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Cobalt doping's influence on the structural, magnetic, and electronic properties of the double spinel LiFeCr 4 O 8 was systematically investigated. Rietveld refinement revealed a consistent increase in lattice parameter a and unit cell volume with cobalt incorporation. Magnetic susceptibility measurements indicated three distinct transitions: an increase in the ferrimagnetic transition temperature (T N), a decrease in the magnetostructural transition temperature (T MS), and an increase in the spin gap transition by cobalt doping. Through diffuse reflectance spectroscopy the direct optical band gap (E og) was obtained with values of 1.169 eV, 1.303 eV, 1.396 eV, and 1.230 eV for x = 0.0, 0.1, 0.2, and 0.5, respectively. The observed increase in E og with cobalt doping suggests a widening of the band gap, which could be beneficial for optoelectronic applications. By means of X-ray photoelectron spectroscopy (XPS) the core levels of Li 1s , Co 3p , Fe 3p , Cr 3p , Fe 2p , Cr 2p , and O 1s were identified. XPS valence band (VB) analysis revealed a decreasing intensity at binding energy BE = 0 eV with respect to x = 0.0. Density functional theory calculations with Hubbard U correction (DFT + U) confirmed a ferrimagnetic semiconductor behavior with a direct electronic band gap (E eg) of 1.085 eV. [ABSTRACT FROM AUTHOR]

Orbital currents play a fundamental role in a wide range of transport phenomena. Recently, the discovery of a novel chiral orbital current state in the ferrimagnetic nodal-line semiconductor Mn3Si2Te6 has attracted significant interest, supported by anomalous I–V characteristics and time-dependent bistable switching. However, the direct experimental verifications, combining electrical transport and magnetic measurement, that detect the variation of the magnetic properties vs the current are still rare. Here, we investigate the transport properties of Mn3Si2Te6 and track the current-induced dynamics of the magnetic moment. Reflective magnetic circular dichroism reveals that significant alterations in Mn3Si2Te6 magnetoresistance in response to an electric field are necessarily coupled with a magnetic phase transition, establishing a rare correlation. Our findings indicate the predominance of magnetic chiral orbital currents in the colossal angular magnetoresistance effect, offering a unique platform for advanced studies in orbital magnetism. [ABSTRACT FROM AUTHOR]

Orbital currents play a fundamental role in a wide range of transport phenomena. Recently, the discovery of a novel chiral orbital current state in the ferrimagnetic nodal-line semiconductor Mn3Si2Te6 has attracted significant interest, supported by anomalous I–V characteristics and time-dependent bistable switching. However, the direct experimental verifications, combining electrical transport and magnetic measurement, that detect the variation of the magnetic properties vs the current are still rare. Here, we investigate the transport properties of Mn3Si2Te6 and track the current-induced dynamics of the magnetic moment. Reflective magnetic circular dichroism reveals that significant alterations in Mn3Si2Te6 magnetoresistance in response to an electric field are necessarily coupled with a magnetic phase transition, establishing a rare correlation. Our findings indicate the predominance of magnetic chiral orbital currents in the colossal angular magnetoresistance effect, offering a unique platform for advanced studies in orbital magnetism. [ABSTRACT FROM AUTHOR]

We have investigated, for the first time, the hyperthermia properties, antibacterial, anticancer and antioxidant activities, as well as their toxicity, of Mn 0.25 Mg 0.25 Co 0.5 Fe 2 O 4 nanoparticles synthesized by the sol-gel auto-combustion method. X-ray diffraction results revealed a pure phase and good crystallinity of the synthesized. In addition, the Fourier transform infrared (FTIR) spectrum confirmed the formation of the crystallographic sites of the synthesized structure. In terms of morphology, scanning electron microscopy (SEM) showed that the nanoparticles were agglomerated. In addition, transmission electron microscopy (TEM) revealed that the nanoparticles had a cubic shape and a nanometric size of around 32 nm. Energy-dispersive X-ray spectroscopy (EDS) confirmed the chemical composition of the nanoparticles. With regard to magnetic properties, magnetic measurements showed almost ferrimagnetic behavior, with a saturation magnetization of 38.90 emu/g at room temperature. Hyperthermia measurements revealed relatively good heating efficiencies, with SAR value of 33W/g, good temperature rise and short time to reach magnetic hyperthermia temperature 42 °C (8 min). For biological activities the nanoparticles showed an excellent capacity to neutralize free radicals, eliminating 97% of DPPH and 95% of hydrogen peroxide. The dose of 40 mg/kg of the nanoparticles caused significant alterations in hematological and biochemical profiles. The material showed a significant effect on various bacterial strains, including Staphylococcus aureus and Bacillus subtilis. The synthesized nanoparticles also showed significant activity against various cell lines, including MCF-7 and HeLa. These results strongly suggest the promising utilization of Mn 0.25 Mg 0.25 Co 0.5 Fe 2 O 4 , in many applications as a potential candidate for magnetic-mediated hyperthermia. [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]

Fe1.1Mn1.9O4 nanoparticles were successfully synthesized using a combustion method. The influence of the heating temperature on the evolution of the structural and magnetic properties has been studied using various methods. The structural analysis results revealed that as-synthesized nanoparticles have a tetragonal structure with an average size of ~24 nm. The magnetic measurements of the sample showed its ferrimagnetic nature at room temperature with hysteresis at low fields. Temperature-dependent magnetization measurements allowed for the conclusion that the Curie temperature for Fe1.1Mn1.9O4 nanoparticles was ~465 °C. After high-temperature magnetic measurements, during which the samples were heated to various maximum heating temperatures (Tmax.heat.) in the range from 500 to 900 °C, it was found that the structure of the samples after cooling to room temperature depended on the heating temperature. Herewith, when the heating temperature was 600 < Tmax.heat. < 700 °C, an irreversible structural phase transition occurred, and the cooled samples retained a high-temperature cubic structure. The results of the magnetic analysis showed that the samples, following high-temperature magnetic measurements, demonstrated ferrimagnetic behavior. [ABSTRACT FROM AUTHOR]

Perovskite-type ABO3 oxides show a number of cation-ordered structures, which have significant effects on their properties. The rock-salt-type order is dominant for B cations, and the layered order for A cations. In this work, we prepared a new perovskite-type oxide, Sm2CuMn(MnTi3)O12, with a rare columnar A-site order using a high-pressure, high-temperature method at about 6 GPa and about 1700 K. Its crystal structure was studied with synchrotron powder X-ray diffraction. The compound crystallizes in space group P42/nmc (No. 137) at room temperature with a = 7.53477 Å and c = 7.69788 Å. The magnetic properties of the compound were studied with dc and ac magnetic susceptibility measurements and specific heat. Spin-glass (SG) magnetic properties were found with TSG = 7 K, while specific heat, in the form of Cp/T, showed a strong, very broad anomaly developing below 20 K and peaking at 4 K. The dielectric constant of Sm2CuMn(MnTi3)O12 was nearly frequency and temperature independent between 8 K and 200 K, with a value of about 50. Cu2+ doping drastically modified the magnetic and dielectric properties of Sm2CuMn(MnTi3)O12 in comparison with the parent compound Sm2MnMn(MnTi3)O12, which showed a long-range ferrimagnetic order at 34–40 K. The antisite disorder of Cu2+ and Mn2+ cations between square-planar and octahedral sites was responsible for the SG magnetic properties of Sm2CuMn(MnTi3)O12. [ABSTRACT FROM AUTHOR]

Samples with inversion parameter values (δ) ranging from 0.27 to 0.14 while maintaining the crystallite size value have been successfully fabricated from commercially available powders by mechanical grinding and thermal annealing treatments at temperatures ranging between 400 and 600 °C. Detailed characterization studies of these samples using X-ray, neutron diffraction and magnetic measurements have confirmed for the first time the simultaneous coexistence at 2 K of short range antiferromagnetic and ferrimagnetic ordering for a wide range of the inversion parameter. The magnetic phase diagram obtained is different from the one previously reported, which shows at 2 K the coexistence of long range antiferromagnetic order and short range order for values of inversion parameters less than 0.1 and the presence of a ferrimagnetic order only for values of δ > 0.2. At room temperature, the Rietveld analysis of NPD patterns and the magnetization curves showed a paramagnetic behavior in the samples with δ ≤ 0.1. For the samples with higher cationic inversion, typical hysteresis curves of ferrimagnetic materials were observed and the saturation magnetization values obtained agree quite well with the net magnetic moment obtained from the Rietveld refinement of the neutron diffraction patterns. [ABSTRACT FROM AUTHOR]

The electromagnetic (EM) properties of shielded gyromagnetic spheres are characterized with the aid of an electrodynamic model formulated for the transverse electric (TE) modes of an isotropic sphere, in a similar way as dielectric resonators are commonly analyzed. Broadband characteristics of geometric and energy filling factors are presented. A new measure of the magnetic loss tangent is introduced which is positive despite the intrinsic permeability of the gyromagnetic medium being negative, where existing definitions yield a non-physical negative value. The sample size dependence of those quantities is also assessed. The conclusions from the analysis are applied to investigate and de-embed ferromagnetic linewidth errors which can occur in broadband measurements of magnetic garnet spheres. Magnetic anisotropy fields and the gyromagnetic $g$ -factor are also estimated from the measurement data. Experiments were performed in a two-port subwavelength cavity, covering a frequency range of up to 28 GHz. Additionally, two-port rectangular resonant cavity linewidth measurements at a few modes have been conducted. Good agreement between the two methods is found if the systematic error is accounted for. [ABSTRACT FROM AUTHOR]

Coated Ni0.5Co0.5Fe(2−x–y)GdxEryO4 (x = 0.3, y = 0.1) nanoparticles were synthesized by the co-precipitation method for the first time. The obtained nanoparticles were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and Magnetic Property Measurement System (MPMS). The analysis of XDR confirms the formation of single-phase spinel with an average crystallinity size value of 18 nm. FTIR showed the formation of octahedral and tetrahedral sites and the formation of bonds between the nanoparticles and oleic acid. TEM showed the formation of quasi-spherical nanoparticles. TGA showed that oleic acid is adsorbed at the surface of the nanoparticles. The analysis of magnetic properties showed a weak ferrimagnetic behavior at 300 K and a hard ferrimagnetic behavior at 80 K and 5 K with a blocking temperature value higher than that of the ambient temperature. [ABSTRACT FROM AUTHOR]

We report the structural and magnetic behavior of single phase inverse Heusler alloys Cr2Co(1−x)CrxAl (x = 0, 0.2, and 0.4) by using x-ray diffraction (XRD), Raman spectroscopy, isothermal magnetization, and magnetic susceptibility measurements. Interestingly, the Rietveld refinement of XRD data with space group I 4 ¯ m 2 reveal a tetragonal distortion with a c/a ratio around 1.38 in these inverse Heusler structures. The bulk compositions have been confirmed by energy dispersive x-ray spectroscopy measurements. The active Raman mode F2g is observed at 320 cm−1, which confirms the X-type Heusler structure, as the A2 and B2 type structures are known to be not Raman active. The area of F2g mode decreases with an increase in the Cr concentration, which indicates that the origin of this mode is due to Co vibrations. The isothermal magnetization data confirm the magnetic moment to be close to zero (≤0.02 μB/f.u.) at ≈70 kOe and the negligible coercive field suggests the fully compensated ferrimagnetic nature of these samples. The susceptibility behavior indicates irreversibility between zero-field and field-cooled curves and complex magnetic interactions at low temperatures. [ABSTRACT FROM AUTHOR]

The crystal structure of the first-synthesized compound EuErCuS 3 was determined from X-ray powder diffraction data: orthorhombic crystal system, space group Pnma , structural type Eu 2 CuS 3 : a = 10.1005(2) Å, b = 3.91255(4)Å, c = 12.8480(2) Å; V = 507.737(14) Å3, Z = 4, and ρ x = 6.266 g/cm3. The temperatures and enthalpies of reversible polymorphic transitions and incongruent melting of the compound were determined by DSC: T α↔β = 1524 K, ΔН α↔β = 2.3 ± 0.2 kJ∙mol−1; T β↔γ = 1575 K, ΔН β↔γ = 0.7 ± 0.1 kJ∙mol−1; T γ↔δ = 1602 K; ΔН γ↔δ = 1.3 ± 0.1 kJ∙mol−1 and T cr = 1735 ± 10 K, ΔН cr = −3.5 ± 0.3 kJ∙mol−1. IR spectra were recorded in the range from 50 to 400 cm−1. The compound was found to be IR-transparent in the range 4000–400 cm−1. The compound was characterized by Raman spectroscopy. The observed spectra featured both Raman lines and luminescence. Ab initio calculations of the EuErCuS 3 crystal structure and phonon spectrum were performed, the frequencies and types of fundamental modes were determined, and the involvement of constituent ions in the IR and Raman modes was assessed from an analysis of the ab initio displacement vectors. The vibrational spectra were interpreted. EuErCuS 3 manifests a ferrimagnetic transition at 4.8 K. Its microhardness is 2850 MPa. The obtained data can serve as the basis for predicting the properties of EuLnCuS 3 compounds. Valence states for Eu (2+) and Er (3+) are proved both by the XRD and optical methods. Optical band gap was found to be 1.934 eV from diffuse reflectance spectrum. Image 1 • The EuLnCuS 3 compound exhibit ferrimagnetic properties at low temperature. • The polymorphic transitions for EuLnCuS 3 are identified at high temperature. • EuErCuS 3 is a wide-gap semiconductor. • Valence purity of Eu2+ is proved via both XRD and optical techniques • The ab initio calculation of the Raman and infrared spectra of EuErCuS 3 , made for Pnma symmetry, agrees well with experiment. [ABSTRACT FROM AUTHOR]

Di-phase ferroelectric-ferrite composites with the same composition close to the percolation limit (0.66BaTiO 3 -0.33CoFe 2 O 4) and with different phase arrangements (randomly mixed phases and tri-layer structures) have been consolidated by using spark plasma sintering and their properties were comparatively analyzed. The intrinsic effective dielectric constant has been estimated by using finite element method and a value almost ten times higher was predicted for the randomly mixed composite, as result of different field distributions inside the ferrite and ferroelectric phases. At room temperature, experimental permittivity contains an intrinsic behavior overlapped onto a very strong extrinsic component determined by the interfaces and by local charge inhomogeneity. The extrinsic dielectric behavior has been discussed in terms of thermally activated relaxation mechanisms developed in both types of investigated structures, as revealed by the temperature-dependence impedance spectroscopy. The magnetic properties are derived as "sum property" from the ferrimagnetic character of CoFe 2 O 4 and show the lowest magnetization for the randomly mixed composites and a weak magnetic anisotropy when the magnetic field was applied in-plane or out-of-plane in the layered structure. Due to the different levels of interface doping specific to the different types of interfaces, the magnetic Curie temperature of the two composites ranges from 720 K in the randomly mixed structure to 746 K for the layered one. The ferroelectric P (E) loops and a modest ME coefficient of 14 mVOe−1cm−1 at 100 Hz were determined only for the layered structure, due to the high leakage and to the small grain size (below 200 nm) in the ferroelectric BaTiO 3 component. • Randomly mixed and tri-layered structure composites were comparatively investigated. • Role of the phase arrangement on the dielectric properties was predicted by FEM. • Experimental dielectric data contains a strong influence from extrinsic phenomena. • Magnetic properties slightly depend on the phase arrangement. [ABSTRACT FROM AUTHOR]

Here, we report structural and magnetic phase transitions in NiCr 1.9 Fe 0.1 O 4 nanoparticles of size ∼60 nm synthesized through cost-effective co-precipitation route. X-ray diffraction pattern shows a stable cubic phase at RT in contrast to tetragonal phase in bulk NiCr 2 O 4. Decreasing the temperature, a complete tetragonal symmetry is observed at 50 K, while a coexistence of cubic and tetragonal phases in the intermediate temperature range. Interestingly, no tetragonal to orthorhombic phase transformation has been observed down to 12 K as observed in NiCr 2 O 4 at 70 K. The local structure examined from temperature dependent EXAFS demonstrates that although no change in distribution of cations among tetrahedral (A) and octahedral (B) sites down to 10 K has been observed, Fe3+ ions occupy A site replacing equivalent amount of Ni2+ towards B site which is contradicting to the bulk NiCr 2 O 4 where Ni2+ occupies only A site. Magnetic studies demonstrate a two-fold increase in para to long-range ferrimagnetic transition, T C , due to increase in A-B exchange interaction and no change in spiral ordering temperature, T S indicates strong B-B interaction. In addition, these nanoparticles exhibit unusually high spontaneous exchange bias of ∼1.265 kOe at 60 K. We discuss the temperature dependent exchange bias on the basis of competition between uncompensated B site moments and ferromagnetically ordered spins at A site. The tunable exchange bias without field highlight the potential applications of these materials in spintronics devices. [ABSTRACT FROM AUTHOR]

This work is focusing on electrospinning polyethylene oxide (PEO) with incorporated barium ferrite nano-particles (BaFe) and the characterization of the magnetic properties of the obtained composites fibers. The barium ferrite powders used belong to a group of ferrites with hexagonal crystal structure. PEO has low toxicity, is water soluble, and is available in a variety of molecular weights of which 600.000 g/mol was used in this study. Following successful electrospinning of magnetic composite fibers, we have selected two samples, denoted as S1 and S2, for further investigation. The process parameters corresponding to the production of S1 and S2 differ only by the needle tip-to-collector distance which is larger for S2 (70 mm as compared to 50 mm). SEM images and fiber diameter distributions reveal that, as previously shown for pure PEO electrospun fibers, the average fiber diameter is decreasing with decreasing tip-collector distance. In addition, the distribution of the fiber diameters for the S1 sample is wider than the one for S2. This is indicative of a less controlled electrospinning process in the case of the S1 sample. Magnetic measurements on composite fibers reveal an expected ferrimagnetic behavior and no major differences between the magnetic properties of S1 and S2. [ABSTRACT FROM AUTHOR]

Abstract Exchange bias behaviors up to room temperature have been observed in NiCo 2 O 4 /NiO nanoparticle system. The field-cooled magnetic hysteresis loops exhibit shifts both in the field and magnetization axes simultaneously. The variation of exchange bias field and magnetization shift depends strongly on the measuring temperature. In addition, the dependence of exchange bias effect on measuring temperature is not monotonous, which is reflected in the different tendency during the decrease process of magnetization shift and exchange bias field. The exchange bias field is decreased firstly at the range of 10–50 K followed by an increase of 50–200 K and decreased again of 200–320 K. By analyzing various magnetic measurements, the special exchange bias effect in NiCo 2 O 4 /NiO can be owing to the spin glass state and the ferrimagnetic/antiferromagnetic coupling during different temperature ranges. [ABSTRACT FROM AUTHOR]

Exfoliated graphite (EG) is a promising sorbent for oil and organic pollutants, which has a high sorption capacity and hydrophobicity. Modifying the EG with ferrimagnetic compound allows EG with sorbed oil to be collected from the water surface with the use of a magnetic field. The aim of this work is to obtain a sorbent based on exfoliated graphite with ferrimagnetic maghemite (γ-Fe 2 O 3) and investigate its structure and functional properties. The preparation of iron-containing EG includes the impregnation of expandable graphite with a FeCl 3 water solution and the thermal treatment of impregnated expandable graphite at temperatures between 400 and 1000 °C. Mossbauer spectroscopy, X-ray diffraction analysis, scanning electron microscopy and energy dispersive X-ray spectroscopy show the evolution of the iron-containing phase from FeOCl to the mixture of α-Fe 2 O 3 and γ-Fe 2 O 3 , which grants magnetic properties to the samples. EG obtained at 1000 °C has a saturation magnetization of 22.7 emu g−1. High macropore and meso-/micropore volume investigated by mercury porosimetry and nitrogen adsorption-desorption method results in a high sorption rate and sorption capacity of EG up to 30 g g−1 toward oil and liquid hydrocarbons. At the same time, the EG sorption capacity toward water is ten times lower. [Display omitted] • Exfoliated graphite/γ-Fe 2 O 3 is obtained from expandable graphite/FeCl 3. • Evolution of the iron-containing phase was investigated by Mossbauer spectroscopy. • Consequent formation of FeOCl, α-Fe 2 O 3 and γ-Fe 2 O 3 is observed. • γ-Fe 2 O 3 content increases when increasing the thermal treatment temperature. • EG/γ-Fe 2 O 3 has high saturation magnetization and oil sorption capacity. [ABSTRACT FROM AUTHOR]

Polycrystalline sample of Bi 2 Cu 5 B 4 O 14 was synthesized and its structural and magnetic properties were investigated by means of temperature dependent x-ray diffraction, magnetization, and heat capacity measurements. Bi 2 Cu 5 B 4 O 14 is found to be a spin-1/2 layered compound with repeating Cu-pentamer units. DC magnetic susceptibility at high temperatures follows the Curie-Weiss law with a large and negative Curie-Weiss temperature θ CW ≃ −39 K, suggesting the dominant ferromagnetic interaction between Cu 2+ ions. A positive curvature in inverse susceptibility and a magnetization hysteresis with reduced ordered moment at T = 2.1 K pinpoint the ferrimagnetic nature of the compound with T C ≃ 25 K. The modified Arrott analysis shows that Bi 2 Cu 5 B 4 O 14 is a good example of Heisenberg ( β = 0.367 and γ = 1.388) ferrimagnet. Heat capacity data at low temperatures (i.e. in the ordered state) follows a power law ( γT α ) with a reduced exponent ( α ≃ 2.58). The change in magnetic entropy is calculated to be S mag ≃ 28 J/mol K at around 100 K which is close to the expected theoretical value of 28.81 J/mol K for Bi 2 Cu 5 B 4 O 14 . [ABSTRACT FROM AUTHOR]

This paper describes the preparation and obtained magnetic properties of large single domain iron oxide nanoparticles. Such ferrimagnetic particles are particularly interesting for diagnostic and therapeutic applications in medicine or (bio)technology. The particles were prepared by a modified oxidation method of non-magnetic precursors following the green rust synthesis and characterized regarding their structural and magnetic properties. For increasing preparation temperatures (5 to 85 °C), an increasing particle size in the range of 30 to 60 nm is observed. Magnetic measurements confirm a single domain ferrimagnetic behavior with a mean saturation magnetization of ca. 90 Am2/kg and a size-dependent coercivity in the range of 6 to 15 kA/m. The samples show a specific absorption rate (SAR) of up to 600 W/g, which is promising for magnetic hyperthermia application. For particle preparation temperatures above 45 °C, a non-magnetic impurity phase occurs besides the magnetic iron oxides that results in a reduced net saturation magnetization. [ABSTRACT FROM AUTHOR]

• Mn Zn ferrite particles with a size of ≈ 12 nm are prepared by hydrothermal synthesis. • Analysis by Mössbauer spectroscopy and neutron diffraction reveals a metastable state. • Mn 0.6 Zn 0.4 Fe 2 O 4 particles show a non-equilibrium distribution of Zn and Mn. • Superparamagnetism is studied on time scales of Mössbauer and magnetic measurements. • Transition to superparamagnetic state is easily controlled by Zn content. Magnetic behaviour of nanoparticles deviates from their bulk equivalents not only due to finite-size and surface effects but it may be also affected by occurrence of metastable states, such as non-equilibrium cation distribution. The chemical composition along with the specific cation distribution are decisive for magnetic properties of spinel ferrites, the nanoparticles of which can be easily tailored to exhibit peculiar properties suitable for various applications. The present study is devoted to hydrothermally prepared Mn Zn ferrite nanoparticles; namely to five samples with approximate composition Mn 1− x Zn x Fe 2 O 4 , where x = 0.21–0.63, that were prepared by a surfactant-free hydrothermal procedure at a rather low temperature of 180 °C. XRD measurements evidenced the cubic spinel structure and a gradual decrease of the mean crystallite size from 14 to 10 nm with increasing zinc content, which was further confirmed by TEM analysis. 57Fe Mössbauer spectroscopy and temperature-variable magnetic measurements provided valuable insight into the blocking behaviour of particles on two dramatically different time scales and demonstrated that Néel relaxation can be enhanced by increasing the zinc content. Nanoparticles of the selected composition Mn 0.62 Zn 0.41 Fe 1.97 O 4 were subjected to neutron diffraction study at 2 K to determine the ferrimagnetic order and in combination with Mössbauer spectroscopy to analyse the cation distribution. The non-zero occupancy of Zn2+ in octahedral sites evidenced a metastable distribution, and the supplemental DFT study revealed that the distribution of Mn2+ is non-equilibrium as well. [ABSTRACT FROM AUTHOR]

The GdTi 0.05 Fe 0.95- x Mn x Si, х = 0–0.95 intermetallic compounds with a tetragonal crystal structure of the CeFeSi type (space group P4/nmm, N 129, tP6) have been studied. The lattice parameter c and the Curie temperature T C increase quickly, whereas the lattice parameter a is almost unchanged in the system when the content of Mn increases. The saturation magnetization, magnetocaloric effect MCE and refrigerant capacity RC change non-monotonically with a dip at intermediate compositions that is presumably due to the canted ferrimagnetic structure of these compounds. The MCE and RC vary in a field changing to 17 kOe within the small ranges of 1.6–2.7 J/kgK and 60–117 J/kg around T C , respectively, while T C changes in a wide range around the room temperature from 160 to 360 K. • The lattice parameter c and T C increase and lattice parameter a is almost unchanged. • Presumably, the canted ferrimagnetic structure is formed in the system. • М sat. , MCE, RC change non-monotonically with a dip at intermediate compositions. • MCE, RC , T C vary in the ranges 1.6–2.7 J/kgK, 60–117 J/kg at 17 kOe field, 160–360 K. [ABSTRACT FROM AUTHOR]

During the past few decades, hybrid nanoparticles (HNPs) based on a magnetic material and gold have attracted interest for applications in catalysis, diagnostics and nanomedicine. In this paper, magnetic CoFe2O4/Au HNPs with an average particle size of 20 nm, decorated with 2 nm gold clusters, were prepared using methionine as a reducer and an anchor between CoFe2O4 and gold. The methionine was used to grow the Au clusters to a solid gold shell (up to 10 gold deposition cycles). The obtained nanoparticles (NPs) were studied by X-Ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-Ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy techniques. The TEM images of the obtained HNPs showed that the surface of cobalt ferrite was covered with gold nanoclusters, the size of which slightly increased with an increase in the number of gold deposition cycles (from 2.12 ± 0.15 nm after 1 cycle to 2.46 ± 0.13 nm after 10 cycles). The density of the Au clusters on the cobalt ferrite surface insignificantly decreased during repeated stages of gold deposition: 21.4 ± 2.7 Au NPs/CoFe2O4 NP after 1 cycle, 19.0 ± 1.2 after 6 cycles and 18.0 ± 1.4 after 10 cycles. The magnetic measurements showed that the obtained HNPs possessed typical ferrimagnetic behavior, which corresponds to that of CoFe2O4 nanoparticles. The toxicity evaluation of the synthesized HNPs on Chlorella vulgaris indicated that they can be applied to biomedical applications such as magnetic hyperthermia, photothermal therapy, drug delivery, bioimaging and biosensing. [ABSTRACT FROM AUTHOR]

The synthesis, structural characterization, and magnetic properties of La 3 Mn 2 NbO 9 double perovskite are reported. The crystal structure has been refined by X-ray and neutron powder diffraction data in the monoclinic space group P2 1 /n. The Mn2+, Mn3+ and Nb5+ cations are distributed at the 2d and 2c Wyckoff sites, with a high cation order degree in the latter, mainly occupied by Mn2+/Mn3+. The Mn3+ presence was established from X-ray Emission Spectroscopy and X-ray Photoelectron Spectroscopy. Rietveld refinements of powder neutron diffraction data show that at room temperature the cell parameters are a= 5.6063(3) Å, b= 5.8155(3) Å, c= 7.9877(2) Å y β= 89.89(1)°. Magnetization measurements indicate the presence of ferromagnetic and antiferromagnetic interactions with T C ∼19 K and T N ∼11 K, respectively, with a magnetic cell of symmetry Γ 1 (A g). The analysis of the neutron data suggests a canted ferrimagnetic spin structure where an antiferromagnetic unit-cell in a and c axis, and ferromagnetic in b axis with a propagation vector k = (0 ½ 0) was used. The effective magnetic moment obtained experimentally is μ eff = 5.50 μ B /mol Mn2+/3+, slightly lower than the theoretical one for spin only (5.83 μ B). • Synthesis of new double perovskite La 3 Mn 2 NbO 9. • Canted ferrimagnetism due to the high degree of structural distortion. • Effective existence of Mn2+/Mn3+ mixture. • Multiple possible magnetic interactions and huge distortion of the octahedral network allow AFM and FM couplings. [ABSTRACT FROM AUTHOR]

The structure and magnetic properties of the mixed technetium-ruthenium perovskites SrTc x Ru 1-x O 3 (x ​= ​0.25 and 0.5) have been investigated using variable temperature synchrotron X-ray diffraction, magnetic susceptibility measurements, and DFT calculations. Both oxides are isostructural with SrRuO 3 and SrTcO 3 , and there is no evidence of long-range cation order. Magnetostriction is observed along the c -axis for both oxides. The inverse susceptibility and DFT calculations suggest a cation-disordered ferrimagnetic ground state for SrTc0.5Ru0.5O3. Image 1 • Mixed technetium-ruthenium perovskites SrTc x Ru 1-x O 3 oxides prepared. • Structures determined using temperature synchrotron X-ray diffraction. • Magnetic susceptibility measurements suggest a ferrimagnetic ground state. • DFT calculations suggest a cation-disordered ferrimagnetic ground. [ABSTRACT FROM AUTHOR]

Search for low-moment magnetic materials with high spin-polarization is important for emerging spintronics applications. In this work, we have conducted detailed growth and characterization along with complementary first-principles calculations to investigate the structure and magnetism of Mn 2 FeSi, which is a prospective inverse-Heusler material. We confirm that Mn 2 FeSi adopts a cubic inverse-Heusler structure, in excellent agreement with theory. The magnetic and resistivity measurements show an antiferromagnetic behavior with a Néel temperature of 48 K, which is consistent with prior experimental reports. We find that a low-moment state with higher ordering temperature (150–200 K) can be stabilized under certain growth conditions. Supporting calculations show that Neel-type antiferromagnetic states are energetically very close to the ferrimagnetic ground state. Our work provides evidence that Mn 2 FeSi may be interesting for exploring newer applications with low-moment materials, but the ordering temperatures are low for viable practical applications. • The experimental work reported here confirms a theory prediction into the structure of a relatively unexplored magnetic Heusler material (Mn 2 FeSi). • Such materials can be promising to explore the emerging area of antiferromagnetic spintronics. [ABSTRACT FROM AUTHOR]