Kitaev interactions through extended superexchange pathways in the Ru honeycomb magnet RuPSiO.

Magnetic materials are composed of the simple building blocks of magnetic moments on a crystal lattice that interact via magnetic exchange. Yet from this simplicity emerges a remarkable diversity of magnetic states. Some reveal the deep quantum mechanical origins of magnetism, for example, quantum spin liquid (QSL) states in which magnetic moments remain disordered at low temperatures despite being strongly correlated through quantum entanglement.

Low-Temperature Ferromagnetic Order in a Two-Level Layered Co Material.

The magnetic properties of a 2D layered material consisting of high-spin Co complexes, [Co(NHNH)(HO)Cl]Cl ( ), have been extensively characterized using electron paramagnetic resonance, magnetic susceptibility, and low-temperature heat capacity measurements. Electron paramagnetic resonance spectroscopy studies suggest that below 50 K, the = 3/2 orbital triplet state of Co is gradually depopulated in favor of the = 1/2 spin state, which is dominant below 20 K. In light of this, the magnetic susceptibility has been fitted with a two-level model, indicating that the interactions in this material are much weaker than previously thought.

Unveiling the structural phase transition and magnetic structure of ternary boride PrIrB.

We present a comprehensive study of PrIrB, which includes a detailed investigation of its crystal and magnetic structure using neutron diffraction. AC and DC magnetization and heat capacity data reveal antiferromagnetic ordering at= 10 K. The heat capacity measurements further exhibit a broad peak near 270 K which is related to a structural transition from6/to2/seen in low temperature x-ray diffraction and neutron diffraction.

Counting the Acid Sites in a Commercial ZSM-5 Zeolite Catalyst.

This work investigates the acid sites in a commercial ZSM-5 zeolite catalyst by a combination of spectroscopic and physical methods. The Brønsted acid sites in such catalysts are associated with the aluminum substituted into the zeolite lattice, which may not be identical to the total aluminum content of the zeolite. Inelastic neutron scattering spectroscopy (INS) directly quantifies the concentrations of Brønsted acid protons, silanol groups, and hydroxyl groups associated with extra-framework aluminum species.

Phase Transitions and Physical Properties of the Mixed Valence Iron Phosphate Fe(POOH)(HO).

Iron phosphate materials have attracted a lot of attention due to their potential as cathode materials for lithium-ion rechargeable batteries. It has been shown that lithium insertion or extraction depends on the Fe mixed valence and reduction or oxidation of the Fe ions' valences. In this paper, we report a new synthesis method for the Fe(POOH)(HO) mixed valence iron phosphate.

Terahertz Faraday Rotation of SrFeO Hexaferrites Enhanced by Nb Doping.

The magneto-optical and dielectric behavior of M-type hexaferrites as permanent magnets in the THz band is essential for potential applications like microwave absorbers and antennas, while are rarely reported in recent years. In this work, single-phase SrFeNbO hexaferrite ceramics were prepared by the conventional solid-state sintering method. Temperature dependence of dielectric parameters was investigated here to determine the relationship between dielectric response and magnetic phase transition.

Magnetic Phase Separation in the Oxypnictide SrCrMnAsO.

Layered SrMAsO-type oxypnictides are composed of tetrahedral MPn and square planar MO layers, the building blocks of iron-based and cuprate superconductors. To further expand our understanding of the chemical and magnetic properties of the SrCrMnAsO solid solution, SrCrMnAsO has been synthesized. The compound crystallizes in the 4/ tetragonal space group with a refined stoichiometry of SrCrMnAsO.

Localized Spin Dimers and Structural Distortions in the Hexagonal Perovskite BaCaMoO.

Extended solid-state materials based on the hexagonal perovskite framework are typified by close competition between localized magnetic interactions and quasi-molecular electronic states. Here, we report the structural and magnetic properties of the new six-layer hexagonal perovskite BaCaMoO. Neutron diffraction experiments, combined with magnetic susceptibility measurements, show that the MoO dimers retain localized character down to 5 K and adopt nonmagnetic spin-singlet ground states.

Tuneable magnetic nanocomposites for remote self-healing.

When polymer composites containing magnetic nanoparticles (MNPs) are exposed to an alternating magnetic field, heat is generated to melt the surrounding polymer locally, partially filling voids across any cracks or deformities. Such materials are of interest for structural applications; however, structural polymers with high melting temperatures pose the challenge of generating high localised temperatures enabling self-healing. A method to prepare a multiferroic-Polyamide 6 (PA6) nanocomposite with tuneable magnetocaloric properties is reported.

Quantum Spin-1/2 Dimers in a Low-Dimensional Tetrabromocuprate Magnet.

This work describes a homometallic spin- tetrabromocuprate adopting a bilayer structure. Magnetic-susceptibility measurements show a broad maximum centred near 70 K, with fits to this data using a Heisenberg model consistent with strong antiferromagnetic coupling between neighbouring copper atoms in different layers of the bilayer. There are further weak intralayer ferromagnetic interactions between copper cations in neighbouring dimers.

Elemental composition, heat capacity from 2 to 300 K and derived thermodynamic functions of 5 microorganism species.

Detailed elemental analysis and low-temperature calorimetric measurement results are reported for the first time for Gram-positive bacteria, Gram-negative bacteria and mold fungi. Microorganism unit carbon formulas (empirical formulas) were calculated. Standard molar heat capacity and entropy were found to be C⁰ = 38.

Effect of thermal treatment on the stability of Na-Mn-W/SiO catalyst for the oxidative coupling of methane.

In this study, we investigate the effect of thermal treatment/calcination on the stability and activity of a Na-Mn-W/SiO catalyst for the oxidative coupling of methane. The catalyst performance and characterisation measurements suggest that the W species are directly involved in the catalyst active site responsible for CH conversion. Under operating conditions, the active components, present in the form of a Na-W-O-Mn molten state, are highly mobile and volatile.

Electronic and Magnetic Properties of Cation Ordered SrMnCrAsO.

Several different mechanisms of magnetoresistance (MR) have been observed in 1111 LnMnAsOF oxypnictides (Ln = lanthanide) as a result of magnetic coupling between the Mn and Ln. Such phases also exhibit interesting magnetic phase transitions upon cooling. SrMnCrAsO has been synthesized to investigate if it is possible to observe MR and/or magnetic phase transitions as a result of magnetic coupling between the Mn and Cr.

Evidence of 2D anti-ferromagnetic ordering in rare-earth Langmuir-Blodgett films.

In recent years the ordering of spins in two-dimensions has received considerable attention due to both the fundamental physics interest and for the possible technological applications. Langmuir-Blodgett (LB) films with magnetic ions are ideal systems to study two-dimensional (2D) magnetic ordering as the distances of the magnetic-ions along the out-of-plane and in-plane directions differ by almost an order of magnitude and the effect of the substrate can be neglected. In particular, vortex formation in ferro and antiferro 2D magnetic structures are of current interest and LB films are ideal to study this evolving physics.

High-Pressure Study of the Elpasolite Perovskite LaNiMnO.

Here we report a high-pressure investigation into the structural and magnetic properties of the double perovskite LaNiMnO using neutron scattering over a temperature range of 4.2-300 K at ambient pressure and over a temperature range of 120-1177 K up to a maximum pressure of 6.6 GPa.

Magnetic interactions in the S = 1/2 square-lattice antiferromagnets BaCuTeO and BaCuWO: parent phases of a possible spin liquid.

The isostructural double perovskites BaCuTeO and BaCuWO are shown by theory and experiment to be frustrated square-lattice antiferromagnets with opposing dominant magnetic interactions. This is driven by differences in orbital hybridisation of Te and W. A spin-liquid-like ground state is predicted for BaCu(TeW)O solid solution similar to recent observations in SrCu(TeW)O.

[Ge(TeBu)] - a single source precursor for the chemical vapour deposition of germanium telluride thin films.

Reaction of activated germanium with nBu2Te2 in THF solution was shown to be more effective for the preparation of the germanium(iv) tellurolate compound, [Ge(TenBu)4], than reaction of GeCl4 with LiTenBu in a 1 : 4 molar ratio in THF. The product was characterised by 1H, 13C{1H} NMR spectroscopy and microanalysis and evaluated as a single source precursor for the low pressure chemical vapour deposition of GeTe thin films. Depending upon deposition conditions, either dull grey films (predominantly elemental Te) or highly reflective (GeTe) films were obtained from the pure precursor.

Tin(iv) chalcogenoether complexes as single source precursors for the chemical vapour deposition of SnE and SnE (E = S, Se) thin films.

The molecular Sn(iv) complexes, [SnCl{BuS(CH)SBu}] (2), [SnCl(BuS)] (3) and [SnCl(BuSe)] (4) have been prepared in good yield from reaction of SnCl with the appropriate chalcogenoether ligand in anhydrous hexane and, together with the known [SnCl{BuSe(CH)SeBu}] (1), employed as single source precursors for the low pressure chemical vapour deposition of the corresponding tin dichalcogenide thin films. At elevated temperatures the bidentate ligand precursors, (1) and (2), also form the tin monochalcogenides, SnSe and SnS, respectively. In contrast, (3) gave a mixture of phases, SnS, SnS and SnS and (4) gave SnSe only.

Investigation of the role of morphology on the magnetic properties of CaMnO materials.

CaMnO exhibits a complex layered structure comprised of MnO layers separated by Ca ions. In contrast with the more traditional triangular delafossite layered materials the MnO layers additionally exhibit an ordered vacancy, which forms a 'bow-tie' like arrangement of the Mn ions. We report a comprehensive study of the magnetic properties of a series of CaMnO materials with different morphologies.

PZT-like structural phase transitions in the BiFeO3-KNbO3 solid solution.

Despite the high prominence of the perovskites BiFeO(3) and KNbO(3) the solid solution between the two has received little attention. We report a detailed neutron and synchrotron X-ray powder diffraction, and Raman spectroscopy study which demonstrates an R3c→P4mm→Amm2 series of structural phase transitions similar to that exhibited by the PbZrO(3)-PbTiO(3) solid solution.