Bingwen Zhang

Spintronics is rooted in diverse spin textures by locking spin and momentum to realize higher conversion rate between spin and charge in order to be applied in real devices. Janus two‐dimensional materials naturally break space inversion symmetry, benefiting spintronic devices. Here, we perform first‐principles density functional theory calculations on structural, electronic, and spin properties of Janus monolayer mixed halide lead material. Inversion symmetry breaking with strong spin–orbital coupling (SOC) of Pb‐p and halide‐p orbitals induces giant Rashba‐like splitting for both valence bands and conduction bands, which extends diverse spin texture patterns. The maximum splitting energy of conduction bands is up to a factor of four larger than that of valence bands due to strong SOC of Pb and its geometry location. The spin‐projected band structure of PbBrI suggests that there exist out‐of‐plane S _z components, which is different from conventional two‐dimensional Janus materials. Based on symmetry analysis and k ⋅ p model, irreducible representations of conduction bands support the conventional Rashba spin splitting. Our simulated results are useful to pave the way for integrating Janus lead halide monolayer materials into potential spin‐ and orbital‐based devices.

Topological semimetals, especially topological semimetallic carbon-based materials, exhibit high electrical conductivity that is resistant to disruptions from defects or impurities, making them ideal alternatives as anode materials for sodium-ion batteries (SIBs). Recently, a novel two-dimensional carbon allotrope known as graphene+ was theoretically proposed [Yu et al., Cell Rep. Phys Sci., 3, 100790 (2022)], and because of its fascinating features, it shows potential for a variety of applications. In this study, we proposed two new two-dimensional carbon-based materials named M₂C₇ (M = B and Si) monolayers, which can be obtained by doping boron and silicon atoms into graphene+ at sp²-site, and thoroughly investigated their suitability for use as SIB anode materials. We found they exhibit distinctive mechanical and electronic properties, including negative Poisson's ratios and topological Dirac nodal-line semimetal features, along with excellent dynamic, mechanical, and thermal stability. Particularly noteworthy is that M₂C₇ (M = B and Si) monolayers show high energy densities for Na adsorption attributed to their elevated storage capacity (2028.65 and 1528.76 mA h g^-1), lower barrier energy (0.29 and 0.14 eV), and minimal volumetric variation (1.0% and 0.27%) compared to pristine graphene+ (with values of 1487.70 mA h g^-1, 0.16 eV, and 0.30%, respectively). These findings demonstrate the potential of M₂C₇ monolayers as high-performance SIB anode materials.

A stable 2D CrSc₂Te₄ ferromagnetic (FM) half-metal monolayer with a wide bandgap of 1.02 eV and high Curie temperature (T_c) of 326 K is proposed. It showcases exceptional properties for spintronics applications (TMR: 6087.07%).

Two-dimensional photocatalytic materials have emerged as prominent materials within ecological and energy catalysis in recent years. Among these materials, two-dimensional Janus structures, including PdXY (X = S, Se; Y = Se, Te), MXY (M = Mo, W; X, Y = S, Se, Te), and MSiGeN₄ (M = Mo, W), have been highlighted as prospective candidates for water-splitting photocatalysts. In this paper, we have explored BiSY (Y = I, Br, Cl) as a promising material for overall water-splitting, utilizing first-principles calculations to investigate the geometric structure, stability, electronic structure, and optical properties. By analyzing the results of phonon band structures, molecular dynamics simulations, and the elasticity coefficient, we can establish the system stability of BiSY (Y = I, Br, Cl). And HSE06 energy band calculations and band edge position calculations demonstrated that BiSY (Y = I, Br, Cl) possesses an appropriate band gap. Moreover, the absorption spectra and step reaction diagrams validated the feasibility of photocatalytic water-splitting of BiSY (Y = I, Br, Cl). Additionally, we confirmed that biaxial strain can change the band edge position of BiSY (Y = I, Br, Cl). Our comprehensive analysis shows that BiSY (Y = I, Br, Cl) is a potential candidate for efficient water-splitting photocatalysts. This study contributes to the growing collection of two-dimensional Janus photocatalysts.

The quantum anomalous Hall (QAH) effect has recently drawn great attention in spintronics with extraordinary property of chiral edge states without dissipation in absence of magnetic field. In M₂X₃ honeycomb Kagome lattice, numerous two-dimensional materials are predicted to be QAH insulators including metal oxides/sulfides and metal organic lattice. In this work, we proposed a general model to explain the mechanism of Dirac half metal with absence of spin orbital coupling and the nontrivial topological property with spin orbital coupling, which could be induced by combination of electron counting rule, crystal field effect and d x z , d y z orbitals hybridization. Based on the mechanism, we further predict that triphenyl-metal lattice M₂(C₆H₄)₃ (M = V, Nb, Ta) are all QAH insulators with high Curie temperature and large nontrivial band gap for triphenyl-Nb and triphenyl-Ta lattice.