Noncollinear Electric Dipoles in a Polar Chiral Phase of CsSnBr Perovskite.

Polar and chiral crystal symmetries confer a variety of potentially useful functionalities upon solids by coupling otherwise noninteracting mechanical, electronic, optical, and magnetic degrees of freedom. We describe two phases of the 3D perovskite, CsSnBr, which emerge below 85 K due to the formation of Sn(II) lone pairs and their interaction with extant octahedral tilts. Phase II (77 K < < 85 K, space group 2/) exhibits ferroaxial order driven by a noncollinear pattern of lone pair-driven distortions within the plane normal to the unique octahedral tilt axis, preserving the inversion symmetry observed at higher temperatures.

A Dy-based single ion magnet in a SrLaGaO matrix: enhanced parameters in an expanded crystal lattice.

Dy doped SrLaGaO exhibits unusually slow relaxation of magnetization determined by two widely separated excited Kramers doublets with a second remagnetization energy barrier of 223 cm. This value considerably exceeds that for analogous Ca(Y,Dy)AlO in spite of the apparently enlarged Dy coordination sphere.

Experimental and computational study of the exchange interaction between the V(III) centers in the vanadium-cyclal dimer.

[V(HCyclal)] is prepared by controlled oxidation of vanadium nanoparticles at 50 °C in toluene. The V(0) nanoparticles are synthesized in THF by reduction of VCl with lithium naphthalenide. They exhibit very small particle sizes of 1.

Salt-flux growth of HoCuMg single crystals.

Polycrystalline samples of the magnesium-rich intermetallic compounds RECuMg (RE = Dy, Ho, Er, Tm) were synthesized by reaction of the elements in sealed tantalum ampoules heated in a high-frequency induction furnace. Phase purity of the RECuMg phases was ascertained by powder X-ray diffraction patterns. Well-shaped single crystals of HoCuMg could be grown in a NaCl/KCl salt flux and the crystal structure was refined from single crystal X-ray diffraction data: TbCuMg structure-type, space group , = 1361.

Influence of Disorder on the Bad Metal Behavior in Polar Amalgams.

The two new ternary amalgams KRbHg [ = 0.472(7)] and CsCaHg [ = 0.20(3)] represent two different examples of how to create ternary compounds from binaries by statistical atom substitution.

High-Spin Orbital Interactions Across van der Waals Gaps Controlling the Interlayer Ferromagnetism in van der Waals Ferromagnets.

We examined what interactions control the sign and strength of the interlayer coupling in van der Waals ferromagnets such as FeGeTe, CrGeTe, CrI, and VI to find that high-spin orbital interactions across the van der Waals gaps are a key to understanding their ferromagnetism. Interlayer ferromagnetic coupling in FeGeTe, CrGeTe, and CrI is governed by the high-spin two-orbital two-electron destabilization, but that in VI by the high-spin four-orbital two-electron stabilization. These interactions explain a number of seemingly puzzling observations in van der Waals ferromagnets.

Superconductivity in (Ba,K)SbO.

(Ba,K)BiO constitute an interesting class of superconductors, where the remarkably high superconducting transition temperature T of 30 K arises in proximity to charge density wave order. However, the precise mechanism behind these phases remains unclear. Here, enabled by high-pressure synthesis, we report superconductivity in (Ba,K)SbO with a positive oxygen-metal charge transfer energy in contrast to (Ba,K)BiO.

Mechanochemical Synthesis and Magnetic Characterization of Nanosized Cubic Spinel FeCrS Particles.

Nanosized samples of the cubic thiospinel FeCrS were synthesized by ball milling of FeS and CrS precursors followed by a distinct temperature treatment between 500 and 800 °C. Depending on the applied temperature, volume weighted mean ( ) particle sizes of 56 nm (500 °C), 86 nm (600 °C), and 123 nm (800 °C) were obtained. All samples show a transition into the ferrimagnetic state at a Curie temperature of ∼ 167 K only slightly depending on the annealing temperature.

Crystal, electronic and magnetic structures of a novel series of intergrowth carbometalates RCoC (R = Y, Gd, Tb).

A series of new ternary isostructural RCoC (R = Y, Gd, Tb) carbides was synthesized by annealing of arc-melted stoichiometric samples. The crystal structure of TbCoC [space group P2/m, Pearson symbol mP18, a = 12.754(2) Å, b = 3.

Tb-based silicate apatites showing slow magnetization relaxation with identical parameters for the Tb and Dy counter ions.

Tb-diluted and Tb-rich apatite-type silicates with compositions YTbCa(SiO)O and TbCa(SiO)O, respectively, exhibit field induced multiple slow relaxation of magnetization. The former reveals two slow relaxation paths, the latter only one with a longer relaxation time of several seconds. The relaxation features of the Tb-diluted one are comparable with those of analogue compounds, where Tb is replaced by Dy, as well as with those of a Tb-doped calcium phosphate apatite.

Spin Exchanges Between Transition Metal Ions Governed by the Ligand p-Orbitals in Their Magnetic Orbitals.

In this review on spin exchanges, written to provide guidelines useful for finding the spin lattice relevant for any given magnetic solid, we discuss how the values of spin exchanges in transition metal magnetic compounds are quantitatively determined from electronic structure calculations, which electronic factors control whether a spin exchange is antiferromagnetic or ferromagnetic, and how these factors are related to the geometrical parameters of the spin exchange path. In an extended solid containing transition metal magnetic ions, each metal ion M is surrounded with main-group ligands L to form an ML polyhedron (typically, n = 3-6), and the unpaired spins of M are represented by the singly-occupied d-states (i.e.

Dysprosium magnesium silicate apatite featuring field and temperature stable slow magnetization relaxation.

Dy-Mg silicate DyMg(SiO)O has been prepared by high-temperature solid state reaction. It has an apatite type structure (6/) with the Dy atoms fully occupying the 6h site and being in random distribution with the Mg atoms at the 4f site. The compound reveals dual magnetization relaxation with widely varying contributions from fast (FR) and slow (SR) relaxation paths controlled by field and temperature.

Multiple slow relaxation of magnetization in Dy confined in the crystal matrix of rare-earth-calcium silicates with the apatite structure.

Apatite-type silicates Y7.75Dy0.25Ca2(SiO4)6O2 and Dy8Ca2(SiO4)6O2 were prepared by high-temperature solid state synthesis.

Synthesis and Magnetic Properties of the KCu(IO) Compound with [CuO] Chains.

The new quaternary iodate KCu(IO) has been prepared by hydrothermal synthesis. KCu(IO) crystallizes in the monoclinic space group 2/ with unit cell parameters = 9.8143(4) Å, = 8.

Superconductivity at 4.8 K and Violation of Pauli Limit in LaIRu Comprising Ru Honeycomb Layer.

We discovered superconductivity at 4.8 K in the hexagonal layered compound LaIRu comprising a triangular lattice of the La and a honeycomb lattice of the Ru atoms. First-principles calculations reveal a two-dimensional band structure made up of La 5 and Ru 4 electrons and formal oxidation states +1.

TbO in a calcium apatite matrix featuring a triple trigger-type relaxation of magnetization.

Tb for Ca substituted hydroxyapatite ceramic samples with composition Ca10-xTbx(PO4)6(OH1-x/2-δ)2, where x = 0.1, 0.5, were synthesized by solid-state reaction at 1300 °C in air, and their crystal structure, vibrational spectra, luminescence, and magnetic properties were studied.

Synthesis and Characterization of the Aurivillius Phase CoBiOF.

The new CoBiOF compound was synthesized by a hydrothermal method at 230 °C. Single-crystal X-ray diffraction data were used to determine the crystal structure. The compound is layered and belongs to the Aurivillius family of compounds.

On verdigris, part II: synthesis of the 2-1-5 phase, Cu(CHCOO)(OH)·5HO, by long-term crystallisation from aqueous solution at room temperature.

Long-term crystallisation from aqueous copper(ii)-acetate solution after the addition of ammonia at 25 °C led to the formation of a hitherto poorly characterised phase in the verdigris pigment system Cu(CH3COO)2-Cu(OH)2-H2O. Laboratory X-ray powder diffraction (XRPD) was successfully employed to solve the crystal structure. The structure solution reveals a phase composition of the Cu3(CH3COO)4(OH)2·5H2O ≡ 2-1-5 phase, which was also confirmed by thermal analysis.

Synthesis and Physical Properties of the Oxofluoride Cu(SeO)F.

Single crystals of the new compound Cu(SeO)F were successfully synthesized via a hydrothermal method, and the crystal structure was determined from single-crystal X-ray diffraction data. The compound crystallizes in the orthorhombic space group Pnma with the unit cell parameters a = 7.066(4) Å, b = 9.

Tunable Weyl and Dirac states in the nonsymmorphic compound CeSbTe.

Recent interest in topological semimetals has led to the proposal of many new topological phases that can be realized in real materials. Next to Dirac and Weyl systems, these include more exotic phases based on manifold band degeneracies in the bulk electronic structure. The exotic states in topological semimetals are usually protected by some sort of crystal symmetry, and the introduction of magnetic order can influence these states by breaking time-reversal symmetry.

Field-induced States and Excitations in the Quasicritical Spin-1/2 Chain Linarite.

The mineral linarite, PbCuSO_{4}(OH)_{2}, is a spin-1/2 chain with frustrating nearest-neighbor ferromagnetic and next-nearest-neighbor antiferromagnetic exchange interactions. Our inelastic neutron scattering experiments performed above the saturation field establish that the ratio between these exchanges is such that linarite is extremely close to the quantum critical point between spin-multipolar phases and the ferromagnetic state. We show that the predicted quantum multipolar phases are fragile and actually suppressed by a tiny orthorhombic exchange anisotropy and weak interchain interactions in favor of a dipolar fan phase.

On verdigris, part I: synthesis, crystal structure solution and characterisation of the 1-2-0 phase (Cu(CHCOO)(OH)).

Known synthesis approaches for basic copper(ii) acetates, the main components of historic verdrigis pigments were reinvestigated and revealed to be partially irreproducible. A modification of the reaction conditions led to the successful and reproducible synthesis of the 1-2-0 phase (Cu(CHCOO)(OH) = 1Cu(CHCOO)·2Cu(OH)·0HO). The phase composition was derived from elemental and thermal analysis and confirmed by the crystal structure solution using synchrotron X-ray powder diffraction (XRPD) data.

Structural and Magnetic Properties of the Trirutile-type 1D-Heisenberg Anti-Ferromagnet CuTaO.

We prepared trirutile-type polycrystalline samples of CuTaO by low-temperature decomposition of a Cu-Ta-oxalate precursor. Diffraction studies at room temperature identified a slight monoclinic distortion of the hitherto surmised tetragonal trirutile crystal structure. Detailed high-temperature X-ray and neutron powder diffraction investigations as well as Raman scattering spectroscopy revealed a structural phase transition at 503(3) K from the monoclinic structure to the tetragonal trirutile structure.

A Co-based single-molecule magnet confined in a barium phosphate apatite matrix with a high energy barrier for magnetization relaxation.

An apatite-type barium phosphate with a high content of cobalt ions in the trigonal channels features slow relaxation of magnetization with an energy barrier U of up to 387 cm, which is well above the values for all so far known d-metal based single-molecule magnets (SMMs).