic and magnetic energies. Magnetostriction refers to the contraction or expansion of the crystal lattice of a magnetic material when a magnetic field is applied. Here, Meng et al show that Mn3Sn, a noncollinear antiferromagnet, hosts a large linear magnetostriction, which is driven by the field induced in-plane rotation of spins. [ABSTRACT FROM AUTHOR]

The intrinsic magnetization compensation behaviors of rare-earth iron garnets (REIGs) make the material promising for applications in ultrafast spin storage devices. REIG/heavy metal heterostructures such as TbIG/Pt often display two sign crossovers of anomalous Hall effect resistance with varying temperatures. One of these crossovers is attributed to the magnetization compensation of REIG, and the other to the competition between the magnetic proximity effect and the spin Hall effect. Here, we design trilayer REIG heterostructures based on two rare-earth species (Tb and Eu). We modulate the layer stacking of the TbIG/EuIG/TbIG sandwich with a fixed total thickness and explore the contributions of REIG bulk and REIG/Pt interfaces on these two crossover points. As TbIG gradually moves away from Pt, the compensation temperature shows some fluctuations. However, when TbIG is entirely out of contact with Pt, the second crossover point undergoes a change that shows REIG/Pt interface dependency. The results highlight the dominance of REIG bulk on the compensation behavior and the interface sensitivity of the second crossover point. This study provides a reference for designing controllable spintronics devices, such as magnon valve applications. [ABSTRACT FROM AUTHOR]

Reactive single-step hot-pressing at 1473 K and 35 MPa for 4 h produces dense, bulk, near single-phase, low-cost, and low-criticality Fe2Al1.15B2 and Fe2Al1.1B2Ge0.05Ga0.05 MAB samples, showing second-order magnetic phase transition with favorable magnetocaloric properties around room temperature. The magnetic as well as the magnetocaloric properties can be tailored upon Ge and Ga doping, leading to an increase in the Curie temperature T C and the spontaneous magnetization m S. The maximum isothermal entropy change Δ s T , m a x of hot-pressed Fe2Al1.15B2 in magnetic field changes of 2 and 5 T amounts to 2.5 and 5 J(kgK)−1 at 287.5 K and increases by Ge and Ga addition to 3.1 and 6.2 J(kgK)−1 at 306.5 K, respectively. The directly measured maximum adiabatic temperature change Δ T a d , m a x is improved by composition modification from 0.9 to 1.1 K in magnetic field changes of 1.93 T. Overall, we demonstrate that hot-pressing provides a much faster, more scalable, and processing costs reducing alternative compared to conventional synthesis routes to produce heat exchangers for magnetic cooling devices. Therefore, our criticality assessment shows that hot-pressed Fe-based MAB phases provide a promising compromise of material and processing costs, criticality, and magnetocaloric performance, demonstrating the potential for low-cost and low-criticality magnetocaloric applications around room temperature. [ABSTRACT FROM AUTHOR]

It is well known that the annealing process plays a key role in tuning the properties of Fe-based amorphous soft magnetic alloys. However, the optimal annealing process for a particular amorphous alloy is often difficult to determine. Here, Fe81.4B13.2C2.8Si1.8P0.8 and Fe82.2B12.4C2.8Si1.8P0.8 amorphous alloys (denoted as Fe81.4 and Fe82.2) were prepared to systematically study the effects of the annealing temperature and time on the soft magnetic properties. The results show that the optimum annealing temperature ranges of the Fe81.4 and Fe82.2 amorphous alloys were 623 K to 653 K and 593 K to 623 K, and their coercivity (Hc) values were only 2.0–2.5 A/m and 1.3–2.7 A/m, respectively. Furthermore, a characteristic temperature Tai was obtained to guide the choosing of the annealing temperature at which the dBs/dT begins to decrease rapidly. Based on the theory of spontaneous magnetization, the relationship between Tai and the optimum annealing temperature ranges was analyzed. When the annealing temperature was higher than Tai, the effect of the internal magnetic field generated by spontaneous magnetization on the relaxation behavior was significantly reduced, and the alloys exhibited excellent soft magnetic properties. It is worth indicating that when annealed at 603 K (slightly higher than Tai), the Fe82.2 amorphous alloys exhibited excellent and stable soft magnetic properties even if annealed for a long time. The Hc of Fe82.2B12.4C2.8Si1.8P0.8 amorphous alloys was only 1.9 A/m when annealed at 603 K for 330 min. This value of Tai is expected to provide a suggestion for the proper annealing temperature of other amorphous soft magnetic alloys. [ABSTRACT FROM AUTHOR]

In this article, we present a study of the properties of two-dimensional (2D) derivatives of MAX phases, namely W 2 XT 2 (X = C, N; T = O, F) MXenes, which have become hot spots of research for their intriguing physical properties. In pursuing this first-principles study, we realized W 2 X pristine MXene by eliminating the Ga atomic layer from the W 2 GaX MAX phase, which is then functionalized with oxygen and fluorine. These materials exhibit electronic states above the Fermi level primarily of W- d nature, indicating their metallic nature similar to the parent MAX phases. The distribution of up and down spin electronic states is highly symmetrical, depriving the W 2 XT 2 MXenes of spontaneous magnetization. They demonstrated prominent optical properties where the W 2 NF 2 exhibits approximately 70% reflection of infrared (IR) light, while W 2 CF 2 reflects around 47%. On the contrary, W 2 NO 2 and W 2 CO 2 reflect 33% and 20% of the incident IR light, respectively. At an energy of 0 eV, the refractive indices recorded for W 2 CF 2 , W 2 CO 2 , W 2 NF 2 , and W 2 NO 2 were 5.11, 2.29, 8.56, and 3.47, respectively. When exposed to IR light, they showed remarkable ultraviolet (UV) light absorption of 23.62 × 104 cm−1 and 20.71 × 104 cm−1 for W 2 NF 2 and W 2 CF 2 , respectively. The absorption of IR light by W 2 CO 2 and W 2 NO 2 was relatively smaller, with values of 12.52 × 104 cm−1 and 8.30 × 104 cm−1, respectively. The interesting optical characteristics of the W 2 XT 2 MXene make them promising for utilization in advanced optical devices. • Exploration of Novel Tungsten-based MXenes. • Constituents and Functional Groups Influence. • Intriguing Electronic Properties. • Symmetrical Spin Electronic States. • Interesting Optical Characteristics. [ABSTRACT FROM AUTHOR]

The measurement of transport current density is significant for investigations on improving the properties of RE Ba2Cu3O7− x (RE BCO, where RE refers to rare-earth elements)-coated conductors (CCs). In this work, a protocol for mapping the transport current density of CC by magneto-optical imaging (MOI) is presented. A calibration method is developed based on the non-linear physical governing function for the MOI indicator, in which only two parameters are determined, i.e. the anisotropic magnetic field BA, and cMs, which is the multiplication of the constant c related to the thickness of the MOI indicator and the spontaneous magnetization Ms. The experimental results also showed that they were independent of the optical measure condition but dependent on temperature, making this calibration method comparative among different utilizers. The numerical results clearly manifested that the selected window size of the magnetic field around a long superconducting tape is closely related to the error of the reconstructed current density. A large window size of the magnetic field is needed to precisely reconstruct the transport current density. For actual MOI testing, a practical approach to extend the magnetic field data outside the MOI window was realized by fitting with a power function according to Ampere's law, through which the false current density outside the sample is automatically suppressed to a large extent. On this basis, the mapping of the transport current density in the CC sample was achieved. It is believed that this work will improve MOI for a more precise measurement of the transport current density for long superconducting strips. [ABSTRACT FROM AUTHOR]

We have already reported some electroplated magnetic films using aqueous solutions. In the present study, we proposed a fabrication process for electroplated soft magnetic films (Ni films) using gel electrolytes. We added gelatin to the plating baths and confirmed that adding 22 g/L of gelatin enabled us to obtain gel electrolytes. Using the gel electrolytes, we electroplated Ni films and evaluated their structural and magnetic properties. From the evaluation of magnetic properties, we confirmed spontaneous magnetization of the Ni films prepared from the gel electrolyte. For obtaining thick Ni films (>1 μm), we investigated stirring the gel electrolyte during plating. As a result, we found that stirring increased the thickness, and our result suggests that stirring the gel electrolyte is useful to increase the deposition rate. In our experimental conditions, the deposition rate of the plating process was ∼0.25 μm/min. From XRD analysis, the structure of Ni films for gel electrolytes was oriented in the fcc (220) plane and slightly different from that for liquid electrolytes. From these results, we found that soft magnetic films could be obtained from the gel electrolyte and that gel plating is one of the attractive fabrication processes of the thick films. [ABSTRACT FROM AUTHOR]

The variation of temperature modifies the magnetic behavior of ferromagnetic cores which may affect the performance of electrical equipment. Therefore, it is imperative to develop a temperature-dependent hysteresis model to precisely calculate electromagnetic characteristics of electrical equipment. In this paper, a Temporal Convolutional Network (TCN) in combination with the Play operator is developed. The proposed model incorporates the temperature-dependent spontaneous magnetization intensity as the model input to introduce the temperature effect. To enhance the accuracy of model training outcomes, the Bayesian optimization approach for automatically selecting network model parameters is provided. The results show that the proposed model can accurately predict the hysteresis characteristics of materials under varying temperature and frequency conditions. [ABSTRACT FROM AUTHOR]

This investigation addresses increasing interest in advanced composite materials, combining capacitive properties and spontaneous magnetization for energy storage applications in supercapacitors. The capacitive properties of ferrimagnetic NiFe2O4 (NFO) spinel nanoparticles with magnetization of 30 emu g−1 were enhanced using high-energy ball-milling and the use of advanced dispersant, which facilitated charge transfer. NFO electrodes with an active mass of 40 mg cm−2 showed a capacitance of 1.46 F cm−2 in 0.5 M Na2SO4 electrolyte in a negative potential range. The charging mechanism in the negative potential range in Na2SO4 electrolyte was proposed. NFO was combined with conductive polypyrrole polymer for the fabrication of composites. The analysis of the capacitive behavior of the composites using cyclic voltammetry, chronopotentiometry and impedance spectroscopy at different electrode potentials revealed synergy of contributions of NFO and PPy. The highest capacitance of 6.64 F cm−2 was obtained from cyclic voltammetry data. The capacitance, impedance, and magnetic properties can be varied by variation of electrode composition. Composite electrodes are promising for application in anodes of asymmetric magnetic supercapacitors for energy storage and magnetically enhanced capacitive water purification devices. [ABSTRACT FROM AUTHOR]

In artificially tilted multilayers comprising two different conductors that are alternately and obliquely stacked, transverse thermoelectric conversion occurs, in which charge and heat currents are interconverted in the orthogonal direction. Although transverse thermoelectric conversion also occurs in homogeneous materials as an intrinsic transport phenomenon owing to the effects of magnetic fields, magnetization, and spins on conduction carriers, such magneto‐thermoelectric effects are investigated independently of thermoelectrics for artificially tilted multilayers. Here, this study shows that the synergy of these different principles improves the performance of transverse thermoelectric conversion. Using lock‐in thermography techniques, transverse thermoelectric conversion processes are visualized in artificially tilted multilayers and the experiments clarify how nonuniform charge currents are converted into orthogonal heat currents. Through the measurements of temperature change under magnetic fields, the contributions of the magneto‐thermoelectric effects are quantified in the artificially tilted multilayers and magnetically enhanced hybrid transverse thermoelectric cooling is demonstrated. By replacing one of the conductors in the multilayer with permanent magnets, the same functionality is obtained even in the absence of magnetic fields, paving the way for the creation of "thermoelectric permanent magnets" that exhibit efficient transverse thermoelectric conversion together with spontaneous magnetization. This study provides a new material design guideline for transverse thermoelectrics. [ABSTRACT FROM AUTHOR]

This investigation delves into the complex interaction at metal-semiconductor interfaces, highlighting the magnetic proximity effect in Ni/Si interfaces through systematic X-ray magnetic circular dichroism (XMCD) studies at Ni and Si edges. We analyzed two Ni/Si heterostructures with differing semiconductor doping, uncovering a magnetic proximity effect manifesting as equilibrium magnetization in the semiconductor substrate induced by the adjacent Ni layer. Our results display distinct magnetization signs corresponding to the doping levels: low-doped samples show parallel alignment to the Ni layer, while high-doped samples align antiparallel, indicating a nuanced interplay of underlying magnetization mechanisms. These findings pinpoint the roles of electron tunneling and exchange splitting modification in the magnetization behavior. The study enriches the understanding of ferromagnetic-semiconductor interface behavior, setting a precedent for the design of advanced spintronic devices that leverage the nuanced magnetic properties of these hybrid systems. [ABSTRACT FROM AUTHOR]

While most studies in disordered rock salt cathode materials focus on synthesis and electrochemical investigation, detailed investigations on their optical and thermodynamic properties are a matter of interest. Here, we report on complementary measurements of transient absorption spectroscopy, thermodynamic, and dielectric properties for Li1.3Nb0.3Fe0.4O2 (LNFO) disordered rock salt Li-excess. The structure was studied using powder x-ray diffraction and scanning electron microscopy, which showed the fine crystallization of LNFO. The ultra-fast laser spectroscopy is used to study the dynamics of charge carriers and electron–phonon coupling in the system. Our thermodynamic measurements have revealed a magnetically ordered phase with small spontaneous magnetization. The dielectric properties of LNFO illustrate high permittivity with losses at low frequencies. Furthermore, the behavior of the dielectric modulus and AC conductivity vs temperature and frequency were discussed. [ABSTRACT FROM AUTHOR]

In this article, we have studied the critical behaviour at the ferromagnetic–paramagnetic phase transition in Tb2Rh3Ge alloy. By exploiting the Landau theory, isothermal magnetization M(H, T) curves near the ferromagnetic–paramagnetic phase transition have been generated. The optimized critical exponents, through an iterative program based on the Kouvel–Fisher method, were found to be as: γ = 1.003 ; β = 0.348 . These critical exponents are unambiguous and reasonable, but they do not match with the conventional universal classes. Based on the combination of the Arrott–Noakes equation and the Landau model, the magnetic entropy change curves have been successfully simulated. [ABSTRACT FROM AUTHOR]

We analyse the Blume–Emery–Griffiths (BEG) model on the lattice Z d on the ferromagnetic-antiquadrupolar-disordered (FAD) point and on the antiquadrupolar-disordered (AD) line. In our analysis on the FAD point, we introduce a Gibbs sampler of the ground states at zero temperature, and we exploit it in two different ways: first, we perform via perfect sampling an empirical evaluation of the spontaneous magnetization at zero temperature, finding a non-zero value in d = 3 and a vanishing value in d = 2 . Second, using a careful coupling with the Bernoulli site percolation model in d = 2 , we prove rigorously that under imposing + boundary conditions, the magnetization in the center of a square box tends to zero in the thermodynamical limit and the two-point correlations decay exponentially. Also, using again a coupling argument, we show that there exists a unique zero-temperature infinite-volume Gibbs measure for the BEG. In our analysis of the AD line we restrict ourselves to d = 2 and, by comparing the BEG model with a Bernoulli site percolation in a matching graph of Z 2 , we get a condition for the vanishing of the infinite-volume limit magnetization improving, for low temperatures, earlier results obtained via expansion techniques. [ABSTRACT FROM AUTHOR]

Introduction/purpose: Quantum field theory techniques are able to describe precisely, inter alia, collective phenomena of statistical and solid state physics. Method: The path integral method with a Wick rotation shows its complete analogy with the partition function of statistical mechanics. Results: The Landau–Ginzburg phenomenology successfully describes collective phenomena such as spontaneous magnetization and superconductivity. Conclusions: Symmetry breaking phenomena could give macroscopic results. [ABSTRACT FROM AUTHOR]

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The ilmenite-type CoVO3 undergoes an antiferromagnetic transition below 140 K, and the tetravalent vanadium ions form V–V dimers below 550 K. This paper presents the magnetic spin structure and the phase transition induced by a magnetic field in CoVO3. Neutron powder diffraction at 50 K reveals that the spins of Co2+ arrange in a zigzag order on the honeycomb lattice with no external magnetic field. This magnetic spin structure does not exhibit spontaneous magnetization, corroborating previous magnetic measurements. Magnetization measurements in a pulsed-magnetic field revealed a transition to a weak-ferromagnetic phase at 37 T (100 K) and above 50 T (4.2 K), with spontaneous magnetization approximating 0.3–0.5 μB/f.u. This phase transition could potentially be attributed to a transition to a canted antiferromagnetic phase, which is brought about by the reduction in structural symmetry due to magnetostriction. [ABSTRACT FROM AUTHOR]

The ilmenite-type CoVO3 undergoes an antiferromagnetic transition below 140 K, and the tetravalent vanadium ions form V–V dimers below 550 K. This paper presents the magnetic spin structure and the phase transition induced by a magnetic field in CoVO3. Neutron powder diffraction at 50 K reveals that the spins of Co2+ arrange in a zigzag order on the honeycomb lattice with no external magnetic field. This magnetic spin structure does not exhibit spontaneous magnetization, corroborating previous magnetic measurements. Magnetization measurements in a pulsed-magnetic field revealed a transition to a weak-ferromagnetic phase at 37 T (100 K) and above 50 T (4.2 K), with spontaneous magnetization approximating 0.3–0.5 μB/f.u. This phase transition could potentially be attributed to a transition to a canted antiferromagnetic phase, which is brought about by the reduction in structural symmetry due to magnetostriction. [ABSTRACT FROM AUTHOR]

Through micromagnetic simulations, this work analyzes the possibility of using an array of magnetic nanospheres hosting Bloch points (BPs) to compose a system with the features of a magnetic trap (MT). We show that a BP can be nucleated as a metastable configuration in a wide range of the nanosphere radius compared to a quasi-uniform and vortex state. We also show that the stabilized BP generates a quadrupolar magnetic field outside the nanosphere. Based on this fact, we analyze the field profile of different arrays of these nanospheres, showing that the obtained magnetic field profiles share the needed features to compose MTs. Some highlights of using an array of Bloch point nanospheres in MTs rely on the magnetic field gradients achieved, which are orders of magnitude higher than similar standard systems, and allow three-dimensional trapping. Our results could be useful in trapping particles through the intrinsic magnetization of ferromagnetic nanoparticles while avoiding the commonly used mechanisms associated with Joule heating. [ABSTRACT FROM AUTHOR]

Within the framework of the phenomenological concepts of two-component electrical conductivity, a correlation analysis of the temperature behavior of the kinetic and magnetic characteristics of the high-entropy Al0.5CoCuCrNiFe alloy in the range of Т ∼ 210–170 K was carried out. It was shown that the reason for the previously discovered anomalies in these characteristics is conversion transformations in the system of charge carriers. The "driving force" of the transformations, apparently, is a non-conformal change with temperature in the positions of the alloy atoms, which differ in size, mass, and electronic structure. This leads to the deformation of the Brillouin zones and modification of the Fermi surface. It has been shown for the first time that the spontaneous magnetization (Is) of alloys of the AlCoCuCrNiFe family contains electronic Ise and hole Ish components. In accordance with Bloch's "T3/2" law, we concluded that the exchange interaction integral J in these alloys is also two-component. The agreement of the obtained experimental data with the results of "mechanical spectroscopy" of identical samples of Al0.5CoCuCrNiFe alloy is demonstrated. [ABSTRACT FROM AUTHOR]

"Do Carroll particles move?" The answer depends on the characteristics of the particle such as its mass, spin, electric charge, and magnetic moment. A massive Carroll particle (closely related to fractons) does not move; its immobility follows from Carroll boost symmetry which implies dipole conservation, but not conversely. A massless Carroll particle may propagate by following the Hall law, consistently with the partial breaking of the Carroll boost symmetry. The framework is extended to Carroll field theory. In d = 2 space dimensions, the Carroll group has a two-fold central extension which allows us to generalize the dynamics to massive and massless particles, including anyons. The anyonic spin and magnetic moment combine with the doubly-extended structure parametrized by two Casimir invariants interpreted as intrinsic magnetization and non-commutativity parameter. The extended Carroll particle subjected to an electromagnetic background field moves following a generalized Hall law which includes a Zeeman force. This theory is illustrated by massless, uncharged anyons with doubly-centrally extended structure we call exotic photons, which move on the horizon of a Black Hole, giving rise to an anyonic spin-Hall Effect. [ABSTRACT FROM AUTHOR]

In recent years, spin Hall magnetoresistance (SMR) has emerged as an efficient way to probe the spontaneous magnetization state in ordered magnetic systems by electrical current. Less known is its versatility as a probe of materials that do not possess spontaneous magnetization, such as in paramagnets. In this work, SMR is used to probe paramagnetic NdGaO3 (NGO), a rare earth oxide, possessing a sizable spin–orbit interaction (L = 6). NGO has not been investigated earlier for its efficiency in propagating spins. We have performed extensive temperature and angle dependent-magnetoresistance (ADMR) studies along different crystallographic axes in NGO, using platinum (Pt) as a spin injector and a detector and utilizing (inverse) spin Hall effect. We find a close correlation between the temperature dependence of the ADMR response with magnetization in NGO and a linear current bias dependence of the ADMR amplitudes. These are characteristics of the SMR effect in Pt/NGO, arising from the torque acting on localized moments in NGO and considering crystal field induced intermultiplet transitions with temperature. Control experiments on Pt/SrTiO3 and Pt/SiO2 devices were also carried out in order to validate the observed SMR response in the Pt/NGO bilayer and to rule out magnetoresistive contributions from Pt. [ABSTRACT FROM AUTHOR]

In the present paper we propose a microscopic model to study the multiferroic properties of Bi 2 Fe 4 O 9 nanoparticles. The spontaneous magnetization M s increases with decreasing nanoparticle size. M s is shape dependent. It is larger for cylindrical than for spherical nanoparticles. M s increases with increasing Co and Ho concentration, whereas by Mn doping it decreases. These tunable magnetic properties can be widely applied in spintronics. The polarization P s increases also with decreasing nanoparticle size. Mn ion doping leads to increase of P s , the phase transition temperature T C and the dielectric constant and so to enhanced electric and dielectric properties of Bi 2 Fe 4 O 9 nanoparticles. Applying an external magnetic field P s is enhanced, which is indirect evidence for a strong magnetoelectric coupling. The specific heat C p shows an anomaly at the Neel temperature T N which vanishes by applying an external magnetic field. The band gap energy E g decreases with increasing Ti, Co and Ho dopants whereas by Mn doping E g increases. [ABSTRACT FROM AUTHOR]

This paper presents a detailed study in the critical region around the Curie temperature to determine the universality class of the Sm 2 Ni 17 intermetallic compound. The magnetocaloric effect has been studied on the basis of experimental measurements of magnetization. Maxwell's relation and a phenomenological model are employed to find the change in magnetic entropy. The compound Sm 2 Ni 17 presents a variation in entropy with a moderate maximum and a wide range of operating temperatures. Numerous approaches have been used to explore the spontaneous magnetization behaviour and inverse of the susceptibility, including the modified Arrott technique, the Kouvel–Fisher approach, and the fitting of the critical isotherm. The scaling hypothesis has been used to confirm the validity and interdependence of the critical exponents associated with these phenomena. [ABSTRACT FROM AUTHOR]

In this paper, we have studied the critical behavior at the paramagnetic ferromagnetic (PM-FM) phase transition (PT) in GdTbHoErLa (GTHEL) alloy. Near the PM-FM PT, the usefulness of the Landau theory leads to generate isothermal magnetizations M (H , T) . Through an iterative program based on the Kouvel–Fisher method, the critical exponents have been optimized. They were found to be γ = 1.04 and β = 0.82 . Thus, the exponent at the Curie temperature δ was estimated to be 2.27 . Moreover, the critical parameters are unambiguous and reasonable, but they are not matching with the conventional universality classes. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) are a class of two-dimensional (2D) anionic materials that exhibit remarkable chemical versatility, making them ideal building blocks in the design of complex multifunctional materials. In this line, a NiFe-LDH is probably one of the most important LDHs due to its interesting electrochemical and magnetic properties. However, no direct magnetic measurements of exfoliated NiFe-LDH nanosheets have been reported so far. Herein, we synthesize a hybrid NiFe-LDH family through anion exchange reactions using surfactant molecules in order to increase the interlayer space (ranging from 8 to 31.6 Å), minimizing the interlayer dipolar interactions. By intercalation with octadecylsulphate, we have managed to obtain the largest interlayer space reported for a NiFe-LDH while keeping a similar size, morphology and composition. This wide interlayer separation results in a decrease in temperatures at which spontaneous magnetization (TM) occurs and the blocking temperature (TB), as well as a decrease in the coercive fields (HC). In fact, an abrupt drop in all these magnetic parameters above 30 Å interlayer distance is observed, evidencing complete magnetic decoupling of the layers. We have further validated our molecular engineering approach by characterizing the hybrid materials by Mössbauer spectroscopy and comparing the magnetic analysis results with those for a liquid phase exfoliated NiFe-LDH sample. Overall, this work provides fundamental insights into the magnetism of NiFe-LDHs, showing the potential of molecular engineering for designing hybrid layered magnetic materials approaching the 2D magnetic limit. [ABSTRACT FROM AUTHOR]

The influence of the surface modification on the magnetism of 4–14 nm sized core and core/shell gallium ferrites obtained by different preparation methods (Massart's and thermal decomposition from acetylacetonates) was studied. The physical properties of GaxFe3-xO4 were investigated in a wide range of Ga admixtures 0 ≤ x ≤ 1.5. Ga ions location at 8a or/and 16d positions of a spinel structure depends on the synthesis method and has a pronounced effect on the superparamagnetic properties of nanoparticles. Magnetization and Mössbauer experiments show the dominant superparamagnetic contribution for the nanoparticles with x > 0.8 with the blocking temperature TB significantly below 200 K. Surface-modified nanoferrites disclosed spontaneous magnetization that does not exceed 60 emu/g. [ABSTRACT FROM AUTHOR]

In the present work we report low temperature magnetic properties of Ni92−xAlxCr8 alloys. It is found that the Curie temperature and spontaneous magnetization (MSP) get suppressed around xC ≈ 7. From the analysis of the temperature and field dependent magnetization data we have obtained high value of Rhodes–Wohlfarth ratio, which indicates the weak itinerant ferromagnetic behavior for samples below xC. This is further supported by analysing the temperature variation of MSP in the framework of spin fluctuations, SCR theory. Furthermore, the Ginzburg-Landau formalism-based on spin fluctuation theory revealed that the contribution of spin fluctuations at low temperature increases as we approach xC. [ABSTRACT FROM AUTHOR]

The relevant approximate spontaneous magnetization relations for the simple-cubic and body-centered-cubic Ising lattices have recently been obtained analytically by a novel approach that conflates the Callen–Suzuki identity with a heuristic odd-spin correlation magnetization relation. By exploiting this approach, we study an approximate analytic spontaneous magnetization expression for the face-centered-cubic Ising lattice. We report that the results of the analytic relation obtained in this work are nearly consistent with those derived from the Monte Carlo simulation. [ABSTRACT FROM AUTHOR]

Based on the shooting method, we numerically investigate the properties of holographic paramagnetism-ferromagnetism phase transition in the presence of higher-order Gauss–Bonnet (GB) correction terms on the gravity side. On the matter field side, however, we consider the effects of Power-Maxwell (PM) nonlinear electrodynamics on the phase transition of this system. For this purpose, we introduce a massive 2-form coupled to PM field, and neglect the effects of 2-form fields and gauge field on the background geometry. We observe that increasing the strength of both the power parameter q and GB coupling constant α decreases the critical temperature of holographic model, and leads to the harder formation of magnetic moment in the black hole background. Interestingly, we find out that at low temperatures, the spontaneous magnetization and ferromagnetic phase transition happen in the absence of external magnetic field. In this case, the critical exponent for magnetic moment has the mean field value, 1 / 2 , regardless of the values of q and α. In the presence of external magnetic field, however, the magnetic susceptibility satisfies the Curie–Weiss law. [ABSTRACT FROM AUTHOR]

The critical behavior for the second-order ferromagnetic paramagnetic phase transition Ni50Mn29Ga20.8Tb0.2 alloy is studied. The values of the critical exponents were found to be γ = 1.05 , β = 0.45 and are close to the ones described by the mean-field model. Using the Arrott–Noakes equation of state with these γ and β values, the Curie temperature was successfully calculated. The isothermal magnetization M and magnetic entropy change - Δ S M curves were simulated using the Arrott–Noakes equation, the Landau theory and a mean field model. [ABSTRACT FROM AUTHOR]

Abstract—The magnetic properties of Fe3O4–Fe3 –xTixO4 composites synthesized by various methods were simulated based on the model of an ensemble of magnetostatically interacting particles. The results are in good agreement with the hysteresis characteristics of the samples calculated earlier in the framework of the model of chemically heterogeneous two-phase particles. It is shown that the used approach is also applicable to the samples consisting mainly of superparamagnetic particles in which the saturation remanent magnetization is provided by the particles blocked due to the magnetostatic interaction. [ABSTRACT FROM AUTHOR]

In the present paper, the magnetization processes in amorphous alloys based on iron are discussed in detail. Our main goal was to measure the stabilization energy connected with the presence of microvoids (frozen during rapid cooling from the liquid phase) and to determine the interaction energy of relaxators with spontaneous magnetization vector (the so-called wN Neel) for amorphous Fe78Si13B9 alloys. A structural analysis of the alloys using X-ray measurements at the subsequent stages of crystallization was also performed. [ABSTRACT FROM AUTHOR]