Thermal Characterization of Ferroelectric AlBN for Nonvolatile Memory.

Boron (B)-substituted wurtzite AlN (AlBN) is a recently discovered wurtzite ferroelectric material that offers several advantages over ferroelectric HfZrO and PbZrTiO. Such benefits include a relatively low growth temperature as well as a thermally stable, and thickness-stable ferroelectric polarization; these factors are promising for the development of ferroelectric nonvolatile random-access memory (FeRAM) that are CMOS-compatible, scalable, and reliable for storing data in harsh environments. However, wurtzite ferroelectric materials may undergo exacerbated self-heating upon polarization switching relative to other ferroelectric materials; the larger energy loss is anticipated due to the higher coercive field and remanent polarization.

Unconventional Spectral Gaps Induced by Charge Density Waves in the Weyl Semimetal (TaSe)I.

Coupling Weyl quasiparticles and charge density waves (CDWs) can lead to fascinating band renormalization and many-body effects beyond band folding and Peierls gaps. For the quasi-one-dimensional chiral compound (TaSe)I with an incommensurate CDW transition at = 263 K, photoemission mappings thus far are intriguing due to suppressed emission near the Fermi level. Models for this unconventional behavior include axion insulator phases, correlation pseudogaps, polaron subbands, bipolaron bound states, etc.

Spin-resolved topology and partial axion angles in three-dimensional insulators.

Symmetry-protected topological crystalline insulators (TCIs) have primarily been characterized by their gapless boundary states. However, in time-reversal- ([Formula: see text]-) invariant (helical) 3D TCIs-termed higher-order TCIs (HOTIs)-the boundary signatures can manifest as a sample-dependent network of 1D hinge states. We here introduce nested spin-resolved Wilson loops and layer constructions as tools to characterize the intrinsic bulk topological properties of spinful 3D insulators.

Design Rules, Accurate Enthalpy Prediction, and Synthesis of Stoichiometric Eu Quantum Memory Candidates.

Stoichiometric Eu compounds have recently shown promise for building dense, optically addressable quantum memory as the cations' long nuclear spin coherence times and shielded 4f electron optical transitions provide reliable memory platforms. Implementing such a system, though, requires ultranarrow, inhomogeneous linewidth compounds. Finding this rare linewidth behavior within a wide range of potential chemical spaces remains difficult, and while exploratory synthesis is often guided by density functional theory (DFT) calculations, lanthanides' 4f electrons pose unique challenges for stability predictions.

Exfoliable Transition Metal Chalcogenide Semiconductor NbSeI.

As the field of exfoliated van der Waals electronics grows to include complex heterostructures, the variety of available in-plane symmetries and geometries becomes increasingly valuable. In this work, we present an efficient chemical vapor transport synthesis of NbSeI with the triclinic space group 1̅. This material contains Nb-Nb dimers and an in-plane crystallographic angle γ = 61.

Ultrafast X-Ray Scattering Reveals Composite Amplitude Collective Mode in the Weyl Charge Density Wave Material (TaSe_{4})_{2}I.

We report ultrafast x-ray scattering experiments of the quasi-1D charge density wave (CDW) material (TaSe_{4})_{2}I following ultrafast infrared photoexcitation. From the time-dependent diffraction signal at the CDW sidebands we identify a 0.11 THz amplitude mode derived primarily from a transverse acoustic mode of the high-symmetry structure.

Observation of a massive phason in a charge-density-wave insulator.

The lowest-lying fundamental excitation of an incommensurate charge-density-wave material is believed to be a massless phason-a collective modulation of the phase of the charge-density-wave order parameter. However, long-range Coulomb interactions should push the phason energy up to the plasma energy of the charge-density-wave condensate, resulting in a massive phason and fully gapped spectrum. Using time-domain terahertz emission spectroscopy, we investigate this issue in (TaSe)I, a quasi-one-dimensional charge-density-wave insulator.

Angstrom-scale imaging of magnetization in antiferromagnetic FeAs via 4D-STEM.

We demonstrate a combination of computational tools and experimental 4D-STEM methods to image the local magnetic moment in antiferromagnetic FeAs with 6 angstrom spatial resolution. Our techniques utilize magnetic diffraction peaks, common in antiferromagnetic materials, to create imaging modes that directly visualize the magnetic lattice. Using this approach, we show that center-of-mass analysis can determine the local magnetization component in the plane perpendicular to the path of the electron beam.

Quasi-One-Dimensional Transition-Metal Chalcogenide Semiconductor (NbSeI)I.

The discovery of new low-dimensional transition-metal chalcogenides is contributing to the already prosperous family of these materials. In this study, needle-shaped single crystals of a quasi-one-dimensional (1D) material, (NbSeI)I, were grown by chemical vapor transport, and the structure was solved by single-crystal X-ray diffraction (XRD). The structure has 1D (NbSeI) chains along the [101] direction, with two I ions per formula unit directly bonded to Nb.

Ultra-Wide Band Gap GaO-on-SiC MOSFETs.

Ultra-wide band gap semiconductor devices based on β-phase gallium oxide (GaO) offer the potential to achieve higher switching performance and efficiency and lower manufacturing cost than that of today's wide band gap power electronics. However, the most critical challenge to the commercialization of GaO electronics is overheating, which impacts the device performance and reliability. We fabricated a GaO/4H-SiC composite wafer using a fusion-bonding method.

Formation and impact of nanoscopic oriented phase domains in electrochemical crystalline electrodes.

Electrochemical phase transformation in ion-insertion crystalline electrodes is accompanied by compositional and structural changes, including the microstructural development of oriented phase domains. Previous studies have identified prevailingly transformation heterogeneities associated with diffusion- or reaction-limited mechanisms. In comparison, transformation-induced domains and their microstructure resulting from the loss of symmetry elements remain unexplored, despite their general importance in alloys and ceramics.

Pharmacologically Enhanced Regulatory Hematopoietic Stem Cells Revert Experimental Autoimmune Diabetes and Mitigate Other Autoimmune Disorders.

Type 1 diabetes (T1D) is characterized by the loss of immune self-tolerance, resulting in an aberrant immune responses against self-tissue. A few therapeutics have been partially successful in reverting or slowing down T1D progression in patients, and the infusion of autologous hematopoietic stem cells (HSCs) is emerging as an option to be explored. In this study, we proposed to pharmacologically enhance by ex vivo modulation with small molecules the immunoregulatory and trafficking properties of HSCs to provide a safer and more efficacious treatment option for patients with T1D and other autoimmune disorders.

GaO-on-SiC Composite Wafer for Thermal Management of Ultrawide Bandgap Electronics.

β-phase gallium oxide (GaO) is an emerging ultrawide bandgap (UWBG) semiconductor ( ∼ 4.8 eV), which promises generational improvements in the performance and manufacturing cost over today's commercial wide bandgap power electronics based on GaN and SiC. However, overheating has been identified as a major bottleneck to the performance and commercialization of GaO device technologies.

Electrodeposition of atmosphere-sensitive ternary sodium transition metal oxide films for sodium-based electrochemical energy storage.

We introduce an intermediate-temperature (350 °C) dry molten sodium hydroxide-mediated binder-free electrodeposition process to grow the previously electrochemically inaccessible air- and moisture-sensitive layered sodium transition metal oxides, NaMO (M = Co, Mn, Ni, Fe), in both thin and thick film form, compounds which are conventionally synthesized in powder form by solid-state reactions at temperatures ≥700 °C. As a key motivation for this work, several of these oxides are of interest as cathode materials for emerging sodium-ion-based electrochemical energy storage systems. Despite the low synthesis temperature and short reaction times, our electrodeposited oxides retain the key structural and electrochemical performance observed in high-temperature bulk synthesized materials.

Inflexible stoichiometry in bulk pyrite FeS as viewed by in situ and high-resolution X-ray diffraction.

Non-stoichiometry is considered to be one of the main problems limiting iron pyrite, FeS, as a photovoltaic absorber material. Although some historical diffraction experiments have implied a large solubility range of FeS with δ up to 0.25, the current consensus based on calculated formation energies of intrinsic defects has lent support to line-compound behavior.

Oxygen-Induced Ordering in Bulk Polycrystalline CuZnSnS by Sn Removal.

Solid-state nuclear magnetic resonance spectroscopy, X-ray diffraction, and Raman spectroscopy were used to show that CuZnSnS (CZTS) bulk solids grown in the presence of oxygen had improved cation ordering compared to bulk solids grown without oxygen. Oxygen was shown to have negligible solubility in the CZTS phase. The addition of oxygen resulted in the formation of SnO, leading to Sn-deficient CZTS.

GSK3 Inhibition Drives Maturation of NK Cells and Enhances Their Antitumor Activity.

Maturation of human natural killer (NK) cells as defined by accumulation of cell-surface expression of CD57 is associated with increased cytotoxic character and TNF and IFNγ production upon target-cell recognition. Notably, multiple studies point to a unique role for CD57 NK cells in cancer immunosurveillance, yet there is scant information about how they mature. In this study, we show that pharmacologic inhibition of GSK3 kinase in peripheral blood NK cells expanded with IL15 greatly enhances CD57 upregulation and late-stage maturation.

Structural, Electronic, and Optical Properties of KSnO with an Offset Hollandite Structure.

We present the compound KSnO, a Sn-containing oxide with a unique structure type among oxides. The compound is orthorhombic and reminiscent of an offset hollandite, where open channels hold a row of four K per channel per cell. UV-visible spectroscopy indicates a wide band gap semiconductor, which is confirmed by first-principles electronic-structure calculations of band structures, densities of states, and optical properties.

Crystal growth and characterization of the narrow-band-gap semiconductors OsPn₂ (Pn = P, As, Sb).

Using metal fluxes, crystals of the binary osmium dipnictides OsPn2 (Pn = P, As, Sb) have been grown for the first time. Single-crystal X-ray diffraction confirms that these compounds crystallize in the marcasite structure type with orthorhombic space group Pnnm. The structure is a three-dimensional framework of corner- and edge-sharing OsPn6 octahedra, as well as [Pn2(4-)] anions.

Prostaglandin-modulated umbilical cord blood hematopoietic stem cell transplantation.

Umbilical cord blood (UCB) is a valuable source of hematopoietic stem cells (HSCs) for use in allogeneic transplantation. Key advantages of UCB are rapid availability and less stringent requirements for HLA matching. However, UCB contains an inherently limited HSC count, which is associated with delayed time to engraftment, high graft failure rates, and early mortality.

NaBa2Cu3S5: a doped p-type degenerate semiconductor.

Mixed S(2-/)S(1-) oxidation states have been discovered in the new quaternary compound NaBa2Cu3S5. Synthesized from the reaction of Cu in a molten alkali metal/polysulfide flux, the compound crystallizes in monoclinic space group C2/m with a = 16.5363(7) Å, b = 5.

Understanding fluxes as media for directed synthesis: in situ local structure of molten potassium polysulfides.

Rational exploratory synthesis of new materials requires routes to discover novel phases and systematic methods to tailor their structures and properties. Synthetic reactions in molten fluxes have proven to be an excellent route to new inorganic materials because they promote diffusion and can serve as an additional reactant, but little is known about the mechanisms of compound formation, crystal precipitation, or behavior of fluxes themselves at conditions relevant to synthesis. In this study we examine the properties of a salt flux system that has proven extremely fertile for growth of new materials: the potassium polysulfides spanning K(2)S(3) and K(2)S(5), which melt between 302 and 206 °C.

A novel platform to enable the high-throughput derivation and characterization of feeder-free human iPSCs.

Human induced pluripotent stem cells (hiPSCs) hold enormous potential, however several obstacles impede their translation to industrial and clinical applications. Here we describe a platform to efficiently generate, characterize and maintain single cell and feeder-free (FF) cultured hiPSCs by means of a small molecule cocktail media additive. Using this strategy we have developed an effective multiplex sorting and high-throughput selection platform where individual clonal hiPSC lines are readily obtained from a pool of candidate clones, expanded and thoroughly characterized.