Effect of strain on charge density wave order in \alpha-U

The effect of strain on charge density wave (CDW) order in $\alpha$-U is investigated within the framework of relativistic density-functional theory. The energetical stability of $\alpha$-U with CDW distortion is enhanced by the tensile strain along $a$ and $b$ directions, which is similar to the case of negative pressure and normal. However, the tensile strain along $c$ direction suppresses the energetical stability of CDW phase. This abnormal effect could be understood from the emergence of a new one-dimensional atomic chain along $c$ direction in $\alpha$-U. Furthermore, this effect is supported by the calculations of Fermi surface and phonon mode, in which the topological objects and the dynamical instability show opposite behavior between strain along $a$/$b$ and $c$ directions

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly

Passivating Surface States on Water Splitting Cuprous Oxide Photocatalyst with Bismuth Decoration

To enhance the visible light photocatalystic activity of Cu 2 O(100) surface, we performed first-principles calculations on the structural, electronic and optical properties of a bismuth (Bi)-decorated Cu 2 O(100) surface (Bi@Cu 2 O(100)). It is shown that the Bi prefer to be loaded to the hollow sites among four surface oxygen atoms and tend to individual dispersion instead of aggregating on the surface due to the lowest formation energy and larger distance between two Bi atoms at the surface than the Bi clusters; the coverage of around 0.25 monolayer Bi atoms can effectively eliminate the surface states and modify the band edges to satisfy the angular momentum selection rules for light excited transition of electrons, and the loaded Bi atoms contribute to the separation of photogenerated electron-holes. The relative positions between the band edges and the redox potentials are suitable for photocatalytic hydrogen production from the redox water, and moreover, the optical absorption spectrum indicates a positive response of the Bi 0 . 25 @Cu 2 O(100) to visible light, implying that the Bi 0 . 25 @Cu 2 O(100) is a promising visible light photocatalyst

Thermoelectric performance of MoSi

Thermoelectric performance of MoSi2As4 monolayer is investigated using density functional theory combined with Boltzmann transport theory. The maximal power factors of n- and p-type by the PBE (HSE06) functional are 7.73 (48.31) and 32.84 $(30.50)\ \text{mW m}^{-1}\text{ K}^{-2}$ at the temperature of 1200 K, respectively. The lattice thermal conductivity is less than $30\ \text{W m}^{-1}\text{ K}^{-1}$ above 800 K. The thermoelectric figure of merit can reach 0.33 (0.58) and 0.90 (0.81) using the PBE (HSE06) functional for n- and p-type under appropriate carrier concentration at 1200 K, respectively. Thus, the p-type MoSi2As4 monolayer is predicted to be a potential candidate for high-temperature thermoelectric applications

L21 and XA ordering competition in titanium-based full-Heusler alloys

The site preference rule, i.e., that the atomic sites of transition-metal-elements X and Y are determined by the number of their valence electrons, has been widely used in the design of full-Heusler alloys X 2 YZ and also used to explain their properties. In this work, the most popular Ti 2 -based Heusler alloys are selected as targets to study the site preferences of their atoms by theoretical calculations. It is observed that most of them are likely to form the L2 1 -type structure instead of the XA one. The reason for the site preference is explained on the basis of the calculated charge density differences. We further prove that each alloy shows abruptly different spintronic properties, depending on its L2 1 -type or XA-type structures. This research can be regarded as a counterexample to the site preference rule and is instructive for the future design of full-Heusler alloy materials

Predicted hexagonal titanium nitride monolayer as an intrinsic ferromagnetic semiconductor

Two-dimensional (2D) magnetic semiconductors have great promising for energy-efficient ultracompact spintronics due to the low-dimensional ferromagnetic and semiconducting behavior. Here, we predict hexagonal titanium nitride monolayer (h-TiN) to be a ferromagnetic semiconductor by investigating stability, magnetism, and carrier transport of h-TiN using the first-principles calculations. The thermodynamical stability of h-TiN is revealed by phonon dispersion, molecular dynamics simulation and formation energy. The energy band structure shows that h-TiN is a ferromagnetic semiconductor with medium magnetic anisotropy, the magnetic moment of 1μB and the band gaps of 1.33 and 4.42 eV for spin-up and -down channels, respectively. The Curie temperature of h-TiN is estimated to be about 205 K by mean-field theory and not enhanced by the compressive and tensile strains. Higher carrier mobility, in-plane stiffness and conductivity indicate that h-TiN has favorable transport performance. The ferromagnetic semiconducting behavior is robust against the external strains, indicating that h-TiN could be a rare candidate for nanoscale spintronic devices

Magnetic Weyl and quadratic nodal lines in inverse-Heusler-based fully compensated ferrimagnetic half-metals

Heusler alloys, a class of easily prepared, highly ordered intermetallic compounds, were first reported in 1903. Since then, Heusler alloys have presented various physical phenomena in modern condensed-matter physics. Among Heusler alloys, Heusler-based fully compensated ferrimagnetic half-metals (FCF-HMs) are, particularly, relevant because they host fully spin polarization and have no net magnetic moment, making them have no stray field and less affected by external magnetic fields. Based on first-principles calculations and a tight-binding Hamiltonian model, we provide new insight into inverse-Heusler-based (IHB) FCF-HMs and reveal that they exhibit spin-polarized Weyl and quadratic nodal lines as well as spin-polarized drumheadlike surface states. This paper presents the electron-filling-based design rule and material candidates for IHB FCF-HMs and suggests that IHB FCF-HMs are promising candidates for follow-up investigations in the field of topological spintronics. Subsequent experimental confirmation of the topological states in IHB FCF-HMs is imminent

Degenerate line modes in the surface and bulk phonon spectra of orthorhombic NaMgF3perovskite

Degenerate bulk-line phonon modes have been widely reported in various crystal system types; however, degenerate surface-line phonon modes have only been reported in monoclinic crystal systems, such as SnIP with space group P 2 / c (No. 13). Herein, we propose that degenerate surface-line phonon modes can also emerge in solids with orthorhombic structures. Based on first-principle calculations and symmetry analysis, we propose that orthorhombic NaMgF3 fluoroperovskite with space group Pnma (No. 62) is a material candidate with degenerate line states in both the bulk phonon mode and the (010) surface phonon mode. We discovered four closed nodal loops (two type-I and two hybrid-type) on the ky = 0 plane in the bulk phonon mode, all of which coexisted with Dirac points on the Z-U and X-U paths. Moreover, we discovered symmetry-projected doubly degenerate nodal lines along the X ¯ - U ¯ surface path in the (010) surface phonon mode. The proposed degenerate surface-line phonons in NaMgF3 is quite clean and protected by symmetries, which will aid future experimental detection

Thermoelectric Properties of NiCl3 Monolayer: A First-Principles-Based Transport Study

By employing the first-principles-based transport theory, we investigate the thermoelectric performance based on the structural and electronic properties of NiCl 3 monolayer. The NiCl 3 monolayer is confirmed to be a stable Dirac spin gapless semiconductor with the linear energy dispersion having almost massless carrier, high carrier mobility and fully spin-polarization. Further, NiCl 3 monolayer processes the optimum power factor of 4.97 mWm − 1 K − 2 , the lattice thermal conductivity of 1.89 Wm − 1 K − 1 , and the dimensionless figure of merit of 0.44 at room temperature under reasonable carrier concentration, indicating that NiCl 3 monolayer may be a potential matrix for promising thermoelectrics