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Background: Adjuvant administration of hyperthermia (HT) with radiation therapy in the treatment of cancer has been extensively studied in the past five decades. Concurrent use of the two modalities leads to both complementary and synergetic enhancements in tumor management, but presents a practical challenge. Their simultaneous administration using the same implantable thermo‐brachytherapy (TB) seed source has been established theoretically through magnetically mediated heat induction with ferromagnetic materials. Careful consideration, however, showed that regular ferromagnetic alloys lack the required conductivity to generate enough power through eddy current to overcome heat dissipation due to blood perfusion at clinically measured rates. Purpose: We characterized the TB implant that combines a sealed radioactive source with a ferrimagnetic ceramic (ferrite) core, serving as a self‐regulating HT source when placed in an alternating electromagnetic field. To increase the heat production and uniformity of temperature distribution the empty spacers between radioisotope seeds were replaced by hyperthermia‐only (HT‐only) seeds. Methods: The heat generation due to eddy currents circulating in the seed's thin metal shell, surrounding the core, depends drastically on the core permeability. We identified a soft ferrite material (MnZnFe2O4$\rm MnZnFe_2O_4$) as the best candidate for the core, owing to its high permeability, the HT‐range Curie temperature, adjustable through material composition, and a sharp Curie transition, leading to heat self‐regulation, with no invasive thermometry required. The core permeability as a function of temperature was calculated based on measured resistor‐inductor (RL) circuit parameters and material B‐H curves. The thickness of the shell was optimized separately for TB and HT‐only seeds, having slightly different dimensions. Heat generation was calculated using the power versus temperature approximation. Finally, the temperature distribution for a realistic prostate LDR brachytherapy plan was modeled with COMSOL Multiphysics for a set of blood perfusion rates found in the literature. Results: The small size of the investigated ferrite core samples resulted in demagnetization significantly decreasing the relative permeability from its intrinsic value of ∼5000 to about 11 in the range of magnetic field amplitude and frequency values relevant to HT. The power generated by the seed dropped sharply as the shell thickness deviated from the optimal value. The optimized TB and HT‐only seeds generated 45 and 267 mW power, respectively, providing a HT source sufficient for >90% volume coverage even for the highest blood perfusion rates. The toxicity of the surrounding normal tissues was minimal due to the rapid temperature fall off within a few millimeters distance from a seed. Conclusions: The investigated TB and HT‐only seed prototypes were shown to provide sufficient power for the concurrent administration of radiation and HT. In addition to being used as a source for both radiation and heat at the onset of cancer therapy, these implanted seeds would be available for treatment intensification in the setting of salvage brachytherapy for locally radiorecurrent disease, possibly as a sensitizer to systemic therapies or as a modulator of the immune response, without another invasive procedure. Experimentally determined parameters of the ferrite material cores provided in this study establish a mechanistic foundation for future pre‐clinical and clinical validation studies. [ABSTRACT FROM AUTHOR]

Half‐metallic ferromagnets (HMFs) are highly desirable materials for applications in spintronics because of their semiconducting behavior for one spin projection and metallic nature for the other. To operate spintronic devices at room temperature (RT), HMFs should simultaneously have a large saturation magnetization (MS), high magnetic Curie temperature (TC), and a wide half‐metallic gap. However, HMFs that simultaneously fulfill these three criteria are rare. In this work, we report for the first time on the ferrimagnetic double perovskite oxides of Sr2CrHfO6 (SCHO) with a magnetic TC up to 545 K due to the strong Cr3+(↑)Cr4+(↓) antiferromagnetic spin interactions. The combined experimental results confirmed that the SCHO powders crystallized in an orthogonal crystal structure with Pnma symmetry. The SEM images demonstrate that the powders exhibit a spherical morphology with particle sizes between 150 and 250 nm. XPS spectra verified the presence of Sr2+, Cr 3+/Cr4+, and Hf4+/Hfx+ (x < 4) ions in the SCHO powder. Oxygen was present as lattice oxygen and adsorbed oxygen species. At 2 K, the SCHO powder exhibited ferrimagnetic behavior with MS of 0.11 μB/f. u and a magnetic coercive field of 290 Oe. The SCHO ceramics displayed a normal butterfly‐like magnetoresistance‐magnetic field (MR‐H) curve at 2 K due to the intergranular tunneling effect, and the MR (2 K, 7 T) value was −2.05%. The temperature dependence of the resistivity of the SCHO ceramics revealed their semiconducting nature, and the electrical transport data in the temperature range 2−800 K were well fitted by the Mott's variable‐range hopping model, thermal activation model, and small polaron hopping model. Optical measurements demonstrate that the SCHO powders have a direct optical bandgap of 2.25 eV in the visible light window. Having both high TC and a direct optical bandgap (2.25 eV) makes SCHO oxides attractive for use in advanced spintronic devices and solar cells. [ABSTRACT FROM AUTHOR]

Nonreciprocal devices, including optical isolators, phase shifters, and amplifiers, are pivotal for advanced optical systems. However, exploiting natural materials is challenging due to their weak magneto‐optical (MO) effects, requiring substantial thickness to construct effective optical devices. In this study, it is demonstrated that subwavelength metasurfaces supporting bound states in the continuum (BICs) and made of conventional ferrimagnetic material can exhibit strong nonreciprocity in the Faraday configuration and near‐unity magnetic circular dichroism (MCD). These metasurfaces enhance the MO effect by 3–4 orders of magnitude compared to a continuous film of the same material. This significant enhancement is achieved by leveraging Huygens' condition in the metasurface whose structural units support paired electric and magnetic dipole resonances. The multi‐mode temporal coupled mode theory (CMT) is developed for the observed enhancement of the MO effect, and the findings with the full‐wave simulations are confirmed. [ABSTRACT FROM AUTHOR]

A Mn(II) salt and A+CN− under anaerobic conditions react to form 2‐D and 3‐D extended structured compounds of AmMnIIn(CN)m+2n stoichiometry. Here, the creation and characterization of this large family of compounds, for example AMnII3(CN)7, A2MnII3(CN)8, A2MnII5(CN)12, A3MnII5(CN)13, and A2MnII[MnII(CN)6], where A represents alkali and tetraalkylammonium cations, is reviewed. Cs2MnII[MnII(CN)6] has the typical Prussian blue face centered cubic unit cell. However, the other alkali salts are monoclinic or rhombohedral. This is in accord with smaller alkali cation radii creating void space that is minimized by increasing the van der Waals stabilization energy by reducing ∠Mn−N≡C, which, strengthens the magnetic coupling and increases the magnetic ordering temperatures. This is attributed to the non‐rigidity of the framework structure due the significant ionic character associated with the high‐spin MnII sites. For larger tetraalkylammonium cations, the high‐spin Mn sites lack sufficient electrostatic A+⋅⋅⋅NC stabilization and form unexpected 4‐ and 5‐coordinated Mn sites within a flexible, extended framework around the cation; hence, the size, shape, and charge of the cation dictate the unprecedented stoichio‐metry and unpredictable cation adaptive structures. Antiferromagnetic coupling between adjacent MnII sites leads to ferrimagnetic ordering, but in some cases antiferromagnetic coupling of ferrimagnetic layers are compensated and synthetic antiferromagnets are observed. The magnetic ordering temperatures for ferrimagnetic A2MnII[MnII(CN)6] with both octahedral high‐ and low‐spin MnII sites increase with decreasing ∠Mn−N≡C. The crystal structures for all of the extended structured materials were obtained by powder diffraction. [ABSTRACT FROM AUTHOR]

This work concerns the probabilistic analysis of particle‐based materials. More precisely, this work is devoted to the stochastic modeling of the geometric and constitutive microscale parameters associated with particle‐pair interactions of an existing model for particle‐based materials. Such an issue is addressed with a probabilistic methodology that relies on the maximum entropy principle from information theory. After defining and improving the chosen second‐gradient continuum model for particle‐based materials, it is shown that for micro‐homogeneous and micro‐isotropic materials, the involved microscale parameters turn out to be statistically independent. More precisely, the particle‐pair distance between two consecutive particles is a uniformly distributed random variable and the specific micro‐scale stiffness parameters are Gamma‐distributed random variables. A homogeneous and isotropic 2D concrete plate subjected to an axial load is considered for illustration purposes. A stochastic solver based on Monte Carlo numerical simulations and mixed finite element (FE) method are chosen. The FE discretization is applied to the weak formulation of the equivalent continuum model with random mechanical properties. On the contrary, the particle‐pair distance and the micro‐scale stiffness parameters, which are the parameters of the boundary value problem formulated for the equivalent continuum model, are modeled as random variables. Finally, uncertainties propagation is discussed and statistical fluctuations of the macro mechanical response are found to be significant. [ABSTRACT FROM AUTHOR]

This study employs density functional theory to investigate the structural, elastic, electronic, and magnetic properties of FeVScSb and FeVYSb Heusler compounds. FeVScSb exhibits ferromagnetic properties in its stable state, whereas FeVYSb displays ferrimagnetic behavior. The obtained elastic constants (Cij) indicate that FeVScSb and FeVYSb possess mechanical stability and ductility, while also displaying a significant degree of elastic anisotropy. The aggregate magnetic moment of said alloys is determined to be equivalent to 3 μB, in accordance with the Slater–Pauling principle. The investigation of the impact of uniform strain on electronic and magnetic characteristics is conducted. The findings indicate that FeVScSb and FeVYSb exhibit semiconductivity within extensive lattice parameter intervals, ranging from 5.84 to 6.60 Å for FeVScSb and from 6.11 to 6.70 Å for FeVYSb. The Heusler compounds FeVScSb and FeVYSb exhibit half‐metallic behavior within a range of lattice parameters. Specifically, FeVScSb displays this behavior when the lattice parameter varies from 6.61 to 6.72 Å, while FeVYSb exhibits half‐metallicity within the range of 6.71–6.81 Å. Under the influence of strain, the magnetic moment retains a constant value of 3 μB. Therefore, the potential for spintronics is promising. [ABSTRACT FROM AUTHOR]

Exchange bias is a common phenomenon that appears at the interfaces between ferromagnetic and ferrimagnetic materials due to the presence of frozen spins. However, systematic quantification of their intrinsic correlation remains to be a challenge. Herein, the exchange bias induced by frozen spins is assumed as the synergy of an effective static magnetic field and an effective anisotropy, and thus the effect of intrinsic frozen spins at core@shell interfaces of iron@iron‐oxide nanoparticles is estimated. It is confirmed that the shift of the hysteresis loop is 2322 Oe and the coercivity increases from 360 to 1590 Oe. Using micromagnetic simulations, such a hysteresis loop is reconstructed by introducing an effective static magnetic field of 7360 Oe and an effective anisotropy of 45 × 103 J m−3. Therefore, a connection between the intrinsic interfacial frozen spins and the exchange bias effect is established from a mesoscale perspective, mediated by the effective magnetic field and effective anisotropy. The results can provide an understanding of exchange bias effect and promote applications of ferromagnetic/ferrimagnetic heterostructures. [ABSTRACT FROM AUTHOR]

Spin–orbit torques (SOTs) have emerged as an efficient means to electrically control the magnetization in ferromagnetic heterostructures. Lately, increasing attention has been devoted to SOTs in heavy metal (HM)/magnetic insulator (MI) bilayers owing to their tunable magnetic properties and insulating nature. Quantitative characterization of SOTs in HM/MI heterostructures is, thus, vital for the fundamental understanding of charge–spin interrelations and designing novel devices. However, the accurate determination of SOTs in MIs is limited due to low electrical signals and dominant spurious thermoelectric effects caused by Joule heating. Here, a simple method based on harmonic Hall voltage detection and macrospin simulations is reported that accurately quantifies the damping‐like and field‐like SOTs, and thermoelectric contributions separately in MI‐based systems. Experiments on the archetypical Bi‐doped YIG/Pt heterostructure using the developed method yield precise values for the field‐like and damping‐like SOTs, reaching −0.14 and −0.15 mT per 1.7 × 1011 A m−2, respectively. It is further revealed that current‐induced Joule heating changes the spin transparency at the interface, reducing the spin Hall magnetoresistance and damping‐like SOT, simultaneously. These results and the devised methodology can be beneficial for the fundamental understanding of SOTs in MI‐based heterostructures and device designs where accurate SOTs knowledge is necessary. [ABSTRACT FROM AUTHOR]

Heusler compounds have generated significant interest in spintronics due to their unique features. The structural stability, electronic structure, magnetic, and elastic properties of Heusler alloys VXRh2 (X = Sn, Ge, and Si) are investigated using first‐principles calculations of density functional theory in the Quantum Espresso code. The alloys exhibit three magnetic states (nonmagnetic, ferromagnetic, and ferrimagnetic) and several structural phases (face centered cubic (FCC) and tetragonal). It is found that pressures below 0 GPa produce the FCC phase, while greater pressures produce two tetragonal phases. VSnRh2 is a ferromagnetic metal, while VSiRh2 and VGeRh2 exhibit excellent half‐metallic ferromagnetism. The equilibrium lattice constants of VSiRh2 and VGeRh2 are stable against changes, making these Heusler alloys ideal for spintronic devices. Elastic constant computations show that compounds are mechanically stable. [ABSTRACT FROM AUTHOR]

The magnetic and magnetocaloric properties of the nano‐graphene monolayer structure consisting of mixed spins S = 3/2 and σ = 2 are studied by using Monte Carlo simulations. The ground‐state phase diagrams corresponding to several physical parameters are first discussed. The influence of the number of lattice sites on the total and partial magnetizations and the magnetic susceptibilities has been investigated. The critical temperature is deduced. The effect of exchange interaction, external magnetic, and crystal field on total magnetizations is studied. Magnetic hysteresis cycles are obtained. Specific heat change and magnetic entropy changes are inferred for several magnetic fields. Finally, the relative cooling power is determined. [ABSTRACT FROM AUTHOR]

Nontrivial chiral spin textures with nanometric sizes and novel characteristics (e.g., magnetic skyrmions) are promising for encoding information bits in future energy‐efficient and high‐density spintronic devices. Because of antiferromagnetic exchange coupling, skyrmions in ferrimagnetic materials exhibit many advantages in terms of size and efficient manipulation, which allow them to overcome the limitations of ferromagnetic skyrmions. Despite recent progress, ferrimagnetic skyrmions have been observed only in few films in the presence of external fields, while those in ferrimagnetic bulks remain elusive. This study reports on spontaneously generated zero‐field ground‐state magnetic skyrmions and their subsequent transformation into traditional magnetic bubbles via intermediate states of (bi‐)target bubbles during a magnetic anisotropy change in the rare‐earth ferrimagnetic crystal DyFe11Ti. Spontaneous reversible topological transformation driven by a temperature‐induced spin reorientation transition is directly distinguished using Lorentz transmission electron microscopy. The spontaneous generation of magnetic skyrmions and successive topological transformations in ferrimagnetic DyFe11Ti are expected to advance the design of topological spin textures with versatile properties and potential applications in rare‐earth magnets. [ABSTRACT FROM AUTHOR]

Magnetic tunnel junctions (MTJs) exhibit a great profusion of unique functional properties, such as nonvolatility, scalability, high endurance, and low power consumption. For this reason, they have been widely investigated in spin-based logic and memory devices. Compared with conventional in-plane MTJs, perpendicular MTJs (pMTJs) enable lower critical switching current and higher integration density. So far, CoFeB/MgO structures with interface-induced perpendicular magnetic anisotropy (PMA) are the most common ferromagnetic (FM) electrodes in pMTJs, whereas their relatively weak interfacial PMA restricts further development of device nodes. In the past decade, perpendicularly magnetized MnxGa binary alloys, including FM L10-MnGa and ferrimagnetic D022-Mn3Ga, have drawn intense attention for serving as a promising magnetic electrode in various MTJ stacking structures because of their large PMA, high spin polarization, and small magnetic damping constant. From an application perspective, MTJs with ultrathin MnxGa electrode show merits in developing high-density magnetic memory, high-frequency spin-torque oscillators, and tunneling magnetoresistance effect-based high-field sensors. Herein, the aim is to provide a comprehensive review of recent progress in perpendicularly magnetized MnxGa-based MTJs. The conclusions and future prospects are also given to inspire more in-depth research and advance the practical applications. [ABSTRACT FROM AUTHOR]

Ferrimagnets are the magnetic materials with the fastest current-induced dynamics reported so far. Among them, rare-earth transition-metal (RE-TM) alloys offer a fertile playground for studying the behavior of multi-sublattice systems with tunable composition and magnetic interactions. This review provides a survey of the magnetic dynamics excited by current-induced spinorbit torques (SOTs) in RE-TM ferrimagnets coupled to heavy-metal layers. It summarizes the magnetic properties of RE-TM alloys and discusses how interfacial SOTs result in efficient magnetization switching and fast domainwall motion close to the magnetization and angular momentum compensation points. Recent work shows that the switching is a multiphase process affected by significant stochastic fluctuations. However, strong SOTs results in fast and deterministic sub-ns switching with minimal energy dissipation. In addition, the RE and TM magnetizations can respond asynchronously to SOTs during the reversal. This asynchronous dynamics pinpoints the different strength of the SOTs acting on the two sublattices and challenges the usual assumption of rigid inter-sublattice antiferromagnetic coupling. Overall, the ability to tailor the timescale and reversal mode of RE-TM alloys allows for optimizing the speed of ferrimagnetic spintronic devices and provides insight into the current-induced transfer of angular momentum in systems with synergistic ferromagnetic and antiferromagnetic interactions. [ABSTRACT FROM AUTHOR]

By employing a melt‐sintering method, we prepared a new type of ferrimagnetic glass–ceramic foam (FGCF) using ferrimagnetic glass–ceramic and foaming agent SrCO3. The ferrimagnetic glass–ceramics were fabricated based on pyrite slag by a melt‐quenching method. The effects of foaming agent content, sintering temperature and time on microstructure, magnetic properties, microwave absorption performance, compressive strength, and thermal conductivity of the as‐obtained FGCF were analyzed. This foaming process at 1100°C for 40 min with 3‐wt% SrCO3 provided an FGCF with a bulk density of.693 g/cm3, a porosity of 63.60%, a specific saturation magnetic moment of 5.2 A m2/kg, a compressive strength of 2.61 MPa, a thermal conductivity of.241 W/(m K), and the calculated reflection loss of −12.1 dB for a layer thickness of 9 mm. [ABSTRACT FROM AUTHOR]

Using exact diagonalization, the density matrix renormalization group approach and the quantum Monte‐Carlo method, we studied the peculiarities of the magnetization profiles and the possibility of spin switching for the Heisenberg spin models of low‐dimensional composite magnets formed by graphene nanoclusters and complex transition‐metal compounds. For these models, we found the presence of intermediate plateaus in the low‐temperature magnetization profiles, which is in agreement with known experimental and theoretical studies of the magnetization profiles of nanostructured magnets with the ferrimagnetic spin ordering in the ground state. For spin‐chain model of composite magnets proposed, we also found a possibility of single and double spin switching with the macroscopic jump of the ground state spin results from frustrated spin interactions. [ABSTRACT FROM AUTHOR]

Cation ordering in solids is important for controlling physical properties and leads to ilmenite (FeTiO3) and LiNbO3 type derivatives of the corundum structure, with ferroelectricity resulting from breaking of inversion symmetry in the latter. However, a hypothetical third ABO3 derivative with R32 symmetry has never been observed. Here we show that Co2InSbO6 recovered from high pressure has a new, ordered‐R32 A2BCO6 variant of the corundum structure. Co2InSbO6 is also remarkable for showing two cation redistributions, to (Co0.5In0.5)2CoSbO6 and then Co2InSbO6 variants of the ordered‐LiNbO3 A2BCO6 structure on heating. The cation distributions change magnetic properties as the final ordered‐LiNbO3 product has a sharp ferrimagnetic transition unlike the initial ordered‐R32 phase. Future syntheses of metastable corundum derivatives at pressure are likely to reveal other cation‐redistribution pathways, and may enable ABO3 materials with the R32 structure to be discovered. [ABSTRACT FROM AUTHOR]

Cation ordering in solids is important for controlling physical properties and leads to ilmenite (FeTiO3) and LiNbO3 type derivatives of the corundum structure, with ferroelectricity resulting from breaking of inversion symmetry in the latter. However, a hypothetical third ABO3 derivative with R32 symmetry has never been observed. Here we show that Co2InSbO6 recovered from high pressure has a new, ordered‐R32 A2BCO6 variant of the corundum structure. Co2InSbO6 is also remarkable for showing two cation redistributions, to (Co0.5In0.5)2CoSbO6 and then Co2InSbO6 variants of the ordered‐LiNbO3 A2BCO6 structure on heating. The cation distributions change magnetic properties as the final ordered‐LiNbO3 product has a sharp ferrimagnetic transition unlike the initial ordered‐R32 phase. Future syntheses of metastable corundum derivatives at pressure are likely to reveal other cation‐redistribution pathways, and may enable ABO3 materials with the R32 structure to be discovered. [ABSTRACT FROM AUTHOR]

The discovery of ultrafast helicity‐independent all‐optical switching (HI‐AOS), as well as picosecond all‐electrical switching of a ferrimagnet, has inspired the ultrafast spintronics community to explore ultrafast switching of a ferromagnet to achieve practical ultrafast storage and memory devices. Two explored mechanisms of HI‐AOS of a ferromagnet in ferromagnet‐ferrimagnet heterostructure are: a) exploiting the indirect exchange coupling with and b) injection of non‐local spin current originated from a switching ferrimagnet. In this manuscript, exchange mediated HI‐AOS of a Ruderman–Kittel–Kasuya–Yosida (RKKY) exchange coupled "[Co/Pt]‐multilayers/Pt spacer/CoGd" heterostructure is demonstrated. The authors have measured layer‐resolved static magnetic properties, single‐shot HI‐AOS, and magnetization dynamics of the ferromagnetic Co/Pt multilayers (MLs), that are ferromagnetically or antiferromagnetically coupled with ferrimagnetic CoGd layers. Time‐resolved magnetization dynamics reveal a 3.5 ps switching time of the Co/Pt MLs, which is the fastest switching of a ferromagnet reported to date. Employing an extended microscopic three‐temperature model, the temporal dynamics of the exchange coupled ferromagnet–ferrimagnet heterostructure are simulated, qualitatively and quantitatively explaining the experimental switching phenomena. This work experimentally as well as theoretically establishes the mechanism of exchange mediated all‐optical switching of ferromagnet‐ferrimagnet heterostructures, which can be integrated with a magnetic tunnel junction for efficient reading after ultrafast energy‐efficient switching. [ABSTRACT FROM AUTHOR]

Magnetic and flexible nanocomposites of polyamide 6 (PA6)/styrene‐(ethylene‐butylene)‐styrene grafted with maleic anhydride (SEBS‐MA) were prepared using Ni‐Zn ferrite synthesized by combustion reaction. Thermal treatment was applied to the Ni‐Zn ferrite to form a more crystalline phase. The nanocomposites were processed in an internal mixer and later injection molded. The materials were characterized by torque rheometry, X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Izod impact strength, tensile strength, magnetic measurements, differential scanning calorimetry (DSC), thermogravimetry (TG), heat deflection temperature (HDT), and scanning electron microscopy (SEM). Ferrite calcination led to a higher degree of crystallinity and nanocomposites with a higher number of crystalline peaks. This favored a higher saturation magnetization. The magnetic hysteresis curves of the nanocomposites indicated a ferrimagnetic behavior. The impact strength and elongation at break increased significantly compared to neat PA6, suggesting the formation of flexible and magnetic nanocomposites. This behavior was ascribed to a chemical reaction between the terminal amine groups of PA6 and the maleic anhydride of SEBS‐MA, confirmed by FTIR and torque rheometry. Neat PA6 and the nanocomposites showed similar thermogravimetric, HDT, melting temperature, and crystallization properties. SEM results showed that the dispersed ferrite tends to form agglomerates, especially if calcined. In general, the addition of the non‐calcined Ni‐Zn ferrite to the PA6 matrix improved the mechanical properties. Conversely, the calcination of ferrite tended to improve the magnetic behavior of the nanocomposites. [ABSTRACT FROM AUTHOR]

Ferrimagnetic thin films are attractive for low‐power spintronic applications because of their low magnetization, small angular momentum, and fast spin dynamics. Spin orbit torques (SOT) can be applied with proximal heavy metals that also generate interfacial Dzyaloshinskii–Moriya interactions (DMI), which can stabilize ultrasmall skyrmions and enable fast domain wall motion. Here, the properties of a ferrimagnetic CoGd alloy between two heavy metals to increase the SOT efficiency, while maintaining a significant DMI is studied. SOT switching for various capping layers and alloy compositions shows that Pt/CoGd/(W or Ta) films enable more energy‐efficient SOT magnetization switching than Pt/CoGd/Ir. Spin‐torque ferromagnetic resonance confirms that Pt/CoGd/W has the highest spin‐Hall angle of 16.5%, hence SOT efficiency, larger than Pt/CoGd/(Ta or Ir). Density functional theory calculations indicate that CoGd films capped by W or Ta have the largest DMI energy, 0.38 and 0.32 mJ m−2, respectively. These results show that Pt/CoGd/W is a very promising ferrimagnetic structure to achieve small skyrmions and to move them efficiently with current. [ABSTRACT FROM AUTHOR]

Magnetic 2D materials have emerged as a great interest in spintronics due to atomic thickness scaling, low energy switching, and ease in the manipulation of spins. This report demonstrates a facile, bottom‐up, chemical vapor deposition approach for non‐van der Waals (non‐vdWs), 2D chromium (III) sulfide (Cr2S3) with c‐axis orientation, out‐of‐plane magnetic anisotropy (easy axis), and ferrimagnetic ordering. Importantly, the anisotropic magnetic saturation and resistivity of 10.23 mΩ cm reveal a narrow bandgap ferrimagnetism in Cr2S3 (∆EActivation ≈ 22 meV and Eg ≈ 40 meV). The prototype lateral spin‐channel Al/Cr2S3/Al devices exhibit a negative magnetoresistance of ≈25% and ≈15% at 100 K (below Néel temperature) for few‐layer (≈8 nm) and thin‐film (≈50 nm) device structures, respectively, owing to itinerant ferrimagnetism of Cr2S3. The magnetic field‐induced spin polaron formations are quite resilient and enhance the field‐dependent carrier conduction, making it greatly useful for negative magnetoresistance operation. These prototype Al/Cr2S3/Al structures have demonstrated a low power (≈2 µW for 8 µm channel at 10 µA current) operation with a negative field‐dependent resistance coefficient (rM) of ≈−5 × 10−4 Oe−1. The computed rM magnitude is tenfold higher than the bulk Cr2S3. This study identifies the potential of non‐vdW Cr2S3 toward new and robust 2D‐based spintronic applications. [ABSTRACT FROM AUTHOR]

Volume‐dependent magnetic susceptibility (κ) is commonly used for paleoenvironmental reconstructions in both terrestrial and marine sedimentary environments where it reflects a mixed signal between primary deposition and secondary diagenesis. In the marine environment, κ is strongly influenced by the abundance of ferrimagnetic minerals regulated by sediment transport processes. Post‐depositional alteration by H2S, however, can dissolve titanomagnetite, releasing reactive Fe that promotes pyritization and subsequently decreases κ. Here, we provide a new approach for isolating the detrital signal in κ and identifying intervals of diagenetic alteration of κ driven by organoclastic sulfate reduction (OSR) and the anaerobic oxidation of methane (AOM) in methane‐bearing marine sediments offshore India. Using the correlation of a heavy mineral proxy from X‐ray fluorescence data (Zr/Rb) and κ in unaltered sediments, we predict the primary detrital κ signal and identify intervals of decreased κ, which correspond to increased total sulfur content. Our approach is a rapid, high‐resolution method that can identify overprinted κ resulting from pyritization of titanomagnetite due to H2S production in marine sediments. In addition, total organic carbon, total sulfur, and authigenic carbonate δ13C measurements indicate that both OSR and AOM can drive the observed κ loss, but AOM drives the greatest decreases in κ. Overall, our approach can enhance paleoenvironmental reconstructions and provide insight into paleo‐positions of the sulfate‐methane transition zone, past enhancements of OSR or paleo‐methane seepage, and the role of detrital iron oxide minerals on the marine sediment sulfur sink, with consequences influencing the development of chemosynthetic biological communities at methane seeps. Plain Language Summary: In continental margin environments, variation in the magnetic susceptibility (κ) of marine sediments is influenced primarily by the delivery of detrital magnetic minerals from continental erosion and secondarily by diagenetically driven dissolution and/or growth of new magnetic minerals within the sediments. Bulk sediment measurements of κ often record a mixed signal from these processes, making it difficult to distinguish the original depositional detrital signal from in situ diagenetic effects. Here, we provide a new approach for isolating the detrital signal in κ and identifying intervals of diagenetic alteration in methane‐bearing marine sediments in the offshore Krishna‐Godavari basin, eastern peninsular India. We utilize measurements of κ, magnetic properties, a heavy mineral proxy (Zr/Rb from X‐ray fluorescence), total organic carbon (TOC) and total sulfur (TS), and authigenic carbonate carbon isotopes to determine which portions of the records reflect primary deposition and which reflect diagenesis associated with abundant TOC or abundant methane. Overall, by decoupling the mixed signal of κ, our approach can allow for improved interpretation of marine sediment sequences globally and has implications for reconstructing the role of detrital magnetic minerals on the marine sediment sulfur cycle and the development of chemosynthetic biological communities at methane seeps. Key Points: Zr/Rb as a heavy mineral proxy tracks well with magnetic susceptibility (κ) in stratigraphy unaltered by diagenesisPyritization driven by both organoclastic sulfate reduction and the anaerobic oxidation of methane results in a relative loss of (κ)At methane seeps pyritization is regulated by detrital Fe‐oxides, limiting or enhancing the role of pyrite as a global sulfur sink [ABSTRACT FROM AUTHOR]

The evolution of chiral spin structures is studied in ferrimagnetic Ta/Ir/Fe/GdFeCo/Pt multilayers as a function of temperature using scanning electron microscopy with polarization analysis (SEMPA). The GdFeCo ferrimagnet exhibits pure right‐handed Néel‐type domain wall (DW) spin textures over a large temperature range. This indicates the presence of a negative Dzyaloshinskii–Moriya interaction that can originate from both the top Fe/Pt and the Co/Pt interfaces. From measurements of the DW width, as well as complementary magnetic characterization, the exchange stiffness as a function of temperature is ascertained. The exchange stiffness is surprisingly more or less constant, which is explained by theoretical predictions. Beyond single skyrmions, it is identified by direct imaging a pure Néel‐type skyrmionium, which due to the expected vanishing skyrmion Hall angle, is a promising topological spin structure to enable applications by next generation of spintronic devices. [ABSTRACT FROM AUTHOR]

The dynamic response of magnetically ordered materials to an ultrashort external stimulus depends on microscopic parameters, such as magnetic moment, exchange, and spin–orbit interactions. Whereas it is well established that, in multicomponent magnetic alloys and compounds, the speed of demagnetization and spin switching processes has an element‐specific character, the magnetization damping was assumed to be a universal parameter for all constituent magnetic elements irrespective of their different spin–orbit couplings and electronic structure. Herein, experimental and theoretical evidence for an element‐specific magnetic damping parameter is provided by investigating the ultrafast magnetization response of a high‐anisotropy ferrimagnetic DyCo5 alloy to femtosecond laser excitation. Strikingly different demagnetization and remagnetization dynamics of Dy and Co magnetic moments is revealed by employing femtosecond laser pump–X‐ray magnetic circular dichroism probe measurements combined with atomistic spin dynamics (ASD) simulations using ab initio calculated parameters. These observations, fully corroborated by the ASD simulations, are linked to the element‐specific spin–orbit coupling strengths of Dy and Co, which are incorporated in the phenomenological magnetization damping parameters. These findings can be used as a recipe for tuning the speed and magnitude of laser‐driven magnetic processes and consequently allow control over various dynamic functionalities in multicomponent magnetic materials. [ABSTRACT FROM AUTHOR]

Anisotropy of magnetic susceptibility (AMS) and anisotropy of magnetic remanence (AARM and AIRM) are efficient and versatile techniques to indirectly determine rock fabrics. Yet, deciphering the source of a magnetic fabric remains a crucial and challenging step, notably in the presence of ferrimagnetic phases. Here we use X‐ray micro‐computed tomography to directly compare mineral shape‐preferred orientation and spatial distribution fabrics to AMS, AARM and AIRM fabrics from five hypabyssal trachyandesite samples. Magnetite grains in the trachyandesite are euhedral with a mean aspect ratio of 1.44 (0.24 s.d., long/short axis), and >50% of the magnetite grains occur in clusters, and they are therefore prone to interact magnetically. Amphibole grains are prolate with magnetite in breakdown rims. We identified three components of the petrofabric that influence the AMS of the analyzed samples: The magnetite and the amphibole shape fabrics and the magnetite distribution anisotropy. Depending on their relative strength, orientation and shape, these three components interfere either constructively or destructively to produce the AMS fabric. If the three components are coaxial, the result is a relatively strongly anisotropic AMS fabric (P' = 1.079). If shape fabrics and/or magnetite distribution anisotropy are non‐coaxial, the resulting AMS is weakly anisotropic (P' = 1.012). This study thus reports quantitative petrofabric data that show the effect of magnetite distribution anisotropy on magnetic fabrics in igneous rocks, which has so far only been predicted by experimental and theoretical models. Our results have first‐order implications for the interpretation of petrofabrics using magnetic methods. Key Points: Trachyandesite analyzed with X‐ray microtomography for comparison between magnetic fabrics and the components of the petrofabricMagnetite and amphibole shape fabrics and magnetite distribution constructively or destructively interfere to produce magnetic fabricsDistribution anisotropy significantly affects the anisotropy of magnetic susceptibility and anisotropy of remanent magnetization [ABSTRACT FROM AUTHOR]

Herein, a modified solid state synthesis of Na0.67Mn0.5Fe0.5O2 and the results of a detailed investigation of the structural and magnetic properties via Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), X‐ray absorption spectroscopy (XAS), scanning electron microscopy (SEM), and energy dispersive X‐ray (EDX) analysis are reported. The magnetic properties of Na0.67Mn0.5Fe0.5O2 do not fit the Curie–Weiss law and a model regarding the spin configuration of the Mn and Fe ions and a possible ferrimagnetic order is suggested. Electrochemical measurements and ex situ structural analysis of the cathode material confirm the reversible structural transitions for the cells charged up to 4.0 V. Environmental temperature–dependent electrochemical measurements reveal a strong temperature dependence of both, the initial capacity and the capacity retention. Ex situ SEM, FTIR, and XRD studies on the battery membrane verify the formation of a Na2CO3 phase on the membrane, which blocks the Na ion diffusion through membrane pores and is responsible for the capacity fade for this compound. [ABSTRACT FROM AUTHOR]

Ferrimagnetic greigite (Fe3S4) is widespread in the sedimentary environment. Despite abundant reports of greigite occurrence in marine and lacustrine deposits, its formation mechanisms in deltaic deposits remain poorly studied. Here we investigate greigite in Holocene Yangtze River Delta deposits using granulometric, magnetic, and geochemical methods. The studied cores consist of tidal river, estuary, shallow marine, and delta facies in ascending order. The greigite‐bearing layers are found predominantly in the accreting tidal flat facies during the transgression stage and secondarily in the shallow marine facies during the regression stage of the delta's Holocene development. These sedimentary intervals have a higher total sulfur (TS) content and TS to total organic carbon ratios (TS/TOC) suggesting the accumulation of iron sulfides, including greigite, under reducing estuarine and shallow marine conditions. The greigite‐bearing layers in the tidal flat facies have lower Sr/Ba ratios, in comparison to the shallow marine facies, indicating a lower salinity environment. Supported by the dating results, it is suggested that the higher sedimentation rate of the tidal flat facies, caused by rapid sea‐level rise during the early Holocene, favors the formation and preservation of greigite. Our results indicate that the magnetic detection of greigite provides a simple and useful tool for inferring salinity and sedimentation rate changes, and hence better an understanding of the heterogeneity of depositional processes in Holocene delta environments. Plain Language Summary: Greigite (Fe3S4), an early or late diagenetic magnetic mineral, is an iron sulfide commonly produced during the carbon‐iron‐sulfur (C‐Fe‐S) cycle in aquatic environments. Its occurrence is generally found to be linked to water salinity change, which can be used to infer changes in past environmental conditions such as drought and flood events. So far, studies on greigite have focused on marine and lacustrine deposits. Its formation mechanisms in delta environments remain poorly known, where fresh and marine water mixing results in intensive spatial and temporal salinity change. In this study, environmental magnetic measurement and salinity indictors for example, the ratio of strontium to barium (Sr/Ba), the ratio of total sulfur to total organic carbon (TS/TOC) and TS concentration are combined to reveal greigite occurrence and its formation conditions. Our results show that higher sedimentation rates and marked salinity change associated with rapid sea level rise in the early Holocene is favorable for greigite generation and preservation. We find that magnetic detection of greigite can provide valuable information regarding spatial/temporal variabilities in fresh‐marine water mixing and depositional processes in deltaic environment. Key Points: We identify greigite at the boundary of sedimentary facies with marked salinity change in the Yangtze River DeltaGreigite‐bearing layers occurs predominantly in accreting tidal flat facies with a higher sedimentation rateMagnetic identification of gregite can assist stratigraphic differentiation in delta deposits [ABSTRACT FROM AUTHOR]

The antiperovskite Co4N is studied using density functional theory (DFT) calculations and Monte Carlo (MC) simulation within the framework of the Ising model. The structural, density of states (DOS), and band structure calculations show that Co4N is a ferromagnetic material having a higher magnetic moment, a large spin polarization ratio, and exhibits a metallic behavior. The investigated elastic constants, phonon dispersion, and phonon DOS show that the Co4N compound is mechanically and dynamically stable. It is also found that the Co4N is ductile from the Poisson's ratio, Pugh's ratio, and Cauchy pressure. The thermodynamic parameters like heat capacity, Debye and melting temperature are calculated. The magnetization, magnetic susceptibility, and the Curie temperature of magnetic transition are estimated using MC simulations based on the Ising model. The obtained value of TC is in good agreement with available theoretical work. [ABSTRACT FROM AUTHOR]

The rheological behavior of pure molybdenum at a temperature range of 1150–1300 °C at an interval of 50 °C with strain rates ranging from 0.01 to 10 s−1 is studied by means of an isothermal compression experiment. The obtained true stress–strain curves reflect the strong dependence of the flow stress on the deformation temperatures and strain rates. To accurately describe the rheological behavior, a classic Arrhenius‐type equation is utilized for verification, which has been developed to consider the strain compensation. The results show that the modified constitutive equation has the ability to accurately predict performance. Meanwhile, processing maps of pure molybdenum under strains of 0.3, 0.4, 0.5, and 0.6 are also constructed and the deformation safety in different domains is discussed in conjunction with the metallographic structure. The deformation conditions at a temperature range of 1250–1300 °C and a strain rate of 0.01–0.23 s−1 are the optimal hot working parameters under a strain of 0.6, which creates a foundation for the effective hot forming of molybdenum. [ABSTRACT FROM AUTHOR]

The reactions of MnII(O2CCH3)2 with NEt3Me+CN− and NEt2Me2+CN− form (NEt3Me)2MnII5(CN)12 (1) and (NEt2Me2)2MnII5(CN)12 (2), respectively. Structure model‐building and Rietveld refinement of high‐resolution synchrotron powder diffraction data revealed a cubic [a=24.0093 Å (1), 23.8804 Å (2)] 3D extended structural motif with adjacent tetrahedral and octahedral MnII sites in a 3:2 ratio. Each tetrahedral MnII site is surrounded by four low‐spin octahedral MnII sites, and each octahedral MnII site is surrounded by six high‐spin tetrahedral MnII sites; adjacent sites are antiferromagnetically coupled in 3D. Compensation does not occur, and magnetic ordering as a ferrimagnet is observed at Tc=13 K for 2 based on the temperature at which remnant magnetization, Mr(T)→0. The hysteresis has an unusual constricted shape with inflection points around 50 and 1.2 kOe with a 5 K coercivity of 16 Oe and remnant magnetization, Mr, of 2050 emuOe mol−1. The unusual structure and stoichiometry are attributed to the very ionic nature of the high‐spin N‐bonded MnII ion, which enables the maximization of the attractive van der Waals interactions through minimization of void space via a reduced ∠ MnNC. This results in an additional example of the AxMnIIy(CN)x+2y (x=0, y=1; x=1, y=3; x=2, y=1; x=2, y=2; x=2, y=3; x=3, y=5; and x=4, y=1) family of compounds possessing an unprecedented stoichiometry and lattice motif that are cation adaptive structured materials. [ABSTRACT FROM AUTHOR]

We document magnetic mineral diagenesis with high‐resolution magnetic susceptibility, hysteresis, isothermal remanent magnetization, and other rock magnetic measurements through a shallow sulfate‐methane transition (SMT) at Perseverance Drift—a high‐accumulation rate Holocene biosiliceous Antarctic marine sediment deposit. The structure of the SMT is defined with porewater measurements from the same core, allowing direct comparison. Dissolution of the detrital (titano)magnetite assemblage, with preferential dissolution of stochiometric magnetite, occurs in the upper SMT. Higher coercivity magnetic minerals dissolve more slowly, continuing to dissolve through the entire SMT and could be a source of ferric iron for microbial respiration following exhaustion of porewater sulfate, as suggested by accumulation of porewater ferrous iron below the SMT. Superparamagnetic ferrimagnetic mineral enrichment/depletion occurs in three phases through the SMT and is coupled tightly to the availability of dissolved ferrous iron relative to dissolved sulfide. High concentrations of authigenic remanence‐bearing iron sulfides, including greigite and hexagonal 3C pyrrhotite, which can be detected using remanence parameters but not in‐field concentration dependent parameters, accumulate in a transient horizon at the base of the SMT during this early diagenesis, where sulfide is present but limited relative to dissolved ferrous iron. Formation of this remanence‐bearing iron sulfide horizon is likely facilitated by continued iron reduction through the SMT. Nonsteady state perturbations that shift the porewater profile, such as changes in carbon flux or sedimentation rate, can lead to preservation of these transient horizons, much like well documented preservation of manganese oxide layers in marine sediments following similar shifts to porewater profiles. Key Points: Magnetic mineral diagenesis is studied in Antarctic sediments using high‐resolution porewater and rock magnetic dataMagnetic mineral dissolution and authigenesis is tightly coupled to dissolved sulfide and ferrous iron concentrationsRemanence‐bearing iron sulfides form below the sulfate‐methane transition and can be preserved following nonsteady state diagenesis [ABSTRACT FROM AUTHOR]

Magnonics—an emerging field of physics—is based on the collective excitations of ordered spins called spin waves. These low‐energy excitations carry pure spin currents, paving the way for future technological devices working at low energies and on ultrafast timescales. The traditional ab‐initio approach to predict these spin‐wave energies is based on linear‐response time‐dependent density functional theory (LR‐TDDFT) in the momentum and frequency regime. Herein, the simulation of magnon dynamics using real‐time time‐dependent density functional theory is demonstrated, thus extending the domain of ab‐initio magnonic studies. Unlike LR‐TDDFT, this enables us to observe atom‐resolved dynamics of individual magnon modes and, using a supercell approach, the dynamics of several magnon modes can be observed simultaneously. The energies of these magnon modes are concurrent with those found using LR‐TDDFT. Next, the complex dynamics of the superposition of magnon modes is studied, before finally studying the element‐resolved modes in multisublattice magnetic systems. [ABSTRACT FROM AUTHOR]

Given the consensus that pressure improves cation ordering in most of known materials, a discovery of pressure‐induced disordering could require recognition of an order–disorder transition in solid‐state physics/chemistry and geophysics. Double perovskites Y2CoIrO6 and Y2CoRuO6 polymorphs synthesized at 0, 6, and 15 GPa show B‐site ordering, partial ordering, and disordering, respectively, accompanied by lattice compression and crystal structure alteration from monoclinic to orthorhombic symmetry. Correspondingly, the long‐range ferrimagnetic ordering in the B‐site ordered samples are gradually overwhelmed by B‐site disorder. Theoretical calculations suggest that unusual unit‐cell compressions under external pressures unexpectedly stabilize the disordered phases of Y2CoIrO6 and Y2CoRuO6. [ABSTRACT FROM AUTHOR]

Spin Hall effect (SHE)‐induced reversal of perpendicular magnetization has attracted significant interest, due to its potential for low‐power memory and logic devices. However, the switching requires an assisted in‐plane magnetic field, which hampers its practical applications. Here, a new approach for external‐field‐free spin Hall switching of a perpendicular nanomagnet is introduced. This approach utilizes a local dipolar field arising from an in‐plane biasing layer to assist the switching. Robust switching of a 285 × 95 nm2 perpendicular CoFeB nanomagnet is demonstrated in the absence of any external magnetic field. Micromagnetic simulation is performed to illustrate the magnetic dynamics of the switching process. Large in‐plane compensation field of 135 Oe is obtained in the composite nanodevices, reflecting a strong symmetry‐breaking behavior. Compared with other proposed methods for external‐field‐free spin Hall switching, the dipole‐coupled composite structure is compatible with a wide range of spin Hall systems and perpendicular magnetic tunnel junctions, paving a way towards practical spin–orbit torque‐based memory and logic applications. [ABSTRACT FROM AUTHOR]

The seminal discovery in 1981 of bimetallic ferrimagnetic chains, based on the synthetic use of the concept "complex as ligand", can be considered as a significant step on the way from molecules to more and more complex materials. We describe the chemistry, the structures, the magnetic properties of these 1D materials, together with the new theoretical models created to understand them. We then give an overview of some original creative ideas, which have irrigated the synthetic chemistry of brand‐new molecular materials, room temperature magnets, photomagnetic and chiral magnets or functional surfaces. The review emphasizes that the celebrated individual "wins" are indeed the fruit, along the years, of the constructive multidisciplinary collaboration of many scientists, theoreticians and experimentalists, chemists and physicists. Difficulties, dead‐end hypotheses, mistakes which represent a significant exciting part of any scientific endeavour, are not put under the rug. [ABSTRACT FROM AUTHOR]

The cobalt(II) in [Co(NCS)2(4‐methoxypyridine)2]n are linked by pairs of thiocyanate anions into linear chains. In contrast to a previous structure determination, two crystallographically independent cobalt(II) centers have been found to be present. In the antiferromagnetic state, below the critical temperature (Tc=3.94 K) and critical field (Hc=290 Oe), slow relaxations of the ferromagnetic chains are observed. They originate mainly from defects in the magnetic structure, which has been elucidated by micromagnetic Monte Carlo simulations and ac measurements using pristine and defect samples. The energy barriers of the relaxations are Δτ1=44.9(5) K and Δτ2=26.0(7) K for long and short spin chains, respectively. The spin excitation energy, measured by using frequency‐domain EPR spectroscopy, is 19.1 cm−1 and shifts 0.1 cm−1 due to the magnetic ordering. Ab initio calculations revealed easy‐axis anisotropy for both CoII centers, and also an exchange anisotropy Jxx/Jzz of 0.21. The XXZ anisotropic Heisenberg model (solved by using the density renormalization matrix group technique) was used to reconcile the specific heat, susceptibility, and EPR data. [ABSTRACT FROM AUTHOR]

NiFe2O4/ZrO2 composite with varied compositional ratios was formed through solution‐based sol‐gel synthetic route. The ability to retain NiFe2O4/ZrO2 composite structures was dependent on the concomitant effect of temperature gradient and precursor concentration. The crystallization of t‐ZrO2 alongside the incidence of NiFe2O4 and NiO was evident at 900°C. However, the gradual elimination of NiO and simultaneous enhancement in NiFe2O4 content is inevitable at 1300°C. Morphological analysis of the composite revealed discrete distribution of ZrO2 and NiFe2O4 grains and also portrays the dense and pore‐free microstructures. Despite the presence of varied amount of NiFe2O4 in the composites, the resultant mechanical properties displayed relatively better values and exhibited good similarities with the hard tissue. As expected, a gradual increment in the ferrimagnetic properties as a function of enhanced NiFe2O4 content was induced. Further, in vitro analysis delivered good biocompatibility features of the investigated NiFe2O4/ZrO2 composite. [ABSTRACT FROM AUTHOR]

W‐type SrFe22+Fe163+O27 ferrite is a member of the hexagonal ferrite family and a potential permanent magnet material. However, its synthesis conditions are not fully understood yet. Samples were sintered either at 1400°C in air and quenched, or at 1300°C at reduced oxygen partial pressure. The precise stability conditions of this W‐type ferrite were investigated in the temperature range of 1200°C‐1400°C using thermogravimetry, XRD, and electron microscopy. At 1300°C, the ferrite is stable at oxygen partial pressures of -3.1≤logpO2≤-1.6. At more oxidizing conditions, the ferrite decomposes into M‐type ferrite and hematite, while at more reducing atmospheres Sr4Fe6O13 and magnetite are formed. The nonstoichiometry δ of SrFe18−δO27 was derived from thermal analysis data at 1300°C as function of oxygen partial pressure and was found to be mainly due to cation vacancies. Magnetization measurements show that this W‐type ferrite exhibits Ms = 103 emu/g at T = 4 K, which agrees well with a ferrimagnetic spin arrangement according to Gorter's model. As alternative, Zn‐substituted W‐ferrite was found to be stable in air at 1200°C with a large Ms = 123 emu/g at 4 K. [ABSTRACT FROM AUTHOR]

State‐of‐the‐art paleoclimate research strongly depends on the availability of time‐equivalent markers as chronological control to disentangle interrelationships in the climate system from regional to global scale. Geomagnetic reversals are regarded as excellent age constraints because they are global events and independent from climatic conditions. However, spatial variations of timing and internal dynamics of reversals may limit their precision. Our 1.2 Ma high‐resolution (~25 cm/kyr) sediment record from Lake Ohrid is promising to precisely depict the Matuyama‐Brunhes (MB) reversal and the Jaramillo subchron. Two generations of diagenetic ferrimagnetic minerals are present in glacial intervals of the Lake Ohrid record. Early diagenetic greigite acquired a quasi synsedimentary chemical magnetization, while a late diagenetic greigite formation, triggered by the upward diffusion of H2S‐rich waters, obscures the polarity record at the top of the Jaramillo. Interglacial intervals are unaffected by greigite formation, likely due to low iron concentrations. Based on an orbitally tuned age model with tephrostratigraphic markers, the base of Jaramillo can be precisely dated to 1072.4 ka, and the MB reversal to 778.5 ka. Both polarity reversals occurred very rapidly in our record, lasting 2.3 and 1 kyr, respectively. Our results reveal that the dipole component of the Earth's magnetic field fell below the nondipole components only for a short duration in the Mediterranean region. The comparison of the timing of the MB boundary across different archives implies that the onset of the reversal provides a more synchronous age marker compared to often used midpoint ages. Key Points: Two generations of diagenetic greigite occur in Lake Ohrid sediments but are constrained to glacial intervalsPaleomagnetic reversal processes took less than 1 kyr for the Matuyama‐Brunhes reversal and 2.3 kyr for the base of the Jaramillo subchronThe onset of the Matuyama‐Brunhes reversal is spatially more synchronous than its midpoint and should be used for stratigraphic correlation [ABSTRACT FROM AUTHOR]

A group‐theoretical framework to describe vacancy ordering and magnetism in the Fe1−xS system is developed. This framework is used to determine the sequence of crystal structures consistent with the observed magnetic structures of troilite (FeS), and to determine the crystallographic nature of the low‐temperature Besnus transition in Fe0.875S. It is concluded that the Besnus transition is a magnetically driven transition characterized by the rotation of the moments out of the crystallographic plane to which they are confined above the transition, accompanied by small atomic displacements that lower the symmetry from monoclinic to triclinic at low temperatures. Based on the phase diagram, magnetically driven phase transitions at low temperatures are predicted in all the commensurate superstructures of pyrrhotite. Based on the phase diagram, magnetically driven spin reorientations at low temperatures are predicted in all the commensurate superstructures of pyrrhotite. The exact nature of the spin rotation is determined by the symmetry of the vacancy‐ordered state and based on this spin‐flop transitions in 3C and 5C pyrrhotite and a continuous rotation akin to that seen in 4C pyrrhotite are predicted. A Besnus‐type transition is also possible in 6C pyrrhotite. Furthermore, it is clarified that 3C and 4C pyrrhotite carry a ferrimagnetic moment whereas 5C and 6C are antiferromagnetic. [ABSTRACT FROM AUTHOR]

Reactions of [Mn(H2dapsc)Cl2]⋅H2O (dapsc=2,6‐ diacetylpyridine bis(semicarbazone)) with K3[Fe(CN)6] and (PPh4)3[Fe(CN)6] lead to the formation of the chain polymeric complex {[Mn(H2dapsc)][Fe(CN)6][K(H2O)3.5]}n⋅1.5n H2O (1) and the discrete pentanuclear complex {[Mn(H2dapsc)]3[Fe(CN)6]2(H2O)2}⋅4 CH3OH⋅3.4 H2O (2), respectively. In the crystal structure of 1 the high‐spin [MnII(H2dapsc)]2+ cations and low‐spin hexacyanoferrate(III) anions are assembled into alternating heterometallic cyano‐bridged chains. The K+ ions are located between the chains and are coordinated by oxygen atoms of the H2dapsc ligand and water molecules. The magnetic structure of 1 is built from ferrimagnetic chains, which are antiferromagnetically coupled. The complex exhibits metamagnetism and frequency‐dependent ac magnetic susceptibility, indicating single‐chain magnetic behavior with a Mydosh‐parameter φ=0.12 and an effective energy barrier (Ueff/kB) of 36.0 K with τ0=2.34×10−11 s for the spin relaxation. Detailed theoretical analysis showed highly anisotropic intra‐chain spin coupling between [FeIII(CN)6]3− and [MnII(H2dapsc)]2+ units resulting from orbital degeneracy and unquenched orbital momentum of [FeIII(CN)6]3− complexes. The origin of the metamagnetic transition is discussed in terms of strong magnetic anisotropy and weak AF interchain spin coupling. [ABSTRACT FROM AUTHOR]

Formation of radical–radical cocrystals is an important step towards the design of organic ferrimagnets. We describe a simple approach to generate radical–radical cocrystals through the identification and implementation of well‐defined supramolecular synthons which favor cocrystallization over phase separation. In the current paper we implement the structure‐directing interactions of the E−E bond (E=S, Se) of dithiadiazolyl (DTDA) and diselenadiazolyl (DSDA) radicals to form close contacts to electronegative groups. This is exemplified through the preparation and structural characterization of three sets of radical cocrystals; the 2:2 cocrystal [PhCNSSN]2[MBDTA]2 (4) [MBDTA=methyl benzodithiazolyl] and the 2:1 cocrystals [C6F5CNEEN]2[TEMPO] (E=S, 5; E=Se, 6). In 4 the two types of radical are linked via bifurcated inter‐dimer δ+S⋅⋅⋅Nδ− interactions whereas 5 and 6 exhibit a set of five‐centre δ+E⋅⋅⋅Oδ− contacts (E=S, Se). [ABSTRACT FROM AUTHOR]

Abstract: Garnet, as a major constitutive mineral of eclogite, is important for Sm–Nd dating of eclogite due to its high Sm/Nd ratio and its stability during retrogression. However, a comprehensive study of the petrography, mineral chemistry, garnet water content, and Sm–Nd isotopic composition of eclogites from the Bixiling massif, Central Dabie Zone (CDZ), reveals significant modification of the Sm–Nd isotopic system in garnet as a result of retrogression. This problem constitutes a challenge for Sm–Nd dating of the Bixiling eclogites, with the Sm–Nd isochron ages of 218 ± 4 to 210 ± 9 Ma reported in the literature being younger than 226 ± 3 Ma, which is the generally accepted peak metamorphic age of the CDZ. Petrographic analysis reveals heterogeneity in colour within single fractured garnet grains. There are light‐pink garnet (Grt‐P) and red garnet (Grt‐R) types that possess distinct chemical compositions. Compared to Grt‐P, Grt‐R has higher Fe and andradrite contents but lower Al and grossular contents. Grt‐P also has lower water contents (15–35 ppm) than Grt‐R (34–65 ppm), which, together with the spatial association between Grt‐R and fractures, suggests that the colour change is related to fluid alteration. Grt‐P is an ultra‐high‐pressure (UHP) mineral, and Grt‐R is the product of the interaction between Grt‐P and a fluid during retrogression. Moreover, Grt‐R features lower Sm and Nd contents but higher Sm/Nd ratios than Grt‐P. The Sm–Nd isochrons defined by UHP minerals (Grt‐P+Omp+Rt or Grt‐P+Cpx+WR) from three eclogite samples yield consistent ages of 226.0 ± 3.8 Ma, 225.0 ± 3.9 Ma and 226.2 ± 6.9 Ma, which are identical to the peak metamorphic age of 226 ± 3 Ma for the CDZ. The retrogressed garnet (i.e., Grt‐R), omphacite and rutile, together define a pseudoisochron with younger ages of 218.9 ± 5.9 to 202.8 ± 4.8 Ma, which are geologically meaningless. The increase in the Sm/Nd ratio with constant or lower 143Nd/144Nd ratios during the transformation of Grt‐P to Grt‐R was probably the cause of these younger ages. [ABSTRACT FROM AUTHOR]

Abstract: Magnetically contrasted granular hetero‐nanostructures are prepared by seed‐mediated growth in polyol, properly combining two oxide phases with different magnetic order, ferrimagnetic (F) partially oxidized magnetite Fe3−xO4 and antiferromagnetic (AF) cobalt oxide. Spinel Fe3−xO4 nanoparticles are first synthesized and then used as seeds for rock salt CoO nanocrystals growth. Three different hetero‐nanostructure designs are realized, acting on the content ratio between the seeds and the deposit's precursors during the synthesis. For all of them, the spinel and the rock salt phases are confirmed by X‐ray diffraction and high‐resolution transmission electron microscopy. Both phases are obtained in high‐crystalline quality with a net epitaxial relationship between the two crystallographic lattices. Mössbauer spectrometry confirms the cobalt cation diffusion into the spinel seeds, giving favorable chemical interfacing with the rock salt deposit, thus prevailing its heterogeneous nucleation and consequently offering the best condition for exchange‐bias (EB) onset. Magnetic measurements confirm EB features. The overall magnetic properties are found to be a complex interplay between dipolar interactions, exchange anisotropy at the F/AF interface, and magnetocrystalline anisotropy enhancement in the F phase, due to Co2+ diffusion into iron oxide's crystalline lattice. These results underline the powerfulness of colloidal chemistry for functional granular hetero‐nanostructured material processing. [ABSTRACT FROM AUTHOR]

The history of the oxo compounds of iron in its highest oxidation states is reviewed and modern activities in this long neglected area of inorganic chemistry are highlighted. The chemistry of ferrates(VI) is the most rapidly advancing branch owing to several potential applications in diverse fields such as environmental chemistry and energy storage. Convenient and high-yield preparations of ferrates( VI) in high purity are presented, followed by a coverage of the analytical, spectroscopic, and structural characterization in the solid and in solution, with a focus on the stability of these compounds, which had long been under-estimated. Particular attention has been paid to the fascinating mechanisms that have been proposed for the intriguing "self-decay" of the [FeO4]2- dianion. Redox processes with inorganic and organic substrates are summarized including fresh and waste water treatment on the one hand and "super-iron batteries" on the other. Recent advances in the experimental and computational approach to ferrates(VII) [FeO4]- and the elusive "iron tetroxide" [FeO4] are described. [ABSTRACT FROM AUTHOR]

The history of the oxo compounds of iron in its highest oxidation states is reviewed and modern activities in this long neglected area of inorganic chemistry are highlighted. The chemistry of ferrates(VI) is the most rapidly advancing branch owing to several potential applications in diverse fields such as environmental chemistry and energy storage. Convenient and high-yield preparations of ferrates( VI) in high purity are presented, followed by a coverage of the analytical, spectroscopic, and structural characterization in the solid and in solution, with a focus on the stability of these compounds, which had long been under-estimated. Particular attention has been paid to the fascinating mechanisms that have been proposed for the intriguing "self-decay" of the [FeO4]2- dianion. Redox processes with inorganic and organic substrates are summarized including fresh and waste water treatment on the one hand and "super-iron batteries" on the other. Recent advances in the experimental and computational approach to ferrates(VII) [FeO4]- and the elusive "iron tetroxide" [FeO4] are described. [ABSTRACT FROM AUTHOR]

A rigorous electrodynamic approach to the modeling of ferromagnetic resonance (FMR) in ferrimagnetic films of arbitrary thickness placed in a rectangular microwave cavity is presented in this letter. It is shown that the coupling of the cavity mode with the FMR mode of an in‐plane magnetized ferrimagnetic film occurs when the real part of its intrinsic diagonal permeability component µ approaches zero. The obtained theoretical prediction of frequency vs. magnetic bias is confirmed by experiments performed on a 3 µm thin yttrium iron garnet (YIG) layer grown on a 500 µm thick gadolinium gallium garnet (GGG) substrate for both even and odd cavity modes. It is also shown that the proposed rigorous electrodynamic approach agrees well with perturbation theory in the high damping regime, however, leads to qualitatively different conclusions for low damping. Finally, it is demonstrated that the experimentally observed higher‐order FMR modes can be attributed to the longitudinal modes distributed across the thickness of the film at frequencies corresponding to negative values of µ approaching zero. This letter paves the way for further study of, among others, the magnon–microwave photon coupling strength and the development of ferromagnetic linewidth characterization methods. [ABSTRACT FROM AUTHOR]

Abstract: The large amount of generated waste determines the importance of their valorization. Red mud is the residue of the Bayer process, which stored cumulative value raises 2.7 Bt. This paper describes an easy way to produce a ferrimagnetic glass‐ceramic frit, using bauxite residue, fly ash and glass cullet as raw materials. The synthesized frit consists of faceted and dendritic agglomerated crystals of magnetite and titanomagnetite embedded in a glass matrix, which exhibits a saturation magnetization (MS) of 6.3 emu/g, a remanent magnetization (MR) of 2.7 emu/g and a coercive field (HC) of 347 Oe. Furthermore, it presents Vickers hardness value of HV = 5.55 ± 0.16 GPa and fracture toughness value of KIC = 1.64 ± 0.34 MPa·m1/2. [ABSTRACT FROM AUTHOR]

Two new heterobi‐ and trimetallic chains of formula ∞1[{MnII(pyim)2}{(µ‐NC)2WV(bipy)(CN)4}][WV(bipy)(CN)6] (1) and ∞1[{CuIIMnIIL}{(µ‐NC)3WV(bipy)(CN)3}][WV(bipy)(CN)6]·0.75H2O·2MeCN (2) were obtained by reacting the cyanido‐based AsPh4[W(bipy)(CN)6] heteroleptic complex with the pre‐formed [MnII(pyim)2]2+ (1) and [CuIIMnIIL]2+ (2) complexes [bipy = 2,2′‐bipyridine, pyim = 2‐(1H‐imidazol‐2‐yl)pyridine and H2L = macrocyclic Schiff‐base resulting from the stepwise condensation of 2,6‐diformyl‐p‐cresol with ethylenediamine and diethylenetriamine]. The structure of 1 consists of cationic cyanido‐bridged {MnIIWV} chains, assembled from [WV(bipy)(CN)6]– spacers, each one coordinating in a bis‐monodentate fashion, two [MnII(pyim)2]2+ nodes, and [WV(bipy)(CN)6]– counteranions. Compound 2 comprises a positively charged 1D coordination polymer, built from [WV(bipy)(CN)6]– cyanido metalloligands that act as tris‐monodentate spacers towards [CuIIMnIIL]2+ complexes, the entire assembly being neutralized by [WV(bipy)(CN)6]– anions. Each manganese(II) ion in 1 is six‐coordinate in a somewhat distorted octahedral surrounding. Five‐coordinate copper(II) and seven‐coordinate manganese(II) ions exhibiting distorted square pyramidal and monocapped trigonal prism environments respectively, occur in each {CuIIMnII} node of 2. The magnetic susceptibility of 1 and 2 investigated down to 1.9 K is characteristic of 1D ferrimagnetic behavior with minima in the χMT vs. T plots at 35 (1) and 20 K (2) (χM is the magnetic susceptibility per one MnII plus two WV ions). The magnetic data of 1 in the whole temperature range were analyzed through a model considering SMn = 5/2 as a classical spin and SW = 1/2 as a quantum spin, with two interaction parameters J1 = J(1 – α) and J2 = J(1 + α) {the spin Hamiltonian being defined as H = –JΣiSW,i[(1 + α)SMn,j + (1 – α)SMn,i+1] + Σi(gWSW,i + gMnSMn,i)βH}. The values of the intrachain antiferromagnetic interactions for 1 through this model were –3.0(1) (J1) and –32.0(1) cm–1 (J2). The complexity of the spin topology in 2, a branched chain with four different intrachain antiferromagnetic interactions (double phenoxido bridge between MnII and CuII, two single cyanido bridges between MnII and CuII, and one single cyanido bridge between CuII and WV) precluded any simulation of its magnetic data. [ABSTRACT FROM AUTHOR]

The electronic and thermoelectric properties of two phases of calcium cobaltite, a misfit layered compound, are investigated and compared using first-principles DFT calculations. The two phases considered here include the conventional bulk phase that consists of alternating layers of Ca2CoO3 and CoO2, and a new phase that consists of alternating layers of CaCoO2 and CoO2, which was recently discovered in nanotubes. Electronic structure calculations reveal that both phases are ferrimagnetic materials with one important difference: the bulk phase is metallic, whereas the nanotubular phase is semiconducting. The metal-to-semiconductor transition that accompanies the Ca2CoO3 to CaCoO2 structural transition is shown to arise from the depletion of free carriers from the donor Ca atoms. The implications of the difference in electronic structure for the thermoelectric performance of these two phases are further examined with Boltzmann transport calculations. Relative to the metallic phase, the semiconducting phase displays appreciably higher Seebeck coefficients at minimal doping levels; these increased Seebeck coefficients compensate for the reduced conductivity and result in large power factors. In conjunction with the fact that the semiconducting phase is peculiar to 1D nanotubes, it is expected that additional effects from quantum confinement could render these low-dimensional materials as promising thermoelectric materials. [ABSTRACT FROM AUTHOR]