Interplay between Local Moment and Itinerant Magnetism in the Layered Metallic Antiferromagnet TaFe1.14Te3.

Two-dimensional antiferromagnets have garnered considerable interest for the next generation of functional spintronics. However, many bulk materials from which two-dimensional antiferromagnets are isolated are limited by their air sensitivity, low ordering temperatures, and insulating transport properties. TaFe1+yTe3 aims to address these challenges with increased air stability, metallic transport, and robust antiferromagnetism. Here, we synthesize TaFe1+yTe3 (y = 0.14), identify its structural, magnetic, and electronic properties, and elucidate the relationships between them. Axial-dependent high-field magnetization measurements on TaFe1.14Te3 reveal saturation magnetic fields ranging between 27 and 30 T with saturation magnetic moments of 2.05-2.12 µB. Magnetotransport measurements confirm that TaFe1.14Te3 is metallic with strong coupling between magnetic order and electronic transport. Angle-resolved photoemission spectroscopy measurements across the magnetic transition uncover a complex interplay between itinerant electrons and local magnetic moments that drives the magnetic transition. We demonstrate the ability to isolate few-layer sheets of TaFe1.14Te3, establishing TaFe1.14Te3 as a potential platform for two-dimensional spintronics.

Relations between bedtime parenting behaviors and temperament across 14 cultures.

Objectives: The present study examined parental sleep-supporting practices during toddlerhood in relation to temperament across 14 cultures. We hypothesized that passive sleep-supporting techniques (e.g., talking, cuddling), but not active techniques (e.g., walking, doing an activity together), would be associated with less challenging temperament profiles: higher Surgency (SUR) and Effortful Control (EC) and lower Negative Emotionality (NE), with fine-grained dimensions exhibiting relationships consistent with their overarching factors (e.g., parallel passive sleep-supporting approach effects for dimensions of NE). Methods: Caregivers (N = 841) across 14 cultures (M = 61 families per site) reported toddler (between 17 and 40 months of age; 52% male) temperament and sleep-supporting activities. Utilizing linear multilevel regression models and group-mean centering procedures, we assessed the role of between- and within-cultural variance in sleep-supporting practices in relation to temperament. Results: Both within-and between-culture differences in passive sleep-supporting techniques were associated with temperament attributes, (e.g., lower NE at the between-culture level; higher within-culture EC). For active techniques only within-culture effects were significant (e.g., demonstrating a positive association with NE). Adding sleep-supporting behaviors to the regression models accounted for significantly more between-culture temperament variance than child age and gender alone. Conclusion: Hypotheses were largely supported. Findings suggest parental sleep practices could be potential targets for interventions to mitigate risk posed by challenging temperament profiles (e.g., reducing active techniques that are associated with greater distress proneness and NE).

Broad-band Chiral Absorbance of Visible Light.

The amplification of chiral absorbance and emission is a primary figure of merit for the design of chiral chromophores. However, for dyes to be practically relevant in chiroptical applications, they must also absorb and/or emit chiral light over broad wavelength ranges. We investigate the interplay between molecular symmetry and broad-band chiral absorbance in a series of [6]helicenes. We find that an asymmetric [6]helicene containing two distinct chromophores absorbs chiral light across a much wider wavelength range than the symmetric [6]helicenes investigated here. Chemically reducing the helicenes shifts the absorption edge of the ECD spectra into the near-infrared wavelength range while preserving broad chiral absorption, producing a [6]helicene that absorbs a single handedness of light across the entire visible wavelength range.

Site-Selective Surface Modification of 2D Superatomic Re6Se8.

Coating two-dimensional (2D) materials with molecules bearing tunable properties imparts their surfaces with functionalities for applications in sensing, nanoelectronics, nanofabrication, and electrochemistry. Here, we report a method for the site-selective surface functionalization of 2D superatomic Re6Se8Cl2 monolayers. First, we activate bulk layered Re6Se8Cl2 by intercalating lithium and then exfoliate the intercalation compound Li2Re6Se8Cl2 in N-methylformamide (NMF). Heating the resulting solution eliminates LiCl to produce monolayer Re6Se8(NMF)2-x (x ≈ 0.4) as high-quality nanosheets. The unpaired electrons on each cluster in Re6Se8(NMF)2-x enable covalent surface functionalization through radical-based chemistry. We demonstrate this to produce four previously unknown surface-functionalized 2D superatomic materials: Re6Se8I2, Re6Se8(SPh)2, Re6Se8(SPhNH2)2, and Re6Se8(SC16H33)2. Transmission electron microscopy, chemical analysis, and vibrational spectroscopy reveal that the in-plane structure of the 2D Re6Se8 material is preserved through surface functionalization. We find that the incoming groups control the density of vacancy defects and the solubility of the 2D material. This approach will find utility in installing a broad array of chemical functionalities on the surface of 2D superatomic materials as a means to systematically tune their physical properties, chemical reactivity, and solution processability.

Links between television exposure and toddler dysregulation: Does culture matter?

Television exposure in early childhood has increased, with concerns raised regarding adverse effects on social-emotional development, and emerging self-regulation in particular. The present study addressed television exposure (i.e., amount of time watching TV) and its associations with toddler behavioral/emotional dysregulation, examining potential differences across 14 cultures. The sample consisted of an average of 60 toddlers from each of the 14 countries from the Joint Effort Toddler Temperament Consortium (JETTC; Gartstein & Putnam, 2018). Analyses were conducted relying on the multi-level modeling framework (MLM), accounting for between- and within-culture variability, and examining the extent to which TV exposure contributions were universal vs. variable across sites. Effects of time watching TV were evaluated in relation to temperament reactivity and regulation, as well as measures of emotional reactivity, attention difficulties, and aggression. Results indicated that more time spent watching TV was associated with higher ratings on Negative Emotionality, emotional reactivity, aggression, and attention problems, as well as lower levels of soothability. However, links between TV exposure and both attention problems and soothability varied significantly between cultures. Taken together, results demonstrate that increased time spent watching television was generally associated with dysregulation, although effects were not consistently uniform, but rather varied as a function of culturally-dependent contextual factors.

Polytypism, Anisotropic Transport, and Weyl Nodes in the van der Waals Metal TaFeTe4.

Layered van der Waals (vdW) materials belonging to the MM'Te4 structure class have recently received intense attention due to their ability to host exotic electronic transport phenomena, such as in-plane transport anisotropy, Weyl nodes, and superconductivity. Here we report two new vdW materials with strongly anisotropic in-plane structures featuring stripes of metallic TaTe2 and semiconducting FeTe2, α-TaFeTe4 and ß-TaFeTe4. We find that the structure of α-TaFeTe4 produces strongly anisotropic in-plane electronic transport (anisotropy ratio of up to 250%), outcompeting all other vdW metals, and demonstrate that it can be mechanically exfoliated to the two-dimensional (2D) limit. We also explore the possibility that broken inversion symmetry in ß-TaFeTe4 produces Weyl points in the electronic band structure. Eight Weyl nodes slightly below the Fermi energy are computationally identified for ß-TaFeTe4, indicating they may contribute to the transport behavior of this polytype. These findings identify the TaFeTe4 polytypes as an ideal platform for investigation of 2D transport anisotropy and chiral charge transport as a result of broken symmetry.

From Thorium to Plutonium: Trends in Actinide(IV) Chloride Structural Chemistry.

A series of eighteen tetravalent actinide (An = Th, U, Pu) compounds were synthesized from acidic aqueous solutions containing thorium, uranium, or plutonium and a series of protonated nitrogen heterocycles. The compounds were characterized using Raman, IR, and optical absorption spectroscopies. The structures were determined using single-crystal X-ray diffraction and found to consist of [An(H2O)xCly]4-y (x = 4-7 and y = 2-4) or AnCl62- molecular units. Breaks in the structural chemistry of the early actinides were observed, with Th adopting exclusively Th-aquo-chloro species and Pu forming only PuCl62-; U crystallized as both U-aquo-chloro and UCl62-. The relationship between the solid-state structural units and the solution species was interrogated using UV-vis-near-IR absorption spectroscopy. A comparison of the solution and solid-state spectra suggested that, although prevalent in the solid state, particularly for U and Pu, AnCl62- does not exist to an appreciable extent in the reaction solution. Despite the identification of U-aquo-chloro species in solution, there are limited reports of these complexes in the solid state. Isolation of these unique actinide(IV) chlorides as reported in this work may point to the importance of nonbonding interactions in the stabilization and precipitation of AnIV structural units.

Monomeric and Trimeric Thorium Chlorides Isolated from Acidic Aqueous Solution.

Two thorium(IV) compounds, [Th(H2O)4Cl4]·2(HPy·Cl) (1) and (HPy)3[Th3(H2O)2Cl10(OH)5]·4(HPy·Cl) (2) (HPy = pyridinium), were isolated from acidic aqueous solution. The compounds were synthesized at room temperature and subsequently characterized using single crystal X-ray diffraction along with Raman and IR spectroscopies. Whereas compound 1 is built from discrete mononuclear Th(H2O)4Cl4 units, compound 2 consists of a novel hydroxo-bridged trimeric [Th3(OH)5]7+ core. Such species are largely absent from discussions of Th solution and solid-state chemistry and their isolation may be attributed to outer coordination sphere interactions that help stabilize the structural units; extensive hydrogen bonding and π-π stacking interactions are present in 1 and 2. Density functional theory calculations were performed to predict the respective vibrational frequencies of the structural units, and their relative stability was predicted at the correlated molecular theory level. Small-angle X-ray scattering analysis of [Th3(OH)5]7+ in water indicates that the trimeric structural unit remains intact and that it is indeed an important species that necessitates consideration in geochemical models and for design of Th materials from water.

Photoluminescence of Visible and NIR-Emitting Lanthanide-Doped Bismuth-Organic Materials.

A bismuth-organic compound containing 2,2':6'2"-terpyridine (terpy) and 2-thiophenecarboxylate (TC), of the general formula (terpy)Bi(κ2 -TC)3 ⋅0.47 H2 O (BiOM-1), has been synthesized under hydrothermal conditions. Addition of a lanthanide nitrate solution to the reaction mixture led to statistical replacement of the bismuth centers, and yielded isomorphous lanthanide containing compounds Bi1-x Lnx OM-1 (Ln=Nd, Sm, Eu, Tb, Dy, Er, and Yb) that showed bismuth and/or ligand sensitized lanthanide-centered emission, and the first example of NIR emission from a lanthanide doped BiOM. The structure was determined by single-crystal X-ray diffraction, and the level and uniformity of lanthanide ion incorporation into the bismuth host was determined by ICP-OES and electron microprobe analysis. For the visible emitters, lifetime data and quantum yields are presented. A high efficiency of sensitization was calculated for the europium analog (50.1 %), showing significant improvement over previously reported europium thiophenecarboxylates. These novel materials may provide strategies to address concerns over the long-term sustainability of the rare earth elements, especially relating to optical devices.