This article reviews the physics of multipolar interactions and order in $f$-electron systems, using actinide dioxides as a paradigm. In past few years, these apparently simple cubic compounds have been studied intensively, many new phenomena discovered. Here experimental results are discussed together with current theoretical understanding interactions.

The crystallographic structure and the magnetic order of distorted perovskite ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CoO}}_{3}$ $(0.10<~x<~0.30)$ has been studied by neutron diffraction, high-resolution electron microscopy, magnetic-susceptibility measurements. results give direct evidence for an inhomogeneous distribution ${\mathrm{Sr}}^{2+}$ ions segregation material into hole-rich ferromagnetic regions a hole-poor semiconducting matrix at lower values x. holes...

Neutron spectroscopy has been used to observe transitions between the energy levels for 21 different orientations of $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}10$ spin ground state an octanuclear iron molecular cluster $({\mathrm{Fe}}_{8})$ exhibiting quantum tunneling magnetization. The results obtained on nondeuterated samples provide first direct measurement zero-field splitting in a large nanomagnet. A reliable and accurate determination composition cluster's wave functions...

Selective memory: Using actinides in designing molecular nanomagnets could provide better performance and higher anisotropy barriers, owing to the peculiar properties of 5f electron shell. Neptunocene is found display an open magnetic hysteresis cycle at low temperatures (see picture), interaction with hyperfine degrees freedom determines whether relaxation fast or slow a given field value.

Reducing the irreducible: Incorporation of a lanthanide cation into vacant coordination pocket uranyl Pacman complex results in single electron reduction to form stable pentavalent uranyl–rare-earth complexes with uranyl–oxo–rare-earth bonds (see scheme; py=pyridine, R=SiMe3). Detailed facts importance specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted by authors. Please note: The publisher...

The heterobimetallic complexes [{UO2Ln(py)2(L)}2], combining a singly reduced uranyl cation and rare-earth trication in binucleating polypyrrole Schiff-base macrocycle (Pacman) bridged through oxo-group, have been prepared for Ln = Sc, Y, Ce, Sm, Eu, Gd, Dy, Er, Yb, Lu. These compounds are formed by the single-electron reduction of Pacman complex [UO2(py)(H2L)] Ln(III)(A)3 (A N(SiMe3)2, OC6H3Bu(t)2-2,6) via homolysis Ln-A bond. dimeric mutual exo-oxo coordination but can be cleaved to form...

Abstract Improving the performance of molecular qubits is a fundamental milestone towards unleashing power magnetism in second quantum revolution. Taming spin relaxation and decoherence due to vibrations crucial reach this milestone, but hindered by our lack understanding on nature their coupling spins. Here we propose synergistic approach study prototypical qubit. It combines inelastic X-ray scattering measure phonon dispersions along main symmetry directions crystal dynamics simulations...

We report the results of resonant x-ray scattering experiments performed at Np ${M}_{4,5}$ edges in $\mathrm{N}\mathrm{p}{\mathrm{O}}_{\mathrm{2}}$. Below ${T}_{0}=25\text{ }\text{ }\mathrm{K}$, development long-range order electric quadrupoles is revealed by growth superlattice Bragg peaks. The polarization and azimuthal dependence intensity peaks are well reproduced assuming anisotropic tensor susceptibility from a triple-$\stackrel{\ensuremath{\rightarrow}}{q}$ longitudinal...

High-resolution, high-energy-transfer, inelastic neutron scattering has been used to explore the crystal-field (CF) excitations in ${\mathrm{UO}}_{2}$. As all dipole-allowed transitions within free-ion ground manifold have identified, observations provide a complete determination of potential and 5f-electron eigenstates. The fourth- sixth-degree CF parameters are ${V}_{4}$=-123 meV ${V}_{6}$=26.5 meV. In spite strength CF, state is accurately given by intermediate-coupling approximation with...

Exchange integrals and single-ion anisotropy parameters of a ring-shaped molecular cluster, comprising eight chromium(III) ions $(s=3/2)$ were determined by inelastic neutron scattering. Effects due to the mixing different spin multiplets have been considered. Such effects proved be important correctly reproduce relative intensity magnetic excitations in spectra. Evidence decreasing lifetimes with increasing energy excited states was found. The microscopic picture emerging from spectroscopy...

We report direct experimental evidence for long-range antiferro ordering of the electric-quadrupole moments on U ions. Resonant x-ray scattering experiments at uranium ${M}_{4}$ absorption edge show a characteristic dependence in integrated intensity upon rotation crystal around vector. Although quadrupolar order dioxide was advocated already 1960s, no this phenomenon provided until now. conclude with possible model to explain phase diagram solid solutions $\mathrm{U}{\mathrm{O}}_{2}$ and...

Abstract Single‐chain magnets (SCMs) are materials composed of magnetically isolated one‐dimensional (1D) units exhibiting slow relaxation magnetization. The occurrence SCM behavior requires the fulfillment stringent conditions for exchange and anisotropy interactions. Herein, we report synthesis, structure, magnetic characterization first actinide‐containing SCM. 5f–3d heterometallic 1D chains [{[UO 2 (salen)(py)][M(py) 4 ](NO 3 )}] n , (M=Cd ( 1 ) M=Mn ); py=pyridine) assembled trough...

Lanthanide-like: X-ray diffraction and density functional theory studies show that [An(H2O)9]3+ ions of the actinides U3+–Cf3+ in crystals their triflate salts have same structure electrostatic bonding as lanthanide counterparts La3+–Eu3+. Moreover, nine-coordinate geometry is essentially preserved solution for lighter elements (see picture). In recent years there has been considerable progress understanding chemistry low-valent synthesis techniques compounds. A significant number new...

Thin films of the elusive intermediate uranium oxide U2O5 have been prepared by exposing UO3 precursor multilayers to atomic hydrogen. Electron photoemission spectra measured about 4f core-level doublet contain sharp satellites separated 7.9(1) eV from main lines, whilst characteristics U(IV) and U(VI) oxidation states, expected respectively at 6.9(1) 9.7(1) are absent. This shows that ions in a pure pentavalent state, contrast previous investigations binary oxides claiming U(V) occurs only...

The actinides comprise a 15-member group of metallic radioactive elements occupying the bottom row periodic table. Electron localization accompanied by formation large magnetic moments due to strong Coulomb repulsion is balanced hybridization with neighboring-atom electronic states. This promotes an opposite tendency toward itinerancy and emergence complex behavior. review shows how x-ray synchrotron radiation techniques provide variety powerful tools unravel complexity actinide materials....

Inelastic neutron scattering with polarization analysis has been used to study the evolution of magnetic response across antiferromagnetic paramagnetic transition in a single crystal uranium dioxide ${(T}_{N}=30.8 \mathrm{K})$. The spin-wave dispersion curves have determined at 16 K by measuring spin-flip channel cross section along principal crystallographic directions. Evidence magnon-phonon interactions $(0,0,\ensuremath{\xi})$ direction is given splitting lowest branch, and Q dependence...

MnAs exhibits a first-order phase transition from ferromagnetic, high-spin metal hexagonal to paramagnetic, lower-spin insulator orthorhombic at ${T}_{C}=313\text{ }\mathrm{K}$. Here, we report the results of neutron diffraction experiments showing that an external magnetic field, $B$, stabilizes above ${T}_{C}$. The transformation is reversible and constitutes first demonstration bond-breaking induced by field. field-induced accompanied enhanced magnetoresistance about $17%$ $310\text{...

Using inelastic neutron scattering and applied fields up to 11.4 T, we have studied the spin dynamics of Cr7Ni antiferromagnetic ring in energy window 0.05-1.6 meV. We demonstrate that external magnetic field induces an avoided crossing (anticrossing) between levels with different total-spin quantum numbers. This corresponds oscillations total each molecule. The character observed excitation dependence its linewidth indicate molecular spins oscillate coherently for a significant number...

Inelastic neutron scattering has been applied to the study of spin dynamics Cr-based antiferromagnetic octanuclear rings where a finite total ground state is obtained by substituting one ${\mathrm{Cr}}^{3+}$ ion $(s=3∕2)$ with $\mathrm{Zn}\phantom{\rule{0.3em}{0ex}}(s=0)$, $\mathrm{Mn}\phantom{\rule{0.3em}{0ex}}(s=5∕2)$, or $\mathrm{Ni}\phantom{\rule{0.3em}{0ex}}(s=1)$ dications. Energy and intensity measurements for several intramultiplet intermultiplet magnetic excitations allow us...

${{\mathrm{Np}}^{\mathrm{VI}}{\mathrm{O}}_{2}{\mathrm{Cl}}_{2}}{{\mathrm{Np}}^{\mathrm{V}}{\mathrm{O}}_{2}\mathrm{Cl}(\mathrm{thf}{)}_{3}{}}_{2}$ is the first studied example of a polymetallic transuranic complex displaying both slow relaxation magnetization and effective superexchange interactions between $5f$ centers. The coupling constant for ${\mathrm{Np}}^{\mathrm{V}}\mathrm{\text{\ensuremath{-}}}{\mathrm{Np}}^{\mathrm{VI}}$ pairs 10.8 K, more than 1 order magnitude larger common values...

A high energy resolution x-ray absorption near-edge structure (XANES) spectroscopy study on ${\text{U}}^{4+}$ $({\text{UO}}_{2})$, ${\text{U}}^{5+}$ $([{\text{UO}}_{2}{\text{Py}}_{5}][{\text{KI}}_{2}{\text{Py}}_{2}])$, and ${\text{U}}^{6+}$ $[{\text{UO}}_{2}{({\text{NO}}_{3})}_{2}{({\text{H}}_{2}\text{O})}_{6}]$ demonstrates the potential of this experimental technique for qualitative/semiqualitative quantitative actinide speciation investigations. We observe a pre-edge feature with...