Spectroscopic signatures and origin of hidden order in BaMgReO.

Clarifying the underlying mechanisms that govern ordering transitions in condensed matter systems is crucial for comprehending emergent properties and phenomena. While transitions are often classified as electronically driven or lattice-driven, we present a departure from this conventional picture in the case of the double perovskite BaMgReO. Leveraging resonant and non-resonant elastic x-ray scattering techniques, we unveil the simultaneous ordering of structural distortions and charge quadrupoles at a critical temperature of T ~ 33 K.

Dynamic Jahn-Teller effect in the strong spin-orbit coupling regime.

Exotic quantum phases, arising from a complex interplay of charge, spin, lattice and orbital degrees of freedom, are of immense interest to a wide research community. A well-known example of such an entangled behavior is the Jahn-Teller effect, where the lifting of orbital degeneracy proceeds through lattice distortions. Here we demonstrate that a highly-symmetrical 5d double perovskite BaMgReO, comprising a 3D array of isolated ReO octahedra, represents a rare example of a dynamic Jahn-Teller system in the strong spin-orbit coupling regime.

Spin-Orbit-Lattice Entangled State in A_{2}MgReO_{6} (A=Ca, Sr, Ba) Revealed by Resonant Inelastic X-Ray Scattering.

The 5d^{1} ordered double perovskites present an exotic playground for studying novel multipolar physics due to large spin-orbit coupling. We present Re L_{3} edge resonant inelastic x-ray scattering (RIXS) results that reveal the presence of the dynamic Jahn-Teller effect in the A_{2}MgReO_{6} (A=Ca, Sr, Ba) family of 5d^{1} double perovskites. The spin-orbit excitations in these materials show a strongly asymmetric line shape and exhibit substantial temperature dependence, indicating that they are dressed with lattice vibrations.

Pinalites: Optical Properties and Quantum Magnetism of Heteroanionic AMOX Compounds.

Heteroanionic compounds, which contain two or more types of anions, have emerged as a promising class of materials with diverse properties and functionalities. In this paper, I review the experimental findings on CaReOCl and related compounds that exhibit remarkable pleochroism and novel quantum magnetism. I discuss how the heteroanionic coordination affects the optical and magnetic properties by modulating the d-orbital states of the transition metal ions.

Superconductivity in High-Entropy Antimonide MPtSb (M = Equimolar Ru, Rh, Pd, and Ir).

The high-entropy concept was applied to the synthesis of transition-metal antimonides, MPtSb (M = equimolar Ru, Rh, Pd, and Ir). High-entropy antimonide samples crystallized in a pseudo-hexagonal NiAs-type crystal structure with a 6/ space group were successfully synthesized through a conventional solid-state reaction and subsequent quenching. A detailed investigation of the composition and equilibration conditions confirmed the reversible phase transition between a multiphase state at low temperature and an entropy-driven single-phase solid solution at high temperatures.

Fermi surface and light quasi particles in hourglass nodal chain metal-ReO.

Quantum oscillations (QOs) in magnetic torque and electrical resistivity were measured to investigate the electronic structure of-ReO, a candidate hourglass nodal chain (NC) metal (Dirac loop chain metal). All the de Haas-van Alphen oscillation branches measured at 30 mK in magnetic fields of up to 17.5 T were consistent with first-principles calculations predicting four Fermi surfaces (FSs).

Crystallization of heavy fermions via epitaxial strain in spinel LiVO thin film.

The mixed-valent spinel LiVO is known as the first oxide heavy-fermion system. There is a general consensus that a subtle interplay of charge, spin, and orbital degrees of freedom of correlated electrons plays a crucial role in the enhancement of quasi-particle mass, but the specific mechanism has remained yet elusive. A charge-ordering (CO) instability of V and V ions that is geometrically frustrated by the V pyrochlore sublattice from forming a long-range CO down to = 0 K has been proposed as a prime candidate for the mechanism.

Mechanism of Reductive Fluorination by PTFE-Decomposition Fluorocarbon Gases for WO.

Reductive fluorination, which entails the substitution of O from oxide compounds with F from fluoropolymers, is considered a practical approach for preparing transition-metal oxyfluorides. However, the current understanding of the fundamental reaction paths remains limited due to the analytical complexities posed by high-temperature reactions in glassware. Therefore, to expand this knowledgebase, this study investigates the reaction mechanisms behind the reductive fluorination of WO using polytetrafluoroethylene (PTFE) in an Ni reactor.

Successive phase transitions of the spin-orbit-coupled metal CdReOprobed by high-resolution synchrotron x-ray diffraction.

The 5pyrochlore oxide superconductor CdReO(CRO) has attracted significant interest as a spin-orbit-coupled metal (SOCM) that spontaneously undergoes a phase transition to an odd-parity multipole phase by breaking the spatial inversion symmetry due to the Fermi liquid instability caused by strong spin-orbit coupling. Despite the significance of structural information during the transition, previous experimental results regarding lattice deformation have been elusive. We have conducted ultra-high resolution synchrotron radiation x-ray diffraction experiments on a high-quality CRO single crystal.

Characterization of the charge transfer luminescence of the [WO] octahedron in CaWO and the [WO] square pyramid in CaWOCl.

Charge transfer (CT) luminescence of different types of polyhedra, [WO] in CaWOCl and [WO] in CaWO, is characterized by spectroscopic experiments and calculations. According to the geometry optimization, W ions form five-fold [WO] square pyramids in CaWOCl because of a large interatomic distance between W and Cl of 3.266 Å.

Linear Trimer Molecule Formation by Three-Center-Four-Electron Bonding in a Crystalline Solid RuP.

Some inorganic solids undergo phase transitions that result in the formation of "molecules" in their crystalline frameworks, which are frequently accompanied by dramatic changes in physical properties; the metal-insulator transition (MIT) in vanadium dioxide, for instance, is accompanied by the formation of dimer molecules with conventional two-center-two-electron bonding. We have discovered the creation of a linear ruthenium trimer with atypical three-center-four-electron bonding in ruthenium monophosphide at its MIT. Our detailed structural investigation and electronic structure calculations reveal that charge transfer from polymerized phosphorous to ruthenium automatically tunes the electron density to precisely four per trimer at the MIT, with all conduction electrons present at high temperatures being trapped by the trimer's molecular orbitals at low temperatures.

Pyrochlore oxide HgOsOon verge of metal-insulator boundary.

Semimetallic osmium pyrochlore oxide CdOsOundergoes a magnetic transition to an all-in-all-out (AIAO)-type order at 227 K, followed by a crossover to an AIAO insulator at around 210 K. Here, we studied the isostructural and isoelectronic compound HgOsOthrough thermodynamic measurements, muon spin rotation (μSR) spectroscopy and neutron diffraction experiments. A similar magnetic transition, probably to an AIAO-type order, was observed at 88 K, while the resistivity showed a decrease at the transition and remained metallic down to 2 K.

Possible quadrupole order in tetragonal BaCdReOand chemical trend in the ground states of 5double perovskites.

The synthesis and physical properties of the double perovskite (DP) compound BaCdReOwith the 5electronic configuration are reported. Three successive phases originating from a spin-orbit-entangled= 3/2 state, confirmed by a reduced effective magnetic moment of 0.72 , were observed upon cooling.

Anisotropic Triangular Lattice Realized in Rhenium Oxychlorides AReOCl (A = Ba, Sr).

We report the synthesis, crystal structure, and magnetic properties of the two new quantum antiferromagnets AReOCl (A = Sr, Ba). The crystal structure is isostructural with the mineral pinalite PbWOCl, in which the Re ion is square pyramidally coordinated by five oxide atoms and forms an anisotropic triangular lattice (ATL) made of = 1/2 spins. The magnetic interactions and ' in the ATL are estimated from magnetic susceptibilities to be 19.

NaPtSi: A Non-Centrosymmetric Superconductor Having Rattling Na Atoms in the Tunnel Framework Structure.

Single crystals of a novel Na-Pt-Si ternary compound, NaPtSi, were synthesized by heating the constituent elements at 1423 K. It crystallizes in a non-centrosymmetric trigonal structure of space group 32 ( = 3) with lattice constants of = 10.1536(3) Å and = 10.

Synthesis of anti-perovskite-type carbides and nitrides from metal oxides and melamine.

Four anti-perovskite-type compounds, ZnNNi, ZnCNi, SnNCo, and SnCCo, are synthesised through reactions between metal oxides and organic compound melamine (CHN). ZnNNi and ZnCNi are selectively synthesised by choosing different reaction temperatures and nominal oxide-to-melamine ratios. SnNCo is synthesised for the first time by this melamine method.

Spontaneous formation of zigzag chains at the metal-insulator transition in the β-pyrochlore CsW2O6.

A paramagnetic metal to nonmagnetic insulator transition at T(MIT)=210 K is reported for the β-pyrochlore oxide CsW(2)O(6), accompanied by a first order structural transition that creates <110> oriented chains in the pyrochlore lattice. Comparison of CsW(2)O(6), which has 1 electron per 2 W sites, to the fully d(0) analog CsTaWO(6) shows that the transitions are electronically driven. Corefinement of high resolution synchrotron x-ray and neutron diffraction data shows that the structural distortion that creates the W chains cannot be attributed to simple charge or orbital ordering.

Synthesis, structure, and magnetic studies of manganese-oxygen clusters of reduced coordination number, featuring an unchelated, 5-coordinate octanuclear manganese cluster with water-derived oxo ligands.

The synthesis of reduced coordination (less than 6), unchelated manganese oxygen cluster systems is described. Addition of phenols to Mn(NR(2))(2) (R = SiMe(3)) results in protolytic amide ligand replacement, and represents the primary entry into the described chemistry. Addition of PhOH to Mn(NR(2))(2) results in the formation of the heteroleptic dimer Mn(2)(μ-OPh)(2)(NR(2))(2)(THF)(2) (1).