The structural and compositional diversity of the
family of materials offers various magnetic and thermodynamic properties such as complex magnetic structure, vibronic bound states, heavy-fermions, ...valence fluctuations, metamagnetism, spin glass behavior, quantum criticality, and unconventional superconductivity. Here we present an overview of the crystal structures, crystal growth and magnetic properties of
compounds as well as a discussion of the relevant physics. The magnetic properties of several compounds of the
family still remain unexplored. The compounds with a complex magnetic structure could potentially host exotic topological phases. This review article may help explore exotic magnetic properties such as the vibron state and topological spin textures.
In quantum magnets, magnetic moments fluctuate heavily and are strongly entangled with each other, a fundamental distinction from classical magnetism. Here, with inelastic neutron scattering ...measurements, we probe the spin correlations of the honeycomb lattice quantum magnet YbCl
. A linear spin wave theory with a single Heisenberg interaction on the honeycomb lattice, including both transverse and longitudinal channels of the neutron response, reproduces all of the key features in the spectrum. In particular, we identify a Van Hove singularity, a clearly observable sharp feature within a continuum response. The demonstration of such a Van Hove singularity in a two-magnon continuum is important as a confirmation of broadly held notions of continua in quantum magnetism and additionally because analogous features in two-spinon continua could be used to distinguish quantum spin liquids from merely disordered systems. These results establish YbCl
as a benchmark material for quantum magnetism on the honeycomb lattice.
In actinide systems, the 5
electrons experience a uniquely delicate balance of effects and interactions having similar energy scales, which are often difficult to properly disentangle. This interplay ...of factors such as the dual nature of 5
-states, strong electronic correlations, and strong spin-orbit coupling results in electronically unusual and intriguing behavior such as multi-k antiferromagnetic ordering, multipolar ordering, Mott-physics, mixed valence configurations, and more. Despite the inherent allure of their exotic properties, the exploratory science of even the more basic, binary systems like the actinide oxides has been limited due to their toxicity, radioactivity, and reactivity. In this article, we provide an overview of the available synthesis techniques for selected binary actinide oxides, including the actinide dioxides, sesquioxides, and a selection of higher oxides. For these oxides, we also review and evaluate the current state of knowledge of their crystal structures and magnetic properties. In many aspects, substantial knowledge gaps exist in the current body of research on actinide oxides related to understanding their electronic ground states. Bridging these gaps is vital for improving not only a fundamental understanding of these systems but also of future nuclear technologies. To this end, we note the experimental techniques and necessary future investigations which may aid in better elucidating the nature of these fascinating systems.
Optoelectronic devices based on lanthanide-containing materials are an emergent area of research due to imminent interest in a new generation of diode materials, optical and magnetic sensors, and ...ratiometric thermometers. Tailoring material properties through the employment of photo- or thermochromic moieties is a powerful approach that requires a deep fundamental understanding of possible cooperativity between lanthanide-based metal centers and integrated switchable units. In this work, we probe this concept through the synthesis, structural analysis, and spectroscopic characterization of novel photochromic lanthanide-based metal-organic materials containing noncoordinatively integrated photoresponsive 4,4'-azopyridine between lanthanide-based metal centers. As a result, a photophysical material response tailored on demand through the incorporation of photochromic compounds within a rigid matrix was investigated. The comprehensive analysis of photoresponsive metal-organic materials includes single-crystal X-ray diffraction and diffuse reflectance spectroscopic studies that provide guiding principles necessary for understanding photochromic unit-lanthanide-based metal-organic framework (MOF) cooperativity. Furthermore, steady-state and time-resolved diffuse reflectance spectroscopic studies revealed a rapid rate of photoresponsive moiety attenuation upon its integration within the rigid matrix of lanthanide-based MOFs in comparison with that in solution, highlighting a unique role and synergy that occurred between stimuli-responsive moieties and the lanthanide-based MOF platform, allowing for tunability and control of material photoisomerization kinetics.Optoelectronic devices based on lanthanide-containing materials are an emergent area of research due to imminent interest in a new generation of diode materials, optical and magnetic sensors, and ratiometric thermometers. Tailoring material properties through the employment of photo- or thermochromic moieties is a powerful approach that requires a deep fundamental understanding of possible cooperativity between lanthanide-based metal centers and integrated switchable units. In this work, we probe this concept through the synthesis, structural analysis, and spectroscopic characterization of novel photochromic lanthanide-based metal-organic materials containing noncoordinatively integrated photoresponsive 4,4'-azopyridine between lanthanide-based metal centers. As a result, a photophysical material response tailored on demand through the incorporation of photochromic compounds within a rigid matrix was investigated. The comprehensive analysis of photoresponsive metal-organic materials includes single-crystal X-ray diffraction and diffuse reflectance spectroscopic studies that provide guiding principles necessary for understanding photochromic unit-lanthanide-based metal-organic framework (MOF) cooperativity. Furthermore, steady-state and time-resolved diffuse reflectance spectroscopic studies revealed a rapid rate of photoresponsive moiety attenuation upon its integration within the rigid matrix of lanthanide-based MOFs in comparison with that in solution, highlighting a unique role and synergy that occurred between stimuli-responsive moieties and the lanthanide-based MOF platform, allowing for tunability and control of material photoisomerization kinetics.
Compounds adopting the Yb3Rh4Sn13 structure type have drawn attention because of the revelation of exotic states such as heavy fermion behavior, superconductivity, charge density wave, and quantum ...critical behavior. The prototypical structure has historically been modeled with a primitive cubic space group, Pm3&cmb.macr; n; however, structural studies have led to the realization of disordered atomic sites, requiring lower symmetry models. We will review the low symmetry models required to describe the structural distortions in the related Yb3Rh4Sn13 structure type. In addition, we present the structure determination of a new analogue, Lu3Ir4Ge13, which adopts a new structural model in I41/amd.
Novel near infrared-absorbing iron oxide-gold core-shell nanoparticles in pin shapes were synthesized. The nanopins are superparamagnetic, with 35-fold better surface enhanced Raman scattering ...activities than the conventional core-shell nanospheres and 50-fold greater photothermal properties than solid gold nanorods. The nanoparticles will have important impact on medical imaging, molecular diagnostics and disease treatment.
Single crystals of (Lu1−xY bx)3Rh4Ge13 were characterized by magnetization, specific heat, and electrical resistivity measurements. Doping Yb into the non-magnetic Lu3Rh4Ge13 compound tunes this ...cubic system’s properties from a superconductor with disordered metal normal state (x < 0.05) to a Kondo for 0.05 ≤ x ≤0.2 and intermediate valence at the highest Yb concentrations. The evidence for intermediate Yb valence comes from a broad maximum in the magnetic susceptibility and X-ray photoelectron spectroscopy. Furthermore, the resistivity displays a local maximum at finite temperatures at intermediate compositions x, followed by apparent metallic behavior closest to the Yb end compound in the series.
We study the correlated quantum magnet YbCl3 with neutron scattering, magnetic susceptibility, and heat capacity measurements. The crystal field Hamiltonian is determined through simultaneous ...refinements of the inelastic neutron scattering and magnetization data. The ground-state doublet is well isolated from the other crystal field levels and results in an effective spin-1/2 system with local easy plane anisotropy at low temperature. Cold neutron spectroscopy shows low-energy excitations peaked at 0.5 meV that are consistent with nearest-neighbor antiferromagnetic correlations.
We show that Ce- and Yb-based Kondo-lattice ferromagnets order mainly along the magnetically hard direction of the ground-state Kramers doublet determined by crystalline electric field. Here, we ...argue that this peculiar phenomenon, that was believed to be rare, is instead the standard case. Moreover, it seems to be independent on the Curie temperature TC, crystalline structure, size of the ordered moment, and type of ground-state wave function. On the other hand, all these systems show the Kondo coherence maximum in the temperature dependence of the resistivity just above TC, which indicates a Kondo temperature of a few degrees Kelvin. An important role of fluctuations is indicated by the non-mean-field-like transition in specific heat measurements as well as by the suppression of this effect by a strong Ising-like anisotropy. We discuss possible theoretical scenarios.
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