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ABSTRACT Sr2YRuO6 is a material that provides an ideal platform for studying magnetic frustration in three‐dimensional geometries. Herein, we combine Raman spectroscopy and density functional theory calculations to establish connections between the lattice dynamics and magnetic states in Sr2YRuO6 single crystals. The x‐ray diffraction profiles reveal that Sr2YRuO6 possesses an ordered double‐perovskite structure with distorted monoclinic symmetry. Three magnetic phase transitions are observed and linked to the presence of weak ferromagnetism at 135 K and short‐ and long‐range antiferromagnetic orderings at 32 and 26 K. The oxygen‐octahedron antistretching and stretching modes, observed at 570 and 766 cm−1, exhibit anomalies near the magnetic phase transition temperatures, indicating an intriguing interplay between the lattice and spin degrees of freedom. Their spin–phonon coupling constants of 0.7 cm−1 reflect the weak spin–lattice interactions in Sr2YRuO6. [ABSTRACT FROM AUTHOR]

2D van der Waals antiferromagnets, MPX3 (M = Fe, Cr, and Mn; X = S and Se), are promising candidates for spintronic devices owing to their advantageous structural and magnetic properties. However, their insulating properties and high‐field requirements make magnetic characterization in 2D MPX3 challenging. Fortunately, the correlation between magnetic and optical properties in MPX3 crystals provides an optical approach to investigate their magnetic properties. Herein, Cr atoms are used to modulate the magnetic properties of MnPS3, with photoluminescence (PL) techniques used to investigate the effect of doping. Results show a new PL peak in Cr‐doped MnPS3 crystals, with distinct temperature‐dependent PL behaviors compared to the undoped host. The influence of doping concentration, temperature, and thickness on PL is investigated. Surprisingly, even when long‐range magnetic ordering is completely disrupted, the temperature‐dependent PL properties of Cr‐doped MnPS3 (CrxMn1 − xPS3) still follow the Néel transition behavior of MnPS3, showing the presence of local antiferromagnetism in CrxMn1 − xPS3. This study further substantiates the correlation between magnetic ordering and PL in MnPS3 and demonstrates that PL is a powerful tool for detecting weak local magnetism in 2D MPX3 crystals. [ABSTRACT FROM AUTHOR]

This work attempted to study the effects of the solidification behavior on the magnetic and magnetocaloric properties of stoichiometric Ni50Mn34In16 Heusler alloy. In this respect, the samples with two different diameters of 2 mm (D2 sample) and 8 mm (D8 sample) were prepared by suction casting technique. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and magnetic force microscopy (MFM) were employed to identify the structure, microstructure, and magnetic domain distribution of the samples. Also, phase transformation behavior was characterized using differential scanning calorimetry (DSC) across a temperature range of 200–350 K. Thermo-magnetic properties of samples were evaluated using SQUID Quantum Design MPMS®3 during heating and cooling at the temperature range of 175–350 K at the constant magnetic field of 2 T. Moreover, the magnetic and magnetocaloric properties of the samples were analyzed using the cryostat-equipped VSM around the magnetic phase transition temperature under a magnetic field up to 1.75 T. Based on the results obtained, it is shown that an increase in the sample diameter leads to an increase in the Curie temperature. Furthermore, it was concluded that the magnetocaloric properties such as magnetic entropy change ( Δ S M ), adiabatic temperature change ( Δ T ad ), and refrigerant capacity ( RC ) parameters improved with an increase in the sample diameter through the microstructural refinement and enhancing the atomic ordering. Specifically, the maximum values of the Δ S M , RC , and Δ T ad for the D8 sample are estimated to be 3.04 J/kg K, 109.83 J/kg, and 0.94 K, respectively. [ABSTRACT FROM AUTHOR]

We studied magnetic phase transitions near the Curie temperature in the ferrite material with the composition using thermomagnetometric analysis and methods for recording the temperature dependences of initial magnetic permeability and specific electrical resistivity . The study provides a description of the equipment used and the key features of the experimental methods under consideration. During thermomagnetometric analysis in the cooling phase, it has been found that the temperature at which the material completes its transition to the ferrimagnetic state corresponds to the inflection point on the curve and the break point on the dependence graph. The established interaction between the parameters of transition processes may be useful for more accurate determination of the Curie temperature in ferrites. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Chinese Society of Rare Earths is the property of Editorial Department of Journal of the Chinese Society of Rare Earths and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rare earth elements possessing a diverse range of optical, electrical, and magnetic properties has attracted more attention. In the present work, GdClWO 4 compound with monoclinic structure was prepared, the structure, magnetism and magnetocaloric effect (MCE) were investigated. The magnetic phase transition temperature (T N), magnetic ground state and maximum magnetic entropy change ( − Δ S M max) were derived from magnetization measurements. Both first principles calculation and experimental results suggest that the compound displays antiferromagnetic (AFM) interactions, with a magnetic transition occurring at 0.6 K, shifting from a paramagnetic (PM) state to an AFM state. The − Δ S M max is up to 35.2 J kg−1 K−1 (205.9 mJ cm−3 K−1) for GdClWO 4 at T = 1.3 K under a magnetic field change of 0–50 kOe. In particular, the volumetric magnetic entropy change still remains 83.1 mJ cm−3 K−1 at 0.5 K and μ 0 Δ H = 20 kOe, which is almost twice as much as that of commercial refrigerant Gd 3 Ga 5 O 12 (GGG) under μ 0 Δ H = 20 kOe, establishing GdClWO 4 compound as a potential candidate for cryogenic refrigeration applications. [ABSTRACT FROM AUTHOR]

In this study, polycrystalline samples of Pr2Mn2O6 (parent phase) and Pr1.5A0.5Mn2O6 (A = Mg, Ba) were prepared using the high-temperature solid-phase reaction method. The effects of Mg and Ba doping on magnetocaloric properties and critical behavior of the parent phase were systematically investigated. Under a magnetic field of 7 T, the relative cooling power (RCP) values of Pr2Mn2O6, Pr1.5Mg0.5Mn2O6, and Pr1.5Ba0.5Mn2O6 were approximately 483.46 J·kg−1, 428.22 J·kg−1, and 479.88 J·kg−1, respectively. The critical behavior analysis revealed that the parent phase showed short-range exchange interactions, while Pr1.5A0.5Mn2O6 (A = Mg, Ba) exhibited long-range exchange interactions. The temperature dependence of the order parameter n was studied under different magnetic fields, confirming the phase transition types and validating the accuracy of the critical exponents obtained. The research findings suggest that both the parent phase and Ba-doped ceramics at the A-site hold promise as magnetic refrigeration materials. [ABSTRACT FROM AUTHOR]

Multiferroic materials are an exceptional class of magnetic materials where long-range magnetic and ferroelectric orders coexist, thus provoking the researchers' interest from both basic and practical points of view. The magnetoelectric multiferroics are materials that combine coupled electric and magnetic dipoles. Recently, research has focused on the occurrence of the magnetoelectric effect in some hexagonal ferrite types and the possibility of their use as single-phase multiferroic and magnetoelectric materials. For many years, various hexaferrites have been intensively studied as materials for permanent magnets, high-density recording media, microwave devices, biomedical applications, etc. The magnetic structure and especially the specific magnetic spin arrangement under certain conditions proved to be key factors for the realization of magneto-electric phases in hexaferrites. Here some recent advances in our studies of the magnetic phase transitions in the Y-type hexaferrites are overviewed. In particular, the influence of the replacement of non-magnetic Me2+ cations with magnetic cations and of magnetic Fe3+ cations with non-magnetic ones on the magnetic properties and occurring magnetic phase transitions in Y-type hexaferrites are exemplified with Ba0.5Sr1.5Zn2Fe12O22. [ABSTRACT FROM AUTHOR]

The influence of the structure of nickel-zinc ferrite powders on the behavior of magnetic phase transitions is studied in the Curie point region. The samples with a controlled set of microstresses and sizes of coherent scattering regions are prepared by dry milling of the synthesized ferrites in a ball mill at the rates of 500, 1000, 1500 rev/min for 15, 30, and 60 min. Their structure is examined by the method of X-ray diffraction. An analysis of the magnetic phase transitions in the Curie temperature region is performed using thermogravimetry in a constant magnetic field (thermomagnetometry). The regularities of variations of the powder structure parameters as a function of the frequency-time dry milling modes are identified. A linear regression dependence of the amplitude of the weight section in the thermogravimetry curve in the Curie point region on the value of microstresses and the size of coherent scattering regions is revealed. The findings allow taking account of the influence of these structural characteristics on the shape of the thermograms in the region of magnetic phase transitions and provide a more precise interpretation of the thermomagnetometric results. [ABSTRACT FROM AUTHOR]

The crystal structure, magnetic phase transitions and magnetocaloric effect of DyCo2−xGex (x = 0.0–0.2) compounds were studied. X-ray diffraction coupled with Rietveld analysis shows that all DyCo2−xGex samples maintain the cubic Laves structure (MgCu2-type, Fd-3 m space group), and the lattice parameter increases as x increases. Under an applied field change of 0–5 T, the maximum magnetic entropy change of DyCo2−xGex (x = 0.0, 0.05, 0.15 and 0.2) compounds are 10.4, 10.3, 7.3 and 6.3 J/kg K, and the values of relative cooling power are 290.6, 309.6, 290.4 and 271.8 J/kg, respectively. According to Arrott plots and the Inoue-Shimizu model, DyCo2 and DyCo1.95Ge0.05 compounds still maintain the first-order magnetic phase transition. But when the Ge content exceeds 0.05, a magnetic phase transition from first-order to second-order occurs. Magnetic measurement reveals that the Ge content increases the Curie temperature from 151 (for x = 0.0) to 179 K (for x = 0.2). This suggests that the DyCo2−xGex compounds are candidate materials for cryogenic magnetic cooling, which can be used in natural gas liquefaction, biological organ storage in medicine and quantum computer heat dissipation. [ABSTRACT FROM AUTHOR]

Copyright of Rare Metals is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

2D magnets have recently drawn enormous interest. As an air‐stable A‐type van der Waals antiferromagnet (AFM), CrSBr has attracted great attention but has also led to controversies about its large‐span ordering temperatures. Herein, a systematic study of the magnetic phase transition in single‐crystalline CrSBr with ultrahigh‐quality through surface‐sensitive X‐ray magnetic linear dichroism and X‐ray magnetic circular dichroism measurements combined with vibrating sample magnetometry for characterization of bulk magnetization is reported. The interlayer AFM order of both surface and bulk CrSBr is revealed to maintain a similar Néel temperature within the range of 132–142 K. However, the intralayer ferromagnetic (FM) order of surface CrSBr is found to sustain up to ≈238 K, 70 K higher than the value obtained from the bulk CrSBr, demonstrating a dramatically different surface and bulk Curie temperature in CrSBr. Moreover, a half‐filled t2g electronic state for Cr3+ ions with magnetic moment of ≈3 µB/Cr in CrSBr is clearly identified. These results enrich the understanding of the electronic structure and magnetism in CrSBr, providing this material as a promising building block for future spintronic devices. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Chinese Society of Rare Earths is the property of Editorial Department of Journal of the Chinese Society of Rare Earths and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, La0.75Sr0.25Mn1−xCoxO3 (x = 0, 0.1, 0.2) samples were synthesized using a high-pressure heat treatment method, and their magnetic properties and critical phase transition behaviors were systematically investigated. The prepared samples exhibited excellent single-phase characteristics with space group R 3¯ c. As the Co content increased, TC decreased from 325 to 211 K. In a 7 T magnetic field, the RCP values of the samples increased from 364.52 to 384.66 J·kg−1, significantly enhancing the cooling efficiency of the samples. The three samples exhibited a second-order phase transition, indicating a relatively small hysteresis in the system. The critical exponents were obtained by MAPs and K-F method. These results indicate that with an increase in Co doping, the β values also increase, suggesting that Co doping facilitates the establishment of long-range ferromagnetic order in the three samples.

The Ta/Dy/Ta nanostructures are fabricated by high-vacuum magnetron sputtering. Resistance and longitudinal magnetoresistance are measured. It is shown that the observed the effect of magnetic field on resistance are due to the competition of two effects of different nature. The negative isotropic magnetoresistance in the dysprosium layer is due to the alignment of local magnetic moments in the direction of the applied magnetic field. The positive longitudinal magnetoresistance in tantalum layers is caused by a change in the conditions of scattering of electrons during the accumulation of electrons with opposite spins on opposite surfaces of the metal film with strong spin-orbit coupling. [ABSTRACT FROM AUTHOR]

Spintronics and condensed matter physics are in pursuit of materials that can serve as carriers for novel quantum devices. Antiferromagnetic rare earth orthoferrites (R FeO 3 , where R is rare earth or Y), are potential functional materials for magnetic information processing. They exhibit temperature-controlled spin reorientation transition (SRT) and magnetic field/temperature-induced spin switching (SSW) properties. As such, R FeO 3 is expected to be used in spintronic devices that can easily control the spin. With the advancement of research, the co-doping of rare earth ions has emerged as a prominent area of investigation in R FeO 3. In this work, we have grown a series of Tm 1- x Sm x FeO 3 (TSFO, x = 0, 0.2, 0.3, 0.4) single crystals via a four-mirror optical floating zone furnace. Crystal axes and single phase of these single crystals were determined using Laue back reflection camera and X-ray diffractometer. We observed that the doping of Sm ions can effectively regulate the spin reorientation temperature of the parent material TmFeO 3. Both type-I and type-II SSW have been observed when the doping rate x is 0.2 or 0.4, perfectly integrating the magnetic properties of TmFeO 3 and SmFeO 3 single crystals. Furthermore, the spin switching in TSFO (x = 0.2, 0.3, 0.4) can be manipulated by applying low magnetic fields with tens of Oe. On the other hand, when the doping rate x reaches 0.4, the magnetic compensation phenomenon and the Néer temperature of rare earth ions occurred. The super-exchange interaction between R 3+ and Fe3+ magnetic sublattices leads to these interesting phenomena. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Chinese Society of Rare Earths is the property of Editorial Department of Journal of the Chinese Society of Rare Earths and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this research, the single-phase tetragon NdMn2-xAgxSi2 (0 ≤ x ≤ 0.4) alloys were prepared. It was found that the phase transition temperature was decreased by evaluating Ag substitution, which was attributed to the enhancement of orbital hybridization. The thermomagnetic hysteresis disappears for x ≥ 0.2. For Δμ0H of 0–7 T, the values of the maximum magnetic entropy change (the relative cooling power) are 22.2 J/kgK (420.7 J/kg), 20.1 J/kgK (500.5 J/kg), 19.9 J/kgK (552.8 J/kg) and 12.0 J/kgK (300.0 J/kg) in NdMn2-xAgxSi2 (x = 0, 0.2, 0.3 and 0.4) alloys. The XPS valence band spectra indicate that the density of electron and the hybridization effect is enhanced by increasing the substitution amount of Ag. This is attributed to the fact that the atomic radius of Ag is larger than that of Mn, resulting in the strengthening of the covalent bond between Ag and Si. [ABSTRACT FROM AUTHOR]

In this work, we investigated the influence of Co on the structure and magnetic properties of Ni50-xCoxMn29Ga21 (x = 0, 2, 4, 6, and 8) shape memory alloy ribbons fabricated by using the melt-spinning method. The addition of Co increases the formation of the austenitic crystalline phase in the alloy ribbons. The crystalline grains in rod-shapes with diameter of ~2 μm and length of ~10μm are mostly oriented perpendicular to the ribbon surface. The martensitic-austenitic transformation was performed on both the thermomagnetization and differential scanning calorimetry methods. With the increase of Co concentration, the martensitic-austenitic structural phase transformation temperature (TM-A) of the alloy gradually decreases while the Curie temperature of the austenite phase (TCA) of the alloy increases from 355K (for x = 0) to 432K (for x = 8). Besides, the martensitic-austenitic phase transformation is also significantly affected by the external magnetic field. The structural phase transformation temperature of the alloy tends to shift towards lower temperatures as the external magnetic field increases. [ABSTRACT FROM AUTHOR]

Perovskite oxide BaNi0.5Mn0.25Fe0.25O3 was successfully synthesized using a sol–gel method. Structural refinement analysis has been performed to investigate the details of the crystalline structure which was found to be a rhombohedral system at room temperature with the space group R 3 ¯ C . Crystallite size, lattice strain, density and porosity parameters were also calculated. The morphology and the elemental composition were analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Raman scattering spectroscopy has been performed in order to study the vibrational modes and the various bond formations of the synthesized sample. The study of the magnetic properties shows a ferro-paramagnetic transition (FM–PM) at the curie temperature. The electrical behavior of this double perovskite was also studied using complex impedance spectroscopy. Electrical conduction follows Jonscher's power law, and the conduction mechanisms are identified. The variations of the real and imaginary parts of impedance according to the frequency and temperature show the presence of a relaxation phenomenon in the sample, and it is thus a potential candidate for various technological applications in microelectronics and energy storage. [ABSTRACT FROM AUTHOR]

The La0.88Sr0.12MnO3 nanocrystalline is synthesized by sol-gel chemical method, shows a typical paramagnetic-ferromagnetic phase transition at 280 K. A thorough study on critical behavior analysis of magnetization isotherms is performed by various techniques such as modified Arrott plot, Kouvel-Fisher method, and critical isotherm analysis. Based on these methods, the accurate critical exponents (β = 0.5936(2) and γ = 1.0928(6)) are determined. Both critical exponents (β and γ) have been confirmed to fulfill the Widom scaling relation δ = 1+ γ β . Moreover, these exponents also obey the single scaling equation of H M δ = h ( ε H 1 / β ) . The obtained critical exponents are closer to the theoretical prediction of mean-field model but shows a slight deviation from theoretical values. We proposed that this deviation is due to the inherent disorder effect as the dimension of La0.88Sr0.12MnO3 particles reduced to nanoscale. Highlight: La0.88Sr0.12MnO3 nanocrystalline is prepared by the sol-gel method. The critical properties associated with the ferromagnetic transition are investigated by various techniques. The critical exponents show a slight deviation from theoretical values due to the inherent disorder effect when the La0.88Sr0.12MnO3 particles reduced to nanoscale. [ABSTRACT FROM AUTHOR]

MnSb2Te4 has a similar structure to an emerging material, MnBi2Te4. According to earlier theoretical studies, the formation energy of Mn antisite defects in MnSb2Te4 is negative, suggesting its inherent instability. This is clearly in contrast to the successful synthesis of experimental samples of MnSb2Te4. Here, the growth environment of MnSb2Te4 and the intrinsic defects are correspondingly investigated. We find that the Mn antisite defect is the most stable defect in the system, and a Mn-rich growth environment favors its formation. The thermodynamic equilibrium concentrations of the Mn antisite defects could be as high as 15% under Mn-poor conditions and 31% under Mn-rich conditions. It is also found that Mn antisite defects prefer a uniform distribution. In addition, the Mn antisite defects can modulate the interlayer magnetic coupling in MnSb2Te4, leading to a transition from the ideal antiferromagnetic ground state to a ferromagnetic state. The ferromagnetic coupling effect can be further enhanced by controlling the defect concentration. [ABSTRACT FROM AUTHOR]

Rare earth-based materials with a large magneto-caloric (MC) effect have aroused significant research interest due to their potential application for cryogenic magnetic refrigeration (MR) technology. In this study, the Cu site Zn-substituted Dy2BaCu1−xZnxO5 oxides were synthesized and systematically investigated concerning the structural, magnetic phase transition, and MC properties. All the Dy2BaCu1−xZnxO5 oxides were found to be single-phased with an orthorhombic crystal structure (space group Pnma). With the increase of Zn content in the Dy2BaCu1−xZnxO5 oxides, the magnetic phase transition (MPT) temperature decreases gradually from 12.1 K to 2.1 K and the nature of MPT changes from first-order to second-order type. Moreover, Zn substitution leads to enhanced MC performance. The maximum magnetic entropy changes, temperature-averaged entropy changes with 5 K-lift, and relative cooling powers under the magnetic field change of 0–70 kOe were evaluated to be 8.49 J/kgK, 9.67 J/kgK and 13.23 J/kgK, 8.38 J/kgK, 9.29 J/kgK, and 13.03 J/kgK and 227.43 J/kg, and 283.63 J/kg and 343.04 J/kg for Dy2BaCu0.75Zn0.25O5, Dy2BaCu0.5Zn0.5O5 , and Dy2BaCu0.25Zn0.75O5, respectively. The observed tunable MPT and enhanced MC performances indicate that the present Dy2BaCu1−xZnxO5 oxides have potential for practical cryogenic MR applications. [ABSTRACT FROM AUTHOR]

Control over magnetic properties by optical stimulation is not only interesting from the physics point of view, but also important for practical applications such as magneto-optical devices. Here, based on a simple tight-binding (TB) model, we propose a general theory of light-induced magnetic phase transition (MPT) in antiferromagnets. Considering the fact that the bandgap of the antiferromagnetic (AFM) phase is usually larger than that of the ferromagnetic (FM) one for a given system, we suggest that light-induced electronic excitation prefers to stabilize the FM state over the AFM one, and will induce an MPT from AFM phase to FM phase once a critical photocarrier concentration (αc) is reached. This theory has been confirmed by performing first-principles calculations on a series of 2D van der Waals (vdW) antiferromagnets. Interestingly, a linear relationship between αc and the intrinsic material parameters is obtained, in agreement with our TB model analysis. Our general theory paves a new way to manipulate 2D magnetism with high speed and superior resolution. [ABSTRACT FROM AUTHOR]

The characteristic size of the magnetocaloric materials in magnetic refrigerators, thermomagnetic regenerators and energy harvesters is usually down to micrometer and nanometer length scales, which provides the largest possible contact surface area to the heat transfer liquid. Therefore, it is pivotal to investigate the structural, magnetic and magnetocaloric properties of magnetocaloric materials at micrometer and nanometer length scales. In the present study, we have successfully fabricated MnCoGe-based thin films using the pulsed laser deposition (PLD) technique. The as-deposited film shows a dense surface, homogeneous chemical distribution and a preferred orientation along the c -axis of the hexagonal Ni 2 In-type structure. In-situ temperature-dependent X-ray diffraction measurements on the as-deposited films reveal an irreversible structural degradation above 300 °C due to the considerable evaporation of the Mn atoms, which causes the formation of microscale pores in the films. The thermomagnetic behavior of the film annealed at 250 °C displays a reversible second-order ferromagnetic transition of the hexagonal phase at Curie temperature T C = 275 K, and a first-order hexagonal-orthorhombic structural transition below 200 K. The decoupling of the magnetic and structural transitions brings reversible magnetocaloric effect with the entropy change ΔS values of 2.5 J/(kgK) and the refrigeration capacity reaching 89 J/kg in Δμ 0 H = 5 T, which are comparable to other reported magnetocaloric thin films. Moreover, antiferromagnetic coupling in the low-temperature orthorhombic phase was observed, which has rarely been reported in the MnCoGe-based bulk alloys. The different magnetic ground states between the thin film and the bulk alloys may be originated from the strain effect imposed by the Al 2 O 3 substrate. Consequently, this work not only provides insights into the structural, magnetic and magnetocaloric properties of the MnCoGe-based alloys at a nanometer length scale, but also offers a new idea for tailoring the multifunctional properties for this material family. [ABSTRACT FROM AUTHOR]

The crystal structure, magnetic properties, and magnetocaloric performances of Gd(Ga, x) (x = Al, Si) alloys have been systematically investigated. The single phase with a CrB-type orthorhombic structure (space group Cmcm) was observed for x ≤ 0.5 in GdGa1−xAlx and y ≤ 0.2 in GdGa1−ySiy alloys. All phase transitions of GdGa1−xAlx (0 ≤ x ≤ 0.5) alloys are of second-order and their Curie temperatures (TC) increase with the enhancement of the Al substitution amount. GdGa0.8Si0.2 alloy undergoes a first-order magnetic transition from antiferromagnetic (AFM) state to paramagnetic (PM) state. For Δμ0H of 0–7 T, the values of the maximum magnetic entropy change are 6.6 J/kg K, 7.7 J/kg K, 8.4 J/kg K, and 6.8 J/kg K in GdGa, GdGa0.7Al0.3, GdGa0.5Al0.5 , and GdGa0.8Si0.2 alloys, respectively. The magnetic entropy change is enhanced at the critical composition, which is ascribed to the lattice distortion. [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]

Magnetic materials exhibit various magnetic orders and are used in many magnetic and mechanical devices. In order to control and design magnetic ordering, the stability of the magnetic phase with mechanical strain has been reported in previous studies. In this study, based on the first-principles calculation, we investigate the stain dependence of the magnetic phase stability in iron with carrier doping. We find that the excess electron doping makes keeping the ferromagnetic (FM) phase for compressive strain loading in the (001) plane. On the other hand, hole doping leads to a multi-step strain-induced magnetic phase transition, and the spin spiral (SS) phase appears under the in-plane tensile strain. The 3d-orbital hybridization of up- and down-spin makes the hybridization gap, which is one origin of stabilized SS phase. FM phase under the in-plane strain and hole doping will be unstable due to the increasing 3d-orbital bands at Fermi energy; that is, SS phase will be the most stable state by the hybridization gap. The present study suggests that the excess electron/hole carrier doping and mechanical loading help to design a non-trivial magnetic phase in magnetic materials.

Magnetoelastic effect in R2Ni2In (R = Tb, Tm), associated with the antiferro- to paramagnetic phase transition at the Néel temperature TN equal to 40 K (R = Tb) or 4.8 K (R = Tm), has been investigated by neutron powder diffraction. Rietveld refinement reveals that the orthorhombic crystal structure, reported at room temperature, is stable down to low temperatures, including magnetically ordered state. Based on the diffraction data, thermal evolution of the lattice parameters a, b and c and the unit cell volume V have been determined. Both the lattice parameters as well as the unit cell volume show distinct jumps in the vicinity of the respective Néel temperatures, indicating presence of the magnetoelastic effect. The values of the lattice strains Δa, Δb, Δc and change of the unit cell volume ΔV, associated with the antiferro- to paramagnetic phase transition, are reported. [ABSTRACT FROM AUTHOR]

We present a simple approach (the mean spin method) to investigate the influence of the size of nanoparticles (thickness of ultrathin films) and the concentration of ≪ magnetic atoms ≫ on the critical temperature and magnetic susceptibility in the magnetic phase transition region. The critical spin-spin correlation indices for nanosized magnets are calculated using the scaling relation. It is shown that the critical concentration p C of the transition from an ordered to an unordered state increases as the characteristic size of nanoparticles (thickness of ultrathin films) decreases. The results obtained by the mean spin method are in qualitative agreement with the Monte Carlo simulation and experimental data. [ABSTRACT FROM AUTHOR]

Nanoscale magnetic patterning can lead to the formation of a variety of spin textures, depending on the intrinsic properties of the material and the microstructure. Here we report on the spin textures formed in laterally patterned antiferromagnetic (AF)/ferromagnetic (FM) thin film stripes with a period of 200 nm (100 nm FM/100 nm AF). We make use of the AF to FM phase transition in FeRh thin films at ∼100 °C, thereby creating a nanoscale pattern that is thermally switchable between AF/FM stripes and uniformly FM. A combination of spin-resolved photoemission electron microscopy, magnetic force microscopy, and magnetometry measurements allow direct nanoscale observations of the stray magnetic fields emergent from the nanopattern as well as the underlying magnetisation. Our measurements reveal pinning centres resistant to temperature cycling that govern the modulated spin-texture as well as a sub-texture consisting of grain-driven nanoscale magnetisation structure directed out of the film plane. The nanoscale magnetic structure is thus strongly influenced by the film microstructure. Signatures of exchange bias are not observed, most likely due to the small contact area between the AF and FM regions, combined with the fact that the interfaces between the damaged and undamaged regions are likely to be highly diffuse owing to the lateral scattering of incoming ions. These results show that temperature controllable spin textures can be created in FeRh thin films which could find application in domain wall, microwave, or magnonic devices. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigates the electronic structures, elastic behaviors, and magnetic properties of monolayer Ni 2 I 2 in two novel phases, P 3 ̄ m 1 and P 4 / n m m , using first-principles calculations and Monte Carlo simulations. The electronic structures of P 3 ̄ m 1 and P 4 / n m m phases show half-metallic properties with spin magnetic moments of 0.85 and 0.82 μ B respectively. Both phases exhibit mechanical and dynamic stability. The P 3 ̄ m 1 phase has isotropic elastic properties and good ductility, while the P 4 / n m m phase shows significant crystallographic anisotropy. The spin exchange coupling constants between the nearest and the next-nearest neighbor Ni ions in the P 4 / n m m phase are nearly an order of magnitude higher than those in the P 3 ̄ m 1 phase, with the former having a Curie temperature close to room temperature at 296 K, significantly higher than the 27 K of the latter. The strain modulation range for structural and magnetic phase transitions between the P 3 ̄ m 1 and P 4 / n m m phases is provided theoretically. • Ni 2 I 2 monolayer in two phases shows distinct spin polarization phenomena. • P 3 ̄ m 1 Ni 2 I 2 exhibits isotropic elasticity, while P4/nmm shows anisotropy. • P4/nmm phase shows a notably high Curie temperature of 296 K. • Theoretical prediction of strain-induced phase transitions in Ni 2 I 2 phases. [ABSTRACT FROM AUTHOR]

This report aims to investigate in depth FeMnO 3 , a material of interest due to its fascinating magnetic and multiferroic properties and its many applications in fields including lithium-ion batteries, microwave devices, and catalysis. However, understanding the precise stoichiometry of the material is crucial for a better comprehension of its physical properties. A cheap, simple, and repeatable sol-gel process was used to fabricate the FeMnO 3 nanocrystals. Comprehensive multi-technique characterization of the as-fabricated FeMnO 3 indicates that the main phase (94 wt%) is Fe 0.5 Mn 1.5 O 3 , although hematite appears as the minority phase (6 wt%). Magnetic characterization shows core-shell spin-glass like behavior, as well as paramagnetic-ferrimagnetic transitions and a Griffiths phase regime. EPR measurements revealed a strong and broad resonance line across the temperature range of 4.3 K–300 K, primarily influenced by the majority phase. The g-value decreases monotonically from 2.93 at 50 K to 2.18 at 300 K. There is a notable change in the resonance field and linewidth between 40 and 50 K, attributed to surface spin glass behavior. The EPR data below 50 K are in line with the core-shell model of (Fe 0.25 Mn 0.75) 2 O 3 nanoparticles. Below 50 K, the shell's spin system undergoes a transition from paramagnetic to spin-glass-like, with a critical temperature around 43 K. Above 50 K, the superparamagnetic minority phase significantly affects the temperature dependence of the resonance linewidth. These results hold particular importance as they advance our understanding of the intricate magnetic interactions present in FeMnO 3. For the best possible use of this material platform in new technologies, such insights are essential. [Display omitted] • Essentially, two distinct nanophases, namely the primary (Fe x Mn 1-x) 2 O 3 and secondary α -Fe 2 O 3 were successfully synthesized by the sol-gel method. • Through Mössbauer spectroscopy analysis and Rietveld refinement of X-ray diffraction data, the composition of the compound was well determined: a majority bixbyite phase (86 mol%, 94 wt%) with (Fe 0.25 Mn 0.75) 2 O 3 stoichiometry and average crystallite size of ∼48 nm, plus a minority hematite phase (14 mol%, i.e., 6 wt%) with an average crystallite size of ∼8 nm. • Regarding the Mössbauer spectrum at 80 K, the area ratio between the 24d and 8b crystallographic sites and the percentage areas of the two doublets were used as constraints in the Rietveld analysis of the x-ray diffraction (XRD) data. These combined techniques (Mössbauer + Rietveld refining) have been uses to precisely determine the stoichiometry for (Fe x Mn 1-x) 2 O 3 , i.e. x = 0.25. • Raman spectroscopy confirmed the presence of characteristic vibrational bands, supporting the identification of the majority phase. X-ray photoelectron spectroscopy analysis detected oxygen vacancies on the (Fe 0.25 Mn 0.75) 2 O 3 particle surface with varying oxidation states (Fe3+, Fe2+, Mn3+, and Mn4+). X-band magnetic resonance data exhibited a strong and broad resonance line throughout the temperature range (4.3 K ≤ T ≤ 300 K), primarily governed by the majority phase. • The temperature dependence of both resonance field and resonance linewidth shows a remarkable change in the range of 40–50 K, herein credited to surface spin glass behavior. The model picture used to explain the MR data in the lower temperature range (below about 50 K) assumes (Fe x Mn 1-x) 2 O 3 nanoparticles with a core-shell structure. These results indicate that below about 50 K the shell's spin system reveals a paramagnetic to spin glass-like transition upon cooling, with a critical temperature estimated at 43 ± 1 K. In the higher temperature range, the superparamagnetic hematite (secondary) phase contributes remarkably to the temperature dependence of the resonance linewidth. Zero-field-cooled (ZFC) and field-cooled (FC) data show strong irreversibility and a peak in the ZFC curve at ∼33 K, attributed to a paramagnetic-ferrimagnetic transition of the main phase. • Hysteresis curve at 5 K shows a low coercive field of 4 kOe, with the magnetization not reaching saturation at 70 kOe, suggesting the occurrence of a ferrimagnetic core with a magnetic disorder at surface, characteristic of core-shell spin-glass-like behavior. [ABSTRACT FROM AUTHOR]

We report experimental studies on a series of Rb(Co 1 − x Ni x) 2 Se 2 (0.02 ≤ x ≤ 0.9) powder and single crystal samples using x-ray diffraction, neutron diffraction, magnetic susceptibility, and electronic transport measurements. All compositions are metallic and adopt the body-centered tetragonal structure with I 4 / m m m space group. Anisotropic magnetic susceptibilities measured on single crystal samples suggest that Rb(Co 1 − x Ni x) 2 Se 2 undergo an evolution from ferromagnetism to antiferromagnetism, and finally to paramagnetism with increasing Ni concentration. Neutron diffraction measurements on the samples with x = 0.1, 0.4, and 0.6 reveal an A -type antiferromagnetic order with moments lying in the a b plane. The moment size changes from 0.69 (x = 0. 1) to 2.80 μ B (x = 0. 6) per Co ions. Our results demonstrate that dilution of the magnetic Co ions by substitution of nonmagnetic Ni ions induces magnetic localization and evolution from itinerant to localized magnetism in Rb(Co 1 − x Ni x) 2 Se 2. • Dilution of Co ions in Rb(Co 1 − x Ni x) 2 Se 2 enhances the moment size of the Co ions. • Replacing Co with Ni tunes the ground state progressively. • The superconductivity in RbNi 2 Se 2 is suppressed by 10% Co-doping. • Rb(Co 1 − x Ni x) 2 Se 2 is a suitable platform to investigate two-dimensional magnetism.. [ABSTRACT FROM AUTHOR]