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The core and surface structure, and magnetism of mechano-synthesized LaFeO3 nanoparticles (30–40 nm), Eu3+-doped (La0.70Eu0.30FeO3), and Eu3+/Cr3+ co-doped (La0.70Eu0.30Fe0.95Cr0.05O3) are reported. Doping results in a transition from the O′-type to the O-type distorted structure. Traces of reactants, intermediate phases, and a small amount of Eu2+ ions were detected on the surfaces of the nanoparticles. The nanoparticles consist of antiferromagnetic cores flanked by ferromagnetic shells. The Eu3+ dopant ions enhance the magnetization values relative to those of the pristine nanoparticles and result in magnetic susceptibilities compatible with the presence of Eu3+ van Vleck paramagnetism of spin–orbit coupling constant (λ = 363 cm−1) and a low temperature Curie–Weiss like behavior associated with the minority Eu2+ ions. Anomalous temperature-dependent magnetic hardening due to competing magnetic anisotropy and magnetoelectric coupling effects together with a temperature-dependent dopant-sensitive exchange bias, caused by thermally activated spin reversals at the core of the nanoparticles, were observed. [ABSTRACT FROM AUTHOR]

LaFeO3 perovskite oxide were synthesized through solution combustion technique using ascorbic acid as phytochemical fuel. The sample was characterized using techniques such as XRD, FTIR, UV-Visible spectroscopy, SEM with EDX and XPS. The magnetic hysteresis behavior was studied using VSM measurement at room temperature. The orthorhombic primitive lattices of LaFeO3 under the space group Pnma was confirmed from XRD pattern and the lattice parameters were obtained using Rietveld profile refinement. The crystallographic structure and lattice parameters were found consistent with the data presented in the ICDD PCPDFWIN Number 37-1493 file. Using Scherrer equation the average crystallite size (26 nm) was estimated. The strain separated effective crystallite size (35 nm) was estimated using the model suggested by Williamson–Hall. The M–O bond vibration bands correspond to LaFeO3 crystal lattice were elucidated from FTIR spectrum. Using the raw reflectance data from UV-Visible spectrum, Tauc' plot analysis employing Kubelka Munk function was performed; from which the optical direct band gap (2.41 eV) was estimated. The particle size distribution and elemental composition were estimated from SEM with EDX. The binding energies obtained from deconvoluted XPS spectra accurately provide the valence state electronic configuration corresponding to La and Fe atoms in the prepared LaFeO3 sample. The weak ferromagnetic relaxation with finite coercivity (0.18248 kOe) and remanent magnetization (0.2825 emu. g−1) was estimated from M–H curve analysis using VSM data at room temperature. [ABSTRACT FROM AUTHOR]

The reaction of [(dpp-bian)Yb(DME)2] with one equivalent of dpp-bian and one equivalent of potassium or sodium gave the ate complexes [(dpp-bian)2Yb][K(DME)4] and [(dpp-bian)2Yb][Na(THF)6]. The reaction of [(dpp-bian)YbI(DME)]2 with potassium cyclopentadienide (CpK) led to the complex [{(dpp-bian)CpYb(μ-Cp)· K(Et2O)2}2(μ-Cp)2Yb(THF)2]. In all three compounds, the redox-active dpp-bian exhibits a dianionic state. Yb3+ cations in the prepared compounds determine their paramagnetism. Despite this, resolved 1H and 13C NMR spectra were obtained for [(dpp-bian)2Yb][K(DME)4] and [(dpp-bian)2Yb][Na(THF)6] in THF-d8, which made it possible to assign observed signals. The new compounds were characterized by IR and NMR spectroscopy and elemental analysis (C, H, N). The molecular structure of the prepared complexes was determined by X-ray diffraction [ABSTRACT FROM AUTHOR]

Present work focuses to investigate the impact of rare earth ions (Ce and Gd) on the structural and magnetic properties of nanocrystalline nickel-zinc ferrite. The nanoparticles of Ni0.5Zn0.5Fe2O4, Ni0.5Zn0.5Ce0.02Fe1.98O4, and Ni0.5Zn0.5Gd0.02Fe1.98O4 were synthesized by citric acid–assisted sol–gel method. The formation of cubic spinel structure without additional impurity peaks was confirmed by X-ray diffraction (XRD) pattern. The crystallite size of Ni0.5Zn0.5Fe2O4 (R = 0) and Ni0.5Zn0.5R0.02Fe1.98O4 (R = Ce and Gd) nanoparticles was observed less than ~ 35 nm at sintering temperatures of ~ 300 to ~ 500 ℃. From magnetic measurements, the value of room temperature saturation magnetization of superparamagnetic Ni0.5Zn0.5Fe2O4 (R = 0) was found to be reduced with the doping of Ce and Gd ions from 44.19 ± 0.02 to 39.33 ± 0.03 emu/g and 35.18 ± 0.02 emu/g, respectively, at 300 ℃ and from 60.69 ± 0.04 to 54.11 ± 0.03 emu/g and 55.72 ± 0.04 emu/g, respectively, at 500 ℃. The detailed study of superparamagnetic relaxation in pure and rare earth-doped samples was performed by the thermal magnetization measurements under zero field cool (ZFC) and field cool (FC) processes. Mossbauer spectra revealed the absence of the quadrupole splitting for Ni0.5Zn0.5Ce0.02Fe1.98O4 at tetrahedral (A-site) and octahedral (B-site) sites which indicated cubic symmetry in the crystal structure. Although, the presence of negative asymmetry was observed in Ni0.5Zn0.5Gd0.02Fe1.98O4-doped ferrite sample. Magnetic materials with superparamagnetic properties are desirable in various biomedical applications. [ABSTRACT FROM AUTHOR]

Nanocarriers of anticancer drugs are delicately designed with precision addition at every attempt. In this paper, we report CuCo2S4 nanoparticles that show light absorption in the near infrared-II wavelength range and possess magnetic characteristics. The synthesized nanoparticles are characterized by X-ray diffraction, Scanning Electron Microscopy, Dynamic Light Scattering, Thermogravimetry, and X-ray Photoelectron spectroscopy methods. The nanoparticles form a composite with biocompatible polymeric β-cyclodextrin. The nanoparticles possess a band gap energy of 2.25 eV. The magnetic property arises due to the cobalt incorporation in the nanoparticles. The anticancer drug camptothecin is loaded in the nanocarrier with an 89% adsorption efficiency. The in vitro release of the drug occurs in a sustained fashion. Further, the in vitro anticancer potential of the nanocarrier is examined on breast cancer (MDA-MB-231) cell lines, and the activities of the free- and the drug-loaded nanocarrier is compared. The cobalt-containing copper sulfide nanoparticle-poly-β-cyclodextrin composite works as a promising nanocarrier of camptothecin. [ABSTRACT FROM AUTHOR]

Ni0.5Zn0.5Fe2O4 ferrite nanoparticles were synthesized by high-energy ball-milling using binary oxide precursors, followed by a subsequent heat treatment at comparatively lower temperature (500 °C for 1 h) to promote the redistribution of the cations to their equilibrium positions. Although, several articles are available on Ni–Zn ferrite nanoparticles, the magnetic data of ball-milled sample has hardly been analysed based on existing theoretical models to extract useful information. The samples were characterized by X-ray diffraction, scanning electron microscopy and dc magnetization study. The average crystallite sizes estimated from the structural data (using Scherrer equation) are found to be around 14.4 nm. The temperature and field variation of magnetic data suggests a superparamagnetic nature with a distribution of particle sizes. The zero field cooled and field cooled magnetization data are analysed based on a theoretical model of superparamagnetic particles with a log-normal distribution, resulting in an average particle size of 24.4 nm (width parameter of 0.23). The Langevin function adequately describes the field variation of magnetization (M–H) data at room temperature, in addition to a paramagnetic contribution, suggesting the existence of significant spin disorder. The above fit yields an average magnetic moment of 7860 μ B . The results of the magnetic study corroborate well with the structural and morphological characteristics. [ABSTRACT FROM AUTHOR]

Local spin correlation orders emerge in a paramagnetic state, with notable examples such as the partial order, cooperative paramagnetism, and soliton spin liquid. The noncentrosymmetric intermetallic antiferromagnet Mn3RhSi also exhibits the local spin correlation order in the paramagnetic state as magnetic short-range order in a wide temperature range. Here, we show that the local spin correlation order has a spiral structure by neutron scattering measurement of a Mn3RhSi single crystal. The possible origins of the magnetic cluster formation are discussed in terms of the Lifshitz invariant and the Griffiths phase, and compared with the room-temperature skyrmion phase of Co7Zn7Mn6 and non-Fermi liquid behavior of β-Mn. Short-range magnetic orders emerge in a paramagnetic state, with notable examples such as the partial order, cooperative paramagnetism, and soliton spin liquid. Here, the authors use inelastic neutron scattering to investigate short-range magnetic order in Mn3RhSi single crystal finding evidence for a spin spiral cluster, which they suggest may be an origin of the anomalous physical property. [ABSTRACT FROM AUTHOR]

An analytical expression is found for the transverse dielectric permittivity of a nondegenerate electron plasma in the approximation of the effective collision frequency for a weakly nonideal gas, taking into account electron spin. The resulting expression takes into account both Landau diamagnetism and Pauli paramagnetism in an electron plasma. [ABSTRACT FROM AUTHOR]

We study the high and low-temperature thermo-statistical properties of ideal Fermi gases by taking into account the effect of generalized uncertainty principle (GUP). Starting with the logarithm of the grand partition function of ideal Fermi system, we derive the total number of particles, internal energy, entropy, and heat capacity under the GUP. For high temperatures, by obtaining a virial expansion of the equation of state of the system, the fist three virial coefficients are calculated. For low temperatures, by using the chemical potential of the system, the susceptibility for Pauli paramagnetism is derived. [ABSTRACT FROM AUTHOR]

Superparamagnetic iron oxide nanoparticles (SPIONs) coated with the synthetic hydrophilic biocompatible polymer polyvinyl alcohol were synthesized using the aqueous method. Static and dynamic magnetization processes were investigated for surface-modified SPIONs by analyzing the magnetization study at constant and varying magnetic fields. The magnetization on the applied magnetic field (M–H) and the magnetization dependent on temperature (M–T) were investigated. The temperature dependence of the complex susceptibility of SPIONs was investigated by measuring the in-phase (natural) and out-of-phase (imaginary) components of the susceptibility value at a frequency of 10 Hz and a very low magnetizing field. The XRD study shows diffraction peaks consistent with the magnetite (Fe3O4) phase of SPIONPs. FTIR, DSC, and TGA studies confirm the functional groups and stability of the coated nanoparticles. The magnetizing field cycle study at various constant temperatures (10, 100, and 300 K) shows the high magnetization value of polyvinyl alcohol-coated SPIONs with superparamagnetic states at and above 300 K. The effect of interparticle interaction on blocking temperature has been interpreted from FC/ZFC curves drawn at different DC magnetizing field values by varying temperature between 10 and 300 K. [ABSTRACT FROM AUTHOR]

The Blume-Capel Ising model has been investigated in the framework of developed mean field theory for a decorated ferrimagnet of two interprenetrating lattices. Based on certain variations of the spin crystal fields, novel features of long-range orders have been obtained in this research paper. Particularly, for a decorated square lattice consisting of spin-3/2 and decorating spin-5/2 ions on the bonds, characteristic results have been obtained. For the present system, many ferrimagnetic compensation temperatures were induced. It is worth to note that the contribution of the total magnetization to the superparamagnetism phenomenon production of a decorated mixed spin ferrimagnet with J 1 = - 0.5 , J 2 = - 1.0 , has been indicated as well. So, characteristic total magnetization behaviors in the (M , D B / J 2) space have not previously been considered. [ABSTRACT FROM AUTHOR]

Bi2Se3 has drawn great attention in current research for its novel topological property. In this literature, we establish the variation in structural, elemental, magnetic, and magneto-transport properties of Bi2Se3 due to the influence of Fe-doping. A solid-state synthesis mechanism has been used for the preparation of doped and un-doped Bi2Se3. Rietveld refinement of XRD data reveals the existence of Bi-substitution by Fe for low doping concentration. However, for high Fe-doping, there exists substitution of Bi as well as interstitial incorporation of Fe in host Bi2Se3. The XPS and SEM–EDX analysis also justify that Fe enters substitutionally for Bi and interstitial positions. From the magnetism study we have claimed that Fe-doped Bi2Se3 shows paramagnetism globally with local anti-ferromagnetism among Fe-dopants without long-range magnetic order. Based on electrical-transport survey we notice an increment of residual resistivity ( ρ 0) along with prominent anomaly in ρ xx –T profile around 120 K for high Fe-doping signifies the increment of carriers scattering. More importantly, there exists a gradual deviation of host quantum character, weak anti-localization (WAL) effect upon magnetic Fe-doping through the evidence of magneto-transport analysis. [ABSTRACT FROM AUTHOR]

The effect of bismuth ferrite (BiFeO3) nanoparticles (~ 20 nm) on Bi1.6Pb0.4Sr2Ca2Cu3O10 (Bi-2223) superconductor was studied. Bi-2223 powders with starting formula Bi1.6Pb0.4Sr2Ca2Cu3O10(BiFeO3)x for x = 0–0.20 wt.% were prepared using the co-precipitation method. The temperature dependent electrical resistance measurements showed the highest superconducting transition temperature for the x = 0.10 wt. % sample (Tc-onset = 118 K, Tc-zero = 106 K). The highest transport critical current density, Jct at 40 K was shown by the x = 0.02 wt. % sample (21.93 A cm−2). The peak temperature of imaginary part of susceptibility, Tp was much higher compared with the non-added sample, indicating BiFeO3 nanoparticles enhanced the flux pinning energy and intergranular coupling. The addition of a small amount of BiFeO3 nanoparticles (0.02–0.04% wt.%) increased the transport critical current density while further additions (0.06–0.20 wt.%) improved the superconducting transition temperatures. BiFeO3 nanoparticles slightly suppressed the formation of the Bi-2223 phase, but it increased the transport critical current density by more than eleven times demonstrating BFO could act as effective pinning centres and enhanced connectivity between grains. This work showed that BiFeO3 was better than other nanoparticles such as Ni0.5Zn0.5Fe2O4, Cr2O3, NiFe2O4, MgO, ZnO and Co3O4 in improving the transition temperatures and critical current density of the Bi-2223 phase superconductor. [ABSTRACT FROM AUTHOR]

The production of one-dimensional nanorods (NRs) has been capturing decent curiosity due to the peculiar electronic, spintronic, and hydrogen evolution properties. Consequently, herein, diluted magnetic semiconducting ZnO:V (0, 1, and 2 at%) NRs have been prepared through a typical hydrothermal method. SEM images depicted that the prepared samples belonged to nanorods. V ion incorporation into the ZnO matrix was confirmed through XRD, Raman, and XPS studies. A trivial decreasing of optical band gap with the V doping was determined via Kubelka–Munk plots. The doping enhances the paramagnetic nature of ZnO as function of V doping. Importantly, these NRs were measured for H2 production through H2O splitting by the solar simulator. The ZnO:V (2 at%) portrayed the best H2 production capability (25,188 µmol h−1 g−1) in 5 h than other samples. The plausible reasons behind the improved H2 evolution could be discussed in detail. Till date, this is the first ever report on H2 evolution of ZnO:V nanorods. [ABSTRACT FROM AUTHOR]

Two unique spinel compounds of type NiRh2S4 and RhNi2S4 crystal structure with chemical formula AB2X4 (A = Ni, Rh; B = Rh, Ni; and X = S) are chosen for the first time due to their importance in catalyst reactions and interesting physical properties to explore their structural, mechanical, electronic, and magnetic properties. First principle treatment has been implemented for the above-mentioned compounds with full potential linearized augmented plane wave plus local orbital methods (FPLAPW + LO) within the exchange correlation potentials range of state of the art density functional theory (DFT). The results obtained for the structural properties of these compounds using GGA approximation are compared with already available experimental results in the literature. Our spotted lattice constants for NiRh2S4 and RhNi2S4 are found to be consistent with experiment. Additionally we have also implemented the GGA + U potential for the improvements of electronic and magnetic characteristics of the compounds under investigation. Centered on the magneto-electronic properties, these compounds are metallic and paramagnetic in nature. Moreover, the crystal field splitting and the elastic properties of NiRh2S4 and RhNi2S4 are also discovered. The studies reveal that these compounds are elastically stable and ductile in character. Metallic characteristics and paramagnetic behavior of the compounds under observation predict their importance in spintronic and acoustical devices. [ABSTRACT FROM AUTHOR]

We present a theoretical study on the anisotropic magnetocaloric effect and the size-dependent magnetic properties of Fe particles of radii in the range 25–150 Å. An observable increase has been found in the magnetization, of the low radii (25–75 Å) particles, by reducing the temperature to 4 K. The anisotropic isothermal change in entropy ΔSm has been calculated by taking the difference between maximum ΔSm along the easy [100] and hard [111] directions. The maximum anisotropic ΔSm is 0.015 J/kg K for a field change of 500 Oe along the [100] direction. The ΔSm temperature dependence exhibits a table-like plateau for small radii (25–75 Å) and in low fields below 300Oe. This enhances the relative cooling power (RCP) of the Fe element to be 8.11 J/kg for particles of 25 Å radius. Also, the calculation of anisotropic ΔTad was performed along the easy axis and showed an increase in the maximum value around 37% relative to the experimental conventional value. [ABSTRACT FROM AUTHOR]

Tin-doped zinc sulfide was coated onto glass plates and subjected to a post-air annealing treatment at 300 °C for 2 h. The air-annealed thin films were characterized for observing the tailoring in structural, surface, chemical, optical, photoluminescence, and magnetic properties due to annealing. The properties of thin films after air-annealing were compared with as-synthesized Kumar et al. (J. Supercond. Novel Magn. 32(6), 1725-1734, 2019), and vacuum-annealed Kunapalli et al. (Opt. Mater.114, 110961, 2021) thin films. Annealing in presence of air leads to finer crystallite structures of ZnS thin films. The air annealing also enhanced the transmittance property of the thin films. Two prominent peaks at 420 nm and 440 nm were observed in photoluminescence spectra. From magnetic studies, it was found that the films were paramagnetic in nature, and magnetization increased with an increase in the applied field. [ABSTRACT FROM AUTHOR]

Iron oxide nanoparticles coated with polyethylene glycol were synthesized by coprecipitation for use in the magnetic separation of DNA (deoxyribonucleic acid). The blocking temperature of nanoparticles was studied by the methods of Mössbauer spectroscopy, ferromagnetic resonance, and using magnetometric measurements. The blocking temperature calculated from the temperature dependence of the coercive force was ~ 200 K. The calculation of the blocking temperature from the relaxation time obtained using Mössbauer spectroscopy gave a value of ~ 450 K. The blocking temperature obtained using ferromagnetic resonance was ~ 910 K. The relationship between the obtained blocking temperatures is in good agreement with the Néel-Brown formula. The constants of effective and surface anisotropy were determined by the method of ferromagnetic resonance. Isolation of DNA from blood using prepared particles and separation in a permanent magnet field revealed sufficient productivity, high speed, and the "chemical delicacy" of this approach. [ABSTRACT FROM AUTHOR]

Inspired by the multi-functionalities of vegetal extracts, we first focused on developing a new gold nanoparticle (AuNP) synthesis method using tomato extract (Solanum lycopersicum Mill, Carmen variety) under conditions in which proteins could be preserved and unexpected additional synthesis of superparamagnetic magnetite occurred. The AuNPs and magnetite were characterized by UV–visible spectroscopy, dynamic light scattering, superconducting quantum interference device, high-resolution transmission microscopy and energy-dispersive X-ray spectroscopy. Based on the literature, the ferrihydrite core of holoferritin was postulated to be the magnetite precursor. Consistently, the tomato genome encodes a protein homologous to ferritin and an identical result was obtained with purified horse spleen ferritin (HSF). The electron paramagnetic resonance spectrum of the lyophilized tomato pulp extract at 298 K featured HSF signal with (g0 = 2.070). This signal is absent in another tomato variety (Solanum lycopersicum, cherry variety), as well as in the boiled Carmen tomato extract, which produced only AuNPs after stirring with HAuCl4. The synthesis of magnetite in an air atmosphere is feasible only using holoferritin because the synthesis by loading apoferritin with iron salt requires an inert atmosphere and controlled stoichiometry. In addition, AuNPs produced by this method exhibited potential for use in photodynamic therapy. [ABSTRACT FROM AUTHOR]

Magnetic susceptibility measurements are often the first characterization tool that researchers turn to when beginning to assess the magnetic nature of a newly discovered material. Breakthroughs in instrumentation have made the collection of high quality magnetic susceptibility data more accessible than ever before. However, the analysis of susceptibility data remains a common challenge for newcomers to the field of magnetism. While a comprehensive treatment of the theoretical aspects of magnetism are found in numerous excellent textbooks, there is a gap at the point of practical application. We were inspired by this obstacle to put together this guide to the analysis and interpretation of magnetic susceptibility data, with an emphasis on materials that exhibit Curie-Weiss paramagnetism. Magnetic susceptibility measurements are an integral technique used across chemistry, physics and materials science; however, while straightforward to perform, interpretation of the data is often not. Here, the authors provide a basic guide to help newcomers interpret magnetic susceptibility data outlining examples based around the Curie-Weiss law that are ideal for those wishing to learn the basics of this method. [ABSTRACT FROM AUTHOR]

A computer modeling (DFT UTPSSh/6-311++G(d,p)) of electronic structures, geometric parameters, energy characteristics, and magnetic properties of the mononuclear cobalt complexes with tetradentate N-donor bases (tris(2-pyridylmethyl)amines and N,N'-dialkyl-2,11-diaza[3.3]-(2,6)pyridinophanes) and o-benzoquinones comprising triangulene organosilicon radicals was performed. Paramagnetism of all states of the studied molecules is predicted. It is ascertained that the electronic configurations and energy characteristics of the isomers of the complexes under study are controlled by alkyl substituents in the ancillary N-donor ligands. The compounds capable of manifesting thermally initiated spin state switching rearrangements via spin-crossover and valence tautomerism mechanisms are revealed. [ABSTRACT FROM AUTHOR]

This paper reports a potential and easy method to prepare nickel ferrite nanoparticles with improved dielectric and magnetic properties by doping with zinc. The structural studies and Rietveld refinement of the XRD pattern confirm the cubic spinel structure of the ferrite phase belonging to the Fd3m space group. Morphological and elemental composition analyses of the prepared samples are carried out using scanning electron microscopy and energy dispersive spectroscopy (EDAX). The frequency variation of the dielectric constant and ac conductivity have been studied. The dependence of dielectric constant and ac conductivity on the frequency of the alternating applied electric field is explained by the Maxwell–Wagner model. The zinc doping in nickel ferrite nanoparticles is helpful in modifying the dielectric properties and thereby designing materials matching the application requirements. Magnetic measurements were carried out at 300 K and 5 K points toward an enhanced magnetic property in zinc-doped samples. The saturation magnetization value for zinc ferrite nanoparticles is around 23 emu/g at 300 K and 56 emu/g at 5 K which clearly indicates the superparamagnetic behavior of the samples. The maximum value for Ms is obtained for the Ni0.5Zn0.5Fe2O4 sample which is 74 emu/g and 101 emu/g at 300 and 5 K, respectively. The enhanced dielectric and magnetic properties inherited by Zn doping in nickel ferrite (NFO) nanoparticles suggest the improved potential of these superparamagnetic NZFO nanoparticles for various applications. [ABSTRACT FROM AUTHOR]

Troponin I, as a cardiac-specific biomarker, is a very valuable tool in the identification of acute coronary syndromes. In this work, an economical technique for easy and sensitive diagnosis of cardiac troponin I (cTnI) was developed nanoprobe on the basis of graphene oxide quenching of the fluorescence of bovine serum albumin–capped fluorescent nickel (BSA@NiNCs) nanoclusters. The developed nanoprobe nickel nanocluster exhibited superparamagnetism. The nanoprobe showed a fluorescence turn-on behavior toward incremental addition of in cTnI, with a detection limit of 0.012 ng/mL. We successfully used the proposed sensing technique for cTnI sensing in serum samples. [ABSTRACT FROM AUTHOR]

Dirac matters have attracted a lot of interest due to their unique band structure with linear band dispersions, which have great potential for technological applications. Recently, three-dimensional Dirac and Weyl semimetals have invoked distinctive phenomena originating from a non-trivial Berry phase. In this study, we prepare single crystals of TixZr1-xTe5 with a highly anisotropic Fermi surface. Our detailed electrical transport measurements reveal that the crystals show the Lifshitz transition, and Ti doping induces a band shift. Further quantum oscillation analyses demonstrate that the TixZr1-xTe5 crystals are 3D Dirac semimetals. Additionally, we observed a minimum temperature-dependent magnetic susceptibility, which is close to a peak position of electrical resistivity. This observation is interpreted in terms of the Berry paramagnetism. Our finding paves the way to determine a band topology by magnetism and also provides a platform to apply the Berry magnetism to Dirac semimetals. Topologically non-trivial materials demonstrate a range of exotic electronic phases related to the Berry phase of the system and recent investigations are also considering the magnetic properties in order to further enrich the physics of these materials. Here, the authors perform electronic transport and magnetization measurements on single crystals of Ti-doped ZrTe5 revealing them to be 3D Dirac semimetals that may also exhibit Berry paramagnetism. [ABSTRACT FROM AUTHOR]

The magnetic properties of magnetite nanoparticles (Fe3O4 NPs) strongly depend on their chemical and physical parameters, which can be regulated by a controlled synthesis process. To improve the quality of the obtained nanoparticles, their surface is often modified with organic compounds (from the group of surfactants, sugars, proteins, or organic acid). In this study, we synthesized magnetite nanoparticles with a surface modified with the organic compound DMSA. Then, the nanocrystallites were characterized in terms of structure and morphology. To investigate the role of DMSA and to understand the adsorption mechanism, FTIR measurements were carried out. Using Mössbauer spectroscopy, we investigated temperature-induced changes in the magnetic properties of prepared samples. The spectra were recorded in a wide temperature range (from 4 K to 390 K) for two types of samples: powders and ferrofluids with various concentrations. In the case of powder samples, the superparamagnetic doublet appeared at room temperature. For magnetic suspensions, the spectra were more complicated. They consisted of superposition of asymmetrically broadened sextets and doublets, which was caused by the occurrence of long-range dipole-dipole interactions. These interactions affected the magnetic properties of the material and increased the blocking temperature. Additionally, the magnetic hysteresis and zero field cooling-field cooling (ZFC/FC) curves were measured with the use of a vibrating sample magnetometer. [ABSTRACT FROM AUTHOR]

Magnetic susceptibility (MS) as a fast, non-destructive, and reasonable technique is very useful in soil genesis and evolution studies. The MS of soils along a climolithotoposequence in Jazmoorian Watershed was studied in the present research and the vertical distribution of MS in the representative pedons affected by soil forming factors (parent material, climate and relief) was also investigated. Rock pediment, mantled pediment, piedmont plain, alluvial fan, and playa geomorphic positions with two igneous (gabbro, diorite, granite, and andesite) and sedimentary (limestone, conglomerate and playa deposits) parent materials were selected. Thirteen representative pedons which best reflected the variations of soil forming factors were studied. Results of the study showed that the maximum (877.8 × 10−8 m3 kg−1) and the minimum (5.2 × 10−8 m3 kg−1) low frequency (χlf) MS were respectively determined in the soils formed on igneous and sedimentary parent materials. The χlf values were increased with depth in soils affected by igneous parent material, but the opposite trend was found in soils with a sedimentary origin. The activity ratio of Feo/Fed in xeric and aridic moisture regimes were 0.03 and 0.09, respectively. Meanwhile, MS value in surface soil of pedon 2 (with xeric moisture regime) is lower than its parent material which is a support for the higher weathering of this soil due to higher moisture compared to pedon 5 with an aridic moisture regime. Decreasing evolution trend of soils on igneous parent material was in the order of alluvial fan < piedmont plain < mantled pediment, but in the soils on sedimentary parent material was in the order of playa < rock pediment < mantled pediment < alluvial fan. Results of the study clearly showed that the soil χlf values changed with variations in climate, parent material, and topography. [ABSTRACT FROM AUTHOR]

Strong room temperature superparamagnetic properties have been achieved in Zn0.94Li0.03Fe0.03O nanoparticles within a magnetic field of ± 20,000 Oe. High-purity ZnO, Zn0.97Li0.03O, Zn0.94Li0.03Mn0.03O, and Zn0.94Li0.03Fe0.03O nanostructures were synthesized by means of the coprecipitation method. The XRD crystallographic planes and HRTEM of the synthesized compositions showed that a single phase of a ZnO hexagonal wurtzite structure was obtained with the absence of any secondary phases or magnetic cluster. Pure ZnO powders show asymmetrical nanoparticles with a certain degree of agglomeration and approximately have an average particle size of 37 nm. The TEM image of Li-monodoped ZnO powders displays uniform spherical nanoparticles with less agglomeration, and the average particle size was reduced to 35 nm. The image of the (Li, Mn) codoped ZnO sample illustrates that the particles of ZnO are transformed to elongated shapes without agglomeration with an average particle size of 32 nm. In case of (Li, Fe) codoped ZnO powders, the image clearly shows a mixture of uniform nanospherical and elongated particles with a small average particle size of 27 nm. The absorption edge of ZnO is red shifted to more wavelength absorption due to (Li, Mn) and (Li, Fe) codoping, and it becomes sharper after Li monodoping which is a dynamic factor in the optoelectronic applications. Interestingly, the Zn0.94Li0.03Fe0.03O composition exhibits a superparamagnetic behavior at room temperature; it obviously shows a semi-saturation magnetization of 0.02 emu/g but has a nearly very small coercivity of 14 Oe. The instantaneous presence of both ferromagnetism and antiferromagnetism in Zn0.94Li0.03Fe0.03O gives rise to the disordered state of superparamagnetism. [ABSTRACT FROM AUTHOR]

Mössbauer spectra of Feridex, an MRI enhancement agent, show that it contains superparamagnetic γ-Fe2O3 nanoparticles. From spectra in magnetic fields applied at room temperature the magnetic moment of the particles was measured to be 11,250 μB, from which the diameters of the single-domain particles are estimated to be about 8 nm. This is smaller than the hydrodynamic particle size of 30 nm which includes a protective coating of dextran. The particles are monodisperse, as shown by the continuous change from a broad superparamagnetic line to a magnetic 6-line pattern as the temperature is lowered below the blocking temperature TB of about 90 K. The magnetic moments and blocking temperature are consistent with those of γ-Fe2O3 samples of known sizes. [ABSTRACT FROM AUTHOR]

In this study, a new and systematic approach was taken to study the effect of morphology on the magnetic properties of magnetite nanoparticles. A simple hydrothermal method was used to synthesize spherical, cubic, and rod-shaped nanoparticles. For this purpose, homogeneous solutions of heptahydrate ferro sulfate, deionized water, polyethylene glycol, ammonia, hydrogen peroxide, and alcohol were first made in different proportions. The resulting solutions were heated in an autoclave at 160°C for 5 h to allow the nucleation and growth of the magnetite nanoparticles. The resulting precipitates were then filtered, washed, and dried at 80°C. XRD was utilized to study the phase formation of the synthesized samples and their crystallite size. The morphology of the samples and the particle size were studied using SEM. VSM was used to investigate the magnetic properties. The results showed that spherical, cubic, and rod-shaped magnetite nanoparticles were successfully synthesized without any XRD detectable impurities with the present scan conditions. The crystallite size of the spherical, cubic, and rod-like powders was calculated to be about 17, 22, and 8 nm, respectively, while the average particle size was about 25, 63, and 12 nm, respectively, indicating the polycrystalline nature of the particles, i.e., the particles consisted of many crystallites. All the samples, regardless of the morphology, showed superparmagnetic properties. Magnetite nanoparticles with cubic morphology showed a higher Ms value than the others, while the rod-like nanoparticles exhibited the lowest Ms value. The magnetic saturation values were 60.74, 66.36, and 35.11 emu g−1 for the spherical, cubic, and rod-like particles, respectively. [ABSTRACT FROM AUTHOR]

We investigate the propagation characteristics of nonlinear kinetic Alfven waves in quantum plasma with effects of Pauli paramagnetism and degeneracy temperature. In an arbitrary amplitude regime, we derive the energy integral equation by employing the quantum magnetohydrodynamic model. From the graphical analysis, it is found that the width of soliton structure decreases by enhancing the value of factor χ = T e / T F for nearly degenerate plasma state and increases by increasing the value of factor z = exp (μ / k B T e) for nearly non-degenerate plasma state, while there is no change in its amplitude. Moreover, it is also revealed that by changing the value of magnetic field strength H the width of the nonlinear structure is modified more in case of nearly degenerate plasma state as compared to a nearly non-degenerate plasma state with no change in its amplitude. The importance of the present work to astrophysical plasmas such as white dwarfs and neutron stars is also highlighted. [ABSTRACT FROM AUTHOR]

We report the experimental observation of and theoretical explanation for the reduction of dopant ions and enhancement of magnetic properties in Ce-doped TiO2 diluted magnetic semiconductors from UV-light irradiation. Substantial increase in Ce3+ concentration and creation of oxygen vacancy defects in the sample due to UV-light irradiation was observed by X-ray and optical methods. Magnetic measurements demonstrate a combination of paramagnetism and ferromagnetism up to room temperatures in all samples. The magnetization of both paramagnetic and ferromagnetic components was observed to be dramatically enhanced in the irradiated sample. First-principle theoretical calculations show that valence holes created by UV irradiation can substantially lower the formation energy of oxygen vacancies. While the electron spin densities for defect states near oxygen vacancies in pure TiO2 are in antiferromagnetic orientation, they are in ferromagnetic orientations in Ce-doped TiO2. Therefore, the ferromagnetically-oriented spin densities near oxygen vacancies created by UV irradiation are the most probable cause for the experimentally observed enhancement of magnetism in the irradiated Ce-doped TiO2. [ABSTRACT FROM AUTHOR]

Fe–Ni nanoparticles are attractive candidates for magnetic cores of transformers and inductors that are operated at high frequencies. When applying Fe–Ni nanoparticles in magnetic cores, particle size must be controlled to enhance magnetic properties. A two-step synthetic method can be useful for fabricating size-controlled Fe–Ni nanoparticles. In the first step, Ni nanoparticles are synthesized by reducing Ni (II) acetylacetonate in oleylamine (OA) with trioctylphosphine (TOP). Thereafter, Fe (III) acetylacetonate is reduced and Fe atoms diffuse into the preformed Ni nanoparticles in OA. The size of the Fe–Ni nanoparticles depends on that of the Ni nanoparticles. However, no studies have conducted extensive investigations of their synthesis and magnetic properties with various particle sizes. Here, we attempted particle-size-controlled synthesis of Fe–Ni nanoparticles and investigated their magnetic properties. The particle size of the Fe–Ni nanoparticles was varied between 13.1. and 20.5 nm by varying the size of Ni nanoparticles. The saturation magnetization (Ms) gradually reduced with the decrease in particle size because of the increased amount of oxidized surface atoms and phosphides. Coercive forces (Hc) also decreased as the particle size decreased to 15 nm because of the increased effect of superparamagnetism, while the Hc greatly increased with the particle size reduction below 14 nm because of the ferromagnetism exhibited by the Fe layer owing to undiffused Fe atoms. Thus, using this synthetic method, Fe–Ni nanoparticles with a size of approximately 15 nm can be produced, which have a minimum Hc and are the most appropriate for magnetic cores. [ABSTRACT FROM AUTHOR]

We present a comparative study on superparamagnetic uncoated and silica-coated NiFe2O4@SiO2 nanoparticles with identical NiFe2O4 cores and two different silica coating thicknesses, focusing on the surface spin arrangement on NiFe2O4. For the investigation of surface spin dynamics, in addition to the SQUID magnetometry experiments which probe the macroscopic behaviour of particle magnetization, Mössbauer spectroscopy was utilized as being a local technique with superior characteristic measurement time. It was revealed that two common aspects observed in nanoscaled magnetic particles, namely the surface spin canting and interparticle dipolar interactions, are intertwined with respect to their contributions to the total magnetic anisotropy, where the latter is significantly decreased with silica coating thickness and allowed surface effects to manifest itself in Mössbauer spectra. The reduced saturation magnetization of uncoated NiFe2O4 nanoparticles with respect to their bulk counterparts indicated the existence of a "magnetically dead" layer on NiFe2O4 surface. In opposite to some assumptions in the literature, the Mössbauer spectra confirmed that such reduced magnetization arises from spin disorder, rather than a change in coordination from inverse spinel to the mixed spinel structure. On the other side, emergence of broad sextet peaks at room temperature Mössbauer spectra showed that for NiFe2O4@SiO2 samples, silica coating further enhanced the spin canting on NiFe2O4 surface. Similarly, for NiFe2O4@SiO2 sample, an unusual asymmetric hysteresis loop at spin freezing temperature was observed as a signature of the existence of disordered spins in the SiO2/NiFe2O4 interface. It was shown that the sextet components in Mössbauer spectra can be reproduced with a continuous hyperfine field distribution due to the frustrated local spin arrangement at the surface. The thickness of the "magnetically dead" disordered surface spin layer was estimated for uncoated NiFe2O4, and average spin canting angle was calculated for NiFe2O4@SiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

The heating characteristics of ferrite nanoparticles are inconsistent due to various factors that affect the optimum particle size required for maximum power dissipation. The heating mechanism of Fe3O4, MnFe2O4, and Co0.5Fe2.5O4 in the size range 10–40 nm with varying particle size distribution is correlated with the effective specific absorption rate (ESAR). The effective magnetic anisotropy of the ferrite samples determined using electron spin resonance is between 11.8 and 24.8 kJ· m−3. The thermal profiles of Fe3O4, MnFe2O4, and Co0.5Fe2.5O4 are probed employing infrared thermography where the measured ESAR is between 1.74 and 3.16 nHm2·kg−1. The theoretical ESAR of 16.63 and 9.19 nHm2·kg−1 are obtained for the Co substituted Fe3O4 and MnFe2O4, respectively, for an average size of 40 nm. The analysis of particle size distributions in combination with theoretical estimations gives the percentage of particles contributing to the power dissipation as 80 % for narrow dispersion and 45 % for broad dispersion deviating from the predicted optimum size range. In addition to ascertaining the functioning regime of the linear response theory, an increase in ESAR with decreasing anisotropy energy is observed. The discrepancy between the simulations and experimentations is prudently examined, taking the intrinsic as well as extrinsic parameters into account. [ABSTRACT FROM AUTHOR]

Zinc ferrite (ZnFe2O4) nanoparticles were prepared by chemical co-precipitation method. Structural characterization was performed using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Formation of spinel phase was confirmed from XRD studies. Crystallite size and lattice constant of the prepared sample were calculated. TEM images reveal spherical-shaped particles with nanosized distribution. Room temperature magnetic hysteresis loop was recorded using vibrating sample magnetometer (VSM). The magnetization loops exhibit a very narrow loop and behave like superparamagnetic nature. Using the Langevin function, the magnetic behaviour of the prepared nanoparticles was investigated. From the curve fitting, saturation magnetization and reduced magnetization were determined. As-prepared sample was further annealed at three different temperatures namely 800 °C, 1000 °C, and 1200 °C for 2-h duration. The effects of annealing on the structural and magnetic properties were further investigated using XRD and VSM. The observed results on the magnetic characteristics of ZnFe2O4 and applicability of the Langevin function are being discussed. [ABSTRACT FROM AUTHOR]

Fe3O4@Y2O3:Eu3+ nanocomposites and Y2O3:Eu3+ nanophosphors were synthesized using the hydrothermal method. Nanocomposites were analyzed using X-ray diffraction (XRD), Rietveld refinements, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, photoluminescence (PL), vibrating sample magnetometer (VSM), and high-resolution transmission electron microscopy (HRTEM). Nanocomposites exhibit superparamagnetic behavior that improves with Eu3+, resulting in increased magnetic saturation. In contrast to Y2O3:Eu3+ nanophosphors, the Fe3O4@Y2O3:Eu3+ nanocomposites display a distinctive characteristic whereby the photoluminescence intensity increases with a reduced concentration of Eu3+. The requirement of increasing the thickness of the Y2O3:Eu3+ outer layer to achieve improved light emission can be circumvented by solely manipulating the concentration of activators, without compromising the magnetic saturation of the nanocomposites. The luminescent and magnetic characteristics of Fe3O4@Y2O3:Eu3+ nanocomposites can be readily optimized using straightforward synthesis parameters, making them promising candidates for potential applications in theranostic medicine. [ABSTRACT FROM AUTHOR]

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

The 18-electron (η4-C4Me4)Co(CO)2TeI2Ph compound noticeably decomposes upon prolonged storage and also unusually transforms into the 17-electron (η4-C4Me4)CoI2(PhTeI) complex (I). The X-ray diffraction study of the molecular and crystal structures of complex I (CIF file CCDC no. 1991837) reveals interesting analogies with the molecular structures of the known metal complexes containing organotellurium halide ligands and with the crystal packing of the related one-component crystals of (η4-C4Me4)Co(СО)2TeI2Ph and (η4-C4Me4)Co(СО)2I and two-component crystals of (η4-C4Me4)Co(СО)2I–1,4-C6H4I2. An analysis of the crystal packing of molecules of complex I elucidates a new supramolecular synthone I···(η4-C4Me4) determining the structural motifs of self-assembly in complex I and related compounds (η4-C4Me4)Co(CO)2I, (η4-C4Me4)Co(CO)2I···1,4-C6H4I2, and (η4-C4Me4)Co(CO)2TeI2Ph. The EPR study of compound I shows that cobalt exists in the low-spin state with the total spin S = 1/2. [ABSTRACT FROM AUTHOR]

Computational modeling (DFT UB3LYP/6-311++G(d,p)) of the spatial structure, energy parameters, and magnetic properties of the adducts of fluorinated cobalt(II) bis-diketonates with o‑benzoquinones containing hydrosilicon triangulene moieties has been performed for the first time. Compounds potentially capable of thermally initiated redox-isomeric rearrangements have been revealed. It has been demonstrated that extension of the polycyclic moiety has no effect on the energy differences between the electromers, but leads to an increase in the total spin of the system. The presence of triangulene radical fragments and exchange coupling are responsible for paramagnetism of all the studied molecules. [ABSTRACT FROM AUTHOR]

Biocompatible magnetic nanoparticle-mediated magnetic hyperthermia is an innovative, efficient, and safer thermo-therapeutic approach for cancer treatment. Structural and magnetic properties of magnetic nanoparticles as well as external magnetic field parameters are responsible for a controlled heating performance imperative for clinical success. This review covers topics from the nanophysics of magnetic nanoparticles through the basic concepts of magnetism to the different magnetic nanoparticles used for magnetic hyperthermia. Relevant properties beneficial for magnetic hyperthermia including size (nanosize regime of 10–100 nm), shape (anisotropic and isotropic), viscosity of the dispersive medium, and applied magnetic field parameters to optimize the heat dissipation via various mechanisms are also addressed. Primary aim of the present review is to provide an interdisciplinary knowledge platform for the basic understanding of nanomagnetism in order to advance further in the field of nanomedicine. This review pinpoints recent advancements in nanoparticle-tumor tissue interactions and their translation to clinical applications. The present review differs from other contemporary reviews by reporting the up-to-date developments in the nanotechnology aspects of magnetic hyperthermia and addressing the future perspectives. [ABSTRACT FROM AUTHOR]

The structural, optical and magnetic properties of nanorod structured polycrystalline Zn1−xMnxO3 films 0 ≤ x ≤ 0.1 grown on glass substrate using Sol–Gel technique have been investigated. X-ray diffraction (XRD) analysis reveals average grain sizes from 15 to 25 nm. There was gradual increase in both the crystallite size and lattice constant with increase in Mn content up to 0.2%, and then decrease of them with further increase in Mn content. The same result has been confirmed by SEM experiments. It has been revealed that the band gap value of Zn1−xMnxO film decreases from 3.34 to 2.97 eV with an increase in Mn concentration from x = 0.0 to 0.1, which is in agreement with the previously reported results. The studies of the magnetization and magnetic resonance of Zn1−xMnxO films revealed the presence of the paramagnetic state without any magnetic ordering. [ABSTRACT FROM AUTHOR]

Cobalt-doped zinc sulfide quantum dots with different cobalt concentrations were prepared by the solution route. Structural, optical, morphological, and magnetic responses of the prepared quantum dots were analyzed. X-ray diffraction study confirmed that cubic (zinc blende) structure is the dominant structure of synthesized samples. Crystallite size and lattice constant were found to decrease with cobalt dopant. Transmission electron microscope analysis shows that the mean size of the particles lies in the range of 7–10 nm. The absorption edge of cobalt-doped zinc sulfide nanoparticles is shifted to lower wavelength as compared to that of bulk zinc sulfide which confirmed the quantum confinement effect. The bandgap variation was observed with doping, and it varied from 4.3 to 5.6 eV. The emission spectrum reveals that the cobalt dopant suppresses the ultraviolet emission and enhances the visible emission. Fourier-transform infrared spectrum confirmed the formation of zinc sulfide and the substitution of cobalt ion. Magnetization versus magnetic field result demonstrates that the zinc sulfide and cobalt-doped zinc sulfides are superparamagnetic. Electron spin resonance spectra also confirmed the superparamagnetic nature of zinc sulfide and cobalt-doped zinc sulfide samples. Micro-Raman study also confirmed the incorporation of cobalt in the lattice and the size of the order of the exciton Bohr radius for ZnS. [ABSTRACT FROM AUTHOR]

The effects of Ta substitution on the first-order phase transition have been firstly studied in Hf1-xTaxFe2 (x = 0.15, 0.165, 0.18) alloys with kagome-type lattice. Higher Ta substitution leads to the reduced metamagnetic transition temperature (Tt) from low-temperature ferromagnetism to high-temperature antiferromagnetism and paramagnetism. By doping C atoms, the Tt is gradually reduced and thermal hysteresis becomes widened in the alloys with higher Ta substitution. The critical field which triggers the metamagnetic phase transition is not substantially affected by interstitial C atoms. With increased Ta substitution, for the field change of 7 T, the maximum of magnetic entropy change (ΔSmax) of 3.7 J kg−1 K−1 is obtained at x = 0.15 and enhanced to 4 J kg−1 K−1 at x = 0.165 but reduced to ~ 3.21 J kg−1 K−1 in Hf0.82Ta0.18Fe2 alloy. By C addition, both Tt and the temperature where ΔS is maximized are shifted to a lower temperature, especially in the higher Ta-contained alloys. [ABSTRACT FROM AUTHOR]

We have carried out a systematic study on the effect of high-temperature annealing on the structural and magnetic properties of ultra-small crystalline cobalt ferrite nanoparticles prepared by the hydrothermal method. The structural and the magnetic characterizations of nanoparticles were investigated by XRD, TEM, FTIR, and VSM. The results of Rietveld refinement revealed that the nanoparticles have a cubic single-phase spinel structure. High-temperature annealing was found to increase the lattice parameter and average crystallite size of the cobalt ferrite nanoparticles. The TEM measurements showed that the nanoparticles were monodisperse and spherical in shape. The FTIR results confirmed the single-phase nature of the prepared nanoparticles. The magnetic measurements showed that the nanoparticles were ferromagnetic over a wide temperature range. We have observed that the high-temperature annealing increased both the saturation magnetization and magnetocrystalline anisotropy and decreased the coercivity. We demonstrated that magnetic field induced superparamagnetism can be induced by applying stronger magnetic fields that were able to shift the blocking temperature (TB) down to below room temperature, resulting in a superparamagnetic behavior above TB. [ABSTRACT FROM AUTHOR]

We have synthesized Fex(Cu0.5In0.5)1– xCr2S4 solid solutions and measured their magnetic properties in the temperature range 4.2–300 K in a static magnetic field of 0.1 and 45 kOe. The main magnetostatic parameters of the synthesized materials have been determined: saturation magnetization, effective and spin magnetic moments, Curie and Néel temperatures, Curie constants, and Curie–Weiss constants. The results thus obtained, including the properties of magnetic clusters and the composition dependence of the asymptotic Curie temperature, have been interpreted using a previously reported magnetic phase diagram of the Fex(Cu0.5In0.5)1– xCr2S4 solid solutions, which provides insight into the nature of the phase transformations involved. [ABSTRACT FROM AUTHOR]

This paper shows that the mineral composition of dolerites affects their specific paramagnetic susceptibility. Two methods for calculating the specific paramagnetic susceptibility were proposed: one used the thermomagnetic analysis (TMA) curve and the other the Mi(B) curve. There was no significant difference between the results obtained with these two approaches. Application of the proposed methods to dolerite core samples showed that specific paramagnetic susceptibility can be used as the basis for correlation of sills. The composition of titanomagnetites in dolerites can be used as an accessory parameter. [ABSTRACT FROM AUTHOR]

The 2-dimensional Ising model on a square lattice is investigated with a variational autoencoder in the non-vanishing field case for the purpose of extracting the crossover region between the ferromagnetic and paramagnetic phases. The encoded latent variable space is found to provide suitable metrics for tracking the order and disorder in the Ising configurations that extends to the extraction of a crossover region in a way that is consistent with expectations. The extracted results achieve an exceptional prediction for the critical point as well as agreement with previously published results on the configurational magnetizations of the model. The performance of this method provides encouragement for the use of machine learning to extract meaningful structural information from complex physical systems where little a priori data is available. [ABSTRACT FROM AUTHOR]

The case of palladium(II) ions in molecular polyoxopalladates highlights the importance of accounting not only for nearest neighbour atoms or ions in order to understand, model or predict magnetic characteristics. Here, using site-specific soft X-ray magnetic circular dichroism (XMCD), the effects of different bond lengths, delocalization of 4d electrons, and 4d spin-orbit coupling on the electronic and magnetic properties are investigated and three different states identified: Conventional diamagnetism in a square-planar O4 coordination environment, paramagnetism caused by four additional out-of-plane oxygen anions, and an unusual diamagnetic state in the diamagnetic/paramagnetic crossover region modified by significant mixing of states and facilitated by the substantial 4d spin-orbit coupling. The two diamagnetic states can be distinguished by characteristic XMCD fine structures, thereby overcoming the common limitation of XMCD to ferro-/ferrimagnetic and paramagnetic materials in external magnetic fields. The qualitative interpretation of the results is corroborated by simulations based on charge transfer multiplet calculations and density functional theory results. Soft x-ray magnetic circular dichroism is typically used to study ferro- or paramagnetic materials, but not diamagnetism. Here XMCD fine structures are used to distinguish diamagnetic states in molecular polyoxopalladates in conjunction with theoretical calculations. [ABSTRACT FROM AUTHOR]

We have performed a systematic study on the effect of Zn substitution on the structural and magnetic properties of crystalline zinc-substituted cobalt ferrite nanoparticles, Zn x Co 1 - x Fe 2 O 4 with x = 0, 0.25, 0.5, 0.75, and 1, prepared by hydrothermal method. The structural and magnetic properties of these nanoparticles were investigated by XRD, TEM, FTIR, and VSM. All the ferrite nanoparticles were prepared with sizes smaller than 20 nm, thus lying within the range of single-domain regime. The results of Rietveld refinement revealed that all prepared nanoparticles were cubic and single phase, and the increase in Zn concentration resulted in an increase in the lattice constant, x-ray density, and the average bond length on tetrahedral sites. The TEM measurements showed that the nanoparticles were monodisperse and spherical in shape. All FTIR spectra of the prepared ferrites showed two dominant absorption bands, thus confirming the formation of single-phase spinel structure with two sub-lattices: tetrahedral (A-site) and octahedral (B-site). The room temperature M versus H magnetization measurements revealed that the ferrite nanoparticles were ferromagnetic for x = 0 and superparamagnetic for x ≥ 0.25 . At 10 K, all ferrite nanoparticles showed ferrimagnetic behavior that is weakened by Zn substitution. The saturation magnetization and the first anisotropy constant were observed to decrease with increasing Zn concentration. The zero field cooled and field cooled magnetization data revealed that both superparamagnetic and spin-glass like states may coexist together depending on amount of Zn concentration and temperature. [ABSTRACT FROM AUTHOR]

In this research work, iron-doped tin dioxide nanoparticles were successfully produced by high-energy ball-milling and their structural and magnetic properties were evaluated by means of room temperature X-ray diffraction, Mössbauer spectroscopy, and vibrating sample magnetometry. In order to evaluate the thermal stability of the compounds, samples were subjected to a thermal treatment and their structural and magnetic properties were studied. The nanoparticles were produced by processing SnO2 commercial powders together with doping amounts of Fe2O3 commercial powder in a high-energy planetary ball-mill. X-ray diffraction showed the presence of a single crystalline structure (that of the host compound) in all samples. Mössbauer spectroscopy confirmed that Fe3+ ions substitute for Sn4+. It was also used to show the disorder induced by the incorporation of iron ions in the structure of the host matrix. Magnetic measurements showed the coexistence of paramagnetism and a weak ferromagnetism. The interaction between singly ionized oxygen vacancies and doping Fe ions is the suggested reason behind the ferromagnetic ordering observed in this research work. The observed ferromagnetism is interpreted in terms of the bound magnetic polaron model and the charge transfer model. The insertion of the transition metal Fe into SnO2 matrix resulted in ferromagnetism at room temperature even at high dopant concentrations. [ABSTRACT FROM AUTHOR]