The ferrocell is an optical viewing device that interacts with a magnetic field and one or more light sources to produce a real-time visual light display. Although this device has been extensively studied by several researchers, a proper computer simulation replicating this optical effect has not yet been presented. Using numerical methods and the law of reflection, a computer simulation was developed that shows that the light patterns as seen in the ferrocell are primarily caused by light reflections off the ferrofluid nano-particles that self organize into needle-like filaments and align along magnetic flux lines in the presence of a magnetic field.

Monolayered MoS₂ is energetically most stable when it has a 1H phase, but 1H to 1T phase transition (1H→1T) is easily realized by various ways. Even though magnetic moment is not observed during 1H1T, 0.049 µB/MoS₂ is obtained in local 1T phase; 75% 2H and 25% 1T phases are mixed in (2×2) supercell. Furthermore, non-negligible magnetocrystalline anisotropy (MCA) energy is occured. Most magnetic moment as well as MCA are originated by 1T phased Mo atom5 in the supercell, while electronic structures of other atoms are similar to non-magnetic. Due to this, magnetic/non-magnetic boundary is created in the monolayered MoS2. Our result suggests that MoS₂ can be applied for spintronics such as a spin transistor.

The present work reports on the calculated electronic and magnetic structure of the binary Co-Ga system at high Co content. β-CoGa adopts a simple cubic CsCl type structure. Well-ordered CoGa does not exhibit collective magnetism but is a paramagnetic, metallic compound. Neither Co nor Ga deficiency induces magnetic order, however, ferromagnetism is observed for Co-Ga anti-site disorder. The magnetic moment per cell increases up to about 1.2 μB in the completely disordered body centered cubic structure. With increasing Co content, Co1+xGa1−x maintains the CsCl type structure and becomes ferromagnetic. Most important, a discontinuity of the magnetic order with composition is observed at about 10% excess Co, where a change from a low magnetic moment state to a high moment state is observed. This is accompanied by a change in the electronic structure and transport properties. The discontinuity is forced by the increasing exchange splitting related to the localized moment of the additional Co atoms that replace Ga. Subsequently, the magnetic moment increases continuously up to 2.5 μB for x=0.6. For x≳0.6, the structure changes to face centered cubic with random site occupation and the magnetic moment further increases. Above the magnetic discontinuity, the Curie temperature increases linearly with the Co content from the onset of ferromagnetism, until it reaches its maximum in pure Co.

Lacunary polyoxometalates (POMs) are negatively charged metal−oxo clusters, formally obtained from plenary topologies via fragment removal. Owing to the fragment removal, the lacunary POMs archetypes are rich in nucleophilic terminal oxo ligands, making them suitable for post-synthetic coordination with various heterometals. Trilacunary heteropolytungstates (het-ero-POTs) based on bowl-shaped {W9O30} framework incorporating a central lone-pair containing {XO3} hetergroup (X = AsIII, SbIII, and BiIII) function as all-inorganic scaffolds that in the presence of d-block metal cations typically construct sandwich-like dimers of Hervé and/or Krebs. Herein we review the preparative approaches, compositional and magnetic versatility of the constructing Hervé and Krebs type dimers and discuss prospective use as POMtronics.

Living organisms with developed endocrine systems react in a complex way to environmental changes. Changing atmospheric pressure causes different blood pressures or hormone levels; carcinogenic radiation modifies the structure of DNA. Charged particles and ions act as neurotransmitters and block certain types of protein channels and receptors. A high concentration of carbon dioxide has an indirect effect on both blood pressure and neuron activity. The bioelectric nature of living tissues highlights the complexity of the connection between the dynamic physical environment and biological systems. Recent results from studies on the interactions and connections mentioned above are reviewed in this paper.

Four decades have elapsed since the first quasiperiodic crystal was discovered in the Al-Mn alloy system, and many progresses have been made during this time interval in the science of quasicrystals (QCs). Notwithstanding this, a significant number of open questions still remain regarding both fundamental and technological aspects. For instance: What are QCs good for? How can we improve the current provisional QC definition? What is the role of the underlying quasiperiodic order and the characteristic inflation symmetry of these compounds in the emergence of their unusual physicochemical properties? or, What is the nature of chemical bonding in QCs formed in such different sorts of materials as alloys, oxides, or organic polymers? In this essay I will discuss these, and other closely related, issues from an interdisciplinary perspective and will comment on appealing prospectives in the field for the years to come.

Fe[C5H5N]2[N(CN)2]2 (1) was synthesized from a reaction of stoichiometric amounts of NaN(CN)2 and FeCl2·4 H2O in a methanol/pyridine solution. Single-crystal and powder diffraction show that 1 crystallizes in the monoclinic space group I2/m (no. 12), different from Mn[C5H5N]2[N(CN)2]2 (P21/c, no. 14) due to tilted pyridine rings, with a = 7.453(7) Å, b = 13.167(13) Å, c = 8.522(6) Å, β = 114.98(6)° and Z = 2. ATR-IR, AAS, and CHN measurements confirm the presence of dicyanamide and pyridine. Thermogravimetric analysis shows that π-stacking interactions of the pyridine rings play an important role in structural stabilization. Based on DFT-optimized structures, a chemical bonding analysis was performed using a local-orbital framework by projection from a plane-wave basis. The resulting bond orders and atomic charges are in good agreement with the expectations based on the structure analysis. SQUID magnetic susceptibility measurements show a high-spin state FeII compound with predominantly antiferromagnetic exchange interactions at lower temperatures.

Using the unique combination of atomically resolved atom probe tomography (APT) and volume averaged neutron (resonance) spin echo (NRSE and NSE) experiments, the influence of nano-scaled clusters on the spin relaxation in spin glasses was studied. For this purpose, the phase transition from the paramagnetic phase to the spin glass phase in a Fe-Cr spin glass with a composition of Fe_17.8Cr_82.2 was studied in detail by means of NRSE. The microstructure was characterised by APT measurements, which show local concentration fluctuations of Fe and Cr on a length scale of 2 to 5 nm, which lead i) to the coexistence of ferro- and anti-ferromagnetic clusters and ii) a change of the magnetic properties of the whole sample, even in the spin glass phase, where spins are supposed to be randomly frozen. We show that a generalized spin glass relaxation function, which was successfully used to describe the phase transition in diluted spin glasses, can also be used for fitting the spin dynamics in spin glasses with significant concentration fluctuations.

Iron oxide nanoparticles have been investigated due to their suitable characteristics for diverse applications in the fields of biomedicine, electronics, water/wastewater treatment and sensors. Maghemite, magnetite and hematite are the most widely studied iron oxide particles and have ferrimagnetic characteristics. When very small, however, these particles have superparamagnetic properties and are called superparamagnetic iron oxide nanoparticles (SPIONs). Several methods are used for the production of these particles, such as coprecipitation, thermal decomposition and microemulsion. However, the variables of the different types of synthesis must be assessed to achieve greater control over the particles produced. In some studies, it is possible to compare the influence of variations in the factors for production with each of these methods. Thus, researchers use different adaptations of synthesis based on each objective and type of application. With coprecipitation, it is possible to obtain smaller, more uniform particles with adjustments in temperature, pH and the types of reagents used in the process. With thermal decomposition, greater control is needed over time, temperature as well as the proportion of surfactants and organic and aqueous phases in order to produce smaller particles and a narrower size distribution. With the microemulsion process, the control of the confinement of the micelles formed during synthesis through the proportions of surfactant and oil makes the final particles smaller and less dispersed. These nanoparticles can be used as additives for the creation of new materials, such as magnetic bacterial cellulose, which has different innovative applications. Composites that have SPIONs, which are produced with greater rigour with regards to size and distribution, have superparamagnetic properties and can be used in medical applications, whereas materials containing larger particles have ferromagnetic applications. To arrive at a particular particle with specific characteristics, researchers must be attentive to both the mechanism selected and the production variables to ensure greater quality and control of the materials produced.

Traditionally, neutron scattering is an essential method for the analysis of spin structures and spin excitations in bulk materials. Over the last 30 years, polarized neutron scattering in terms of reflectometry has also contributed largely to the analysis of magnetic thin films and magnetic multilayers. More recently it has been shown that polarized neutron reflectivity is, in addition, a suitable tool for the study of thin films laterally patterned with magnetic stripes or islands. We provide a brief overview of the fundamental properties of polarized neutron reflectivity, considering different domain states, domain fluctuations, and different domain sizes with respect to the neutron coherence volume. The discussion is exemplified by a set of simulated reflectivities assuming either complete polarization and polarization analysis, or a reduced form of polarized neutron reflectivity without polarization analysis. Furthermore, we emphasize the importance of the neutron coherence volume for the interpretation of specular and off-specular intensity maps, in particular when studying laterally non-homogeneous magnetic films. Finally, experimental results, fits, and simulations are shown for specular and off-specular scattering from a magnetic film that has been lithographically patterned into a periodic stripe array. These experiments demonstrate the different and mutually complementary information that can be gained when orienting the stripe array parallel or perpendicular to the scattering plane.

Electroactive microorganisms have received a lot of interest in the field of environmental engineering and biotechnology because of their extracellular electron transfer (EET) capability of energy recovery and environmental remediation. However, the low efficiency of EET remains a barrier to its practical implementation. This review presents an introduction to EET, followed by addressing strategies for enhancing EET through different approaches including enhancing EET by mediator materials, external electricity, photo, and magnetism as well as integrated strategies, that is, the combination of multiple means to promote extracellular electron transport and improve the performance of microbial electrochemical systems. Finally, the challenges, perspectives, and new directions for EET enhancement will be discussed.

Two mononuclear Ru(III) complexes of formula trans-[RuCl4(Hgua)(dmso)]·2H2O (1) and trans-[RuCl4(Hgua)(gua)]·3H2O (2) [Hgua = protonated guanine (gua), dmso = dimethyl sulfoxide] have been synthesized and characterized magnetostructurally. Compounds 1 and 2 crystallize in the monoclinic system with space groups P21/n and Pc, respectively. Each Ru(III) ion in 1 and 2 is six-coordinate and bonded to four chloride ions and one (1) or two (2) nitrogen atoms from guanine molecules and one sulfur atom (1) of a dmso solvent molecule, generating quasi regular octahedral geometries in both cases. In their crystal packing, the Ru(III) complexes are self-assembled mainly through an extended network of N-H⋯Cl hydrogen bonds and π⋯Cl type intermolecular interactions, forming novel supramolecular structures based on this paramagnetic 4d metal ion. Variable-temperature dc magnetic susceptibility measurements performed on microcrystalline samples of 1 and 2 show a different magnetic behavior. While 1 is a ferromagnetic compound at low temperature, 2 exhibits a behavior typical of noninteracting mononuclear Ru(III) complexes with S = 1/2. Ac magnetic susceptibility measurements reveal slow relaxation of the magnetization in the presence of external dc fields only for 2, hence indicating the occurrence of field-induced single-ion magnet (SIM) phenomenon in this mononuclear guanine-based Ru(III) complex.

Heterometallic rare-earth clusters have garnered much attention because of their interest-ing solid-state structures and versatile applications in catalysis and material and polymer chemistry over the last four decades. Particular interest is rare earth–transition metal co-ordination compounds that behave as single-molecule magnets (SMMs) because of their potential use in information storage, spintronic devices, and magnetic refrigeration sys-tems. Another implementation involves using lanthanide clusters in luminescent-based sensing for environmental protection and security screening or in photocatalytic energy conversion reactions. Heterometallic rare earth complexes offer the promise of catalytic performance of many organic reactions due to their high oxygenophilicity, Lewis acidity, high coordination numbers, and ability to change the coordination environment quickly. Therefore, they are commonly applied as catalysts in asymmetric synthesis, oxidation re-actions, and CO2 conversions or as initiators in ring-opening polymerization and copoly-merization of cyclic monomers. They are also attractive single-source molecular precur-sors for functional inorganic materials. This review focused on the unique features and properties of the heterometallic rare earth complexes, which are closely correlated with their molecular structure. Our summary is a valuable resource, providing researchers with an insightful exploration of the heterometallic rare-earth complexes that demonstrated multimetallic synergy and cooperativity effects in various applications.

Synthesis of heterodinuclear 3d transition metal complexes in which two metal ions are introduced in equivalent coordination sites of a ligand is quite uncommon. We have previously shown that the application of the cis-trans isomerization of the oxamido group was able to furnish such a possibility. In the present paper we demonstrate that this synthetic pathway, relying on the possibility of changing the conformation (cis vs trans) of the oxamido group, can be extended to other ligands. Although we have not been able to structurally characterize these complexes, EPR and magnetic data do confirm the efficiency of this reaction pathway. We also demonstrate that the cis-trans isomerization of the oxamido group is not due to a particular property of the ion involved in the reaction. In fact, isomerization is governed by the basicity of the reaction medium. According to the reaction condition, it is possible to favor or not this phenomenon, and to increase the accessibility to a larger number of novel genuine complexes. But the oxophilic character of the lanthanide ions impedes this isomerization in 3d-4f complexes. The very weak magnetic interactions observed in these Cu-Gd complexes can be explained thanks to spin polarization.

The magnetic properties of RCo3B2 compounds, with heavy rare earths, are investigated by using magnetic measurements and electronic structure calculations. The cobalt sublattice magnetizations are very small and antiparallel oriented to rare earths moments. Contributions of cobalt moments to the Curie constants were also shown. The cobalt magnetic behavior has been analyzed in spin fluctuations model. The presence of short-range order above the Curie temperatures in RCo3B2 compounds with R=Tb, Dy, and Ho has been attributed to reminiscent R5d-Co3d interactions.

Magnetic force microscopy (MFM) is a widespread technique for imaging magnetic structures with a resolution of some 10 nanometers. MFM can be calibrated to obtain quantitative (qMFM) spatially resolved magnetization data in units of A/m by determining the calibrated point spread function of the instrument, its instrument calibration function (ICF), from a measurement of a well-known reference sample. Beyond quantifying the MFM data, a deconvolution of the MFM image data with the ICF also corrects the smearing caused by the finite width of the MFM tip stray field distribution. However, the quality of the calibration depends critically on the calculability of the magnetization distribution of the reference sample. Here, we discuss a Ti/Pt/Co multilayer stack which shows a stripe domain pattern as a suitable reference material. A precise control of the fabrication process combined with a characterization of the sample micromagnetic parameters allows to reliably calculate the sample’s magnetic stray field, proven by a very good agreement between micromagnetic simulations and qMFM measurements. A calibrated qMFM measurement using the Ti/Pt/Co stack as a reference sample is shown and validated and the application area for quantitative MFM measurements calibrated with the Ti/Pt/Co stack is discussed.

In this article, we have tried to extend the Neumann–Kopp law concerning the heat capacity of solid compounds to other physical observables for materials represented as mixtures of chemical compounds, alloys, and ceramics. The main goal of this study is to find the intervals of external or internal parameters for a solid compound, within which its physical observable - the magnetic transition temperature for this work, can be expressed in terms of the atomic or molar weighted sum of the magnetic transition temperatures of the constituent elements of a compound. Outside these intervals, we tried to figure out the structure of the variable by which the weighted sum should be multiplied. Thus, for USb–x(ThSb) mixtures with a mole fraction x from 0.36 to 0.55, the magnetic transition temperature of this mixture is expressed in term of the molar weighted sum of the temperature of uranium structural transition associated with a change in the magnetic properties of uranium and of the temperature at which the nature of the magnetic susceptibility of antimony changes. For the magnetic Laves phase compounds Er(Fe_0.8–xMn_0.2–yCo_x+y)₂, the Curie temperature of the compound is equal to the weighted sum of the Curie temperatures of all elements of the compound, except for Mn, at x = 0.1, y = 0 and y = 0.1. For the paramagnetic Curie temperature of intercalated dichalcogenides Cr_xМоSe₂, it can be expressed in terms of the weighted Neel temperature of chromium multiplied by a variable depending on x, on the atomic numbers of all elements of the compound, and on a parameter proportional to the derivatives with respect to x of the dichalcogenide’s crystal lattice parameters.

Single-molecule magnets (SMMs) have garnered significant interest in the field of molecular magnetism due to their unique magnetic properties at the nanoscale. These molecular systems exhibit magnetisation behaviour reminiscent of conventional bulk magnets but with distinct advantages such as size-dependent properties and potential applications in quantum computing and high-density data storage. However, challenges remain in harnessing their properties for practical applications, including their susceptibility to degradation and limited control over their assembly and organisation.

The article presents a technology for producing nitrogen-containing nanoporous biocarbon with high degree of elemental composition homogeneity, confirmed by electron spectroscopy. The research explores the relationship among the electronic characteristics of supramolecular nanoporous carbon, its porous structure, and the capacitance at its interface with the electrolyte. The obtained biocarbon is characterized by micro and mesopores, as evidenced by the results of studies by the method of nitrogen adsorption/desorption. The specific area of the available porous surface was found to be 1247 m2/g. Comparing this result with the data of small-angle X-ray scattering, we conclude that micropores are open while mesopores remain closed. This material was found to have a saturation magnetization σs of 1.4 A∙m2∙kg-1 and a coercive force Hc of 10 kA/m. The impedance studies of electrochemical cells of supercapacitors made of the experimental biocarbon were carried out. Equivalent electrical circuits of the studied electrochemical processes were constructed and characterized.

Vanadium(IV) chalcogenide materials are of increasing interest for use in catalysis and energy conversion-related applications. Since no ternary compounds are yet known in the V–Se–Te system, we studied ternary VwSeyTe2–y (w = 1.10, 1.13; y = 0.42, 0.72) phases crystallizing in space group P3m1 (no. 164). Two single-crystal specimens with differing compositions of a solid solution were obtained using the ceramic method. All products were characterized by either single-crystal or powder X-ray diffraction. The lattice parameters increase with rising tellurium content in accordance to the larger ionic radius of the tellurium anion compared to selenium. The chemical compositions were confirmed by energy dispersive X-ray spectroscopy. Further, magnetic measurements revealed mostly antiferromagnetic properties. Simultaneous differential scanning calorimetry/thermogravimetric analyses in nitrogen atmosphere showed endothermic decomposition accompanied by the formation of VN. The results of this work can serve as a basis for the synthesis of new phases in the V–Se–Te and related vanadium chalcogenide systems.

This study delves into the intricate interplay between cosmology and gravity in dilaton-based models, enhancing our understanding. Exploring boundary theories coupled to gravity, we derive a four-dimensional effective theory from the cosmological constant. Dilaton gravity is then scrutinized, revealing elegant solutions and insights into brane embedding. The analysis extends to probe scalar fields, employing the WKB approximation in both conformal and non-conformal cases. In summary, this work contributes to a nuanced understanding of the complex relationship between cosmology and gravity in dilaton-based frameworks.