Twist-Angle Tuning of Electronic Structure in Two-Dimensional Dirac Nodal Line Semimetal AuGe on Au(111).

Topological semimetals have emerged as quantum materials including Dirac, Weyl, and nodal line semimetals, and so on. Dirac nodal line (DNL) semimetals possess topologically nontrivial bands crossing along a line or a loop and are considered precursor states for other types of semimetals. Here, we combine scanning tunneling microscopy/spectroscopy (STM/S) measurements and density functional theory (DFT) calculations to investigate a twist angle tuning of electronic structure in two-dimensional DNL semimetal AuGe.

Two-Dimensional Artificial Ge Superlattice Confining in Electronic Kagome Lattice Potential Valleys.

Constructing two-dimensional (2D) artificial superlattices based on single-atom and few-atom nanoclusters is of great interest for exploring exotic physics. Here we report the realization of two types of artificial germanium (Ge) superlattice self-confined by a R25.3° superstructure of bismuth (Bi) induced electronic kagome lattice potential valleys.

Realization of black phosphorus-like PbSe monolayer on Au(111) via epitaxial growth.

Lead selenide (PbSe) has been attracted a lot attention in fundamental research and industrial applications due to its excellent infrared optical and thermoelectric properties, toward reaching the two-dimensional limit. Herein, we realize the black phosphorus-like PbSe (-phase PbSe) monolayer on Au(111) via epitaxial growth, where a characteristic rectangular superlattice of 5 Å × 9 Å corresponding to 1 × 2 reconstruction with respect to the pristine of-phase PbSe is observed by scanning tunneling microscopy. Corresponding density functional theory calculation confirmed the reconstruction and revealed the driven mechanism, the coupling between monolayer PbSe and Au(111) substrate.

First-principles study on the electronic and optical properties of AlSb monolayer.

Using density functional theory and many-body perturbation theory, we systematically investigate the optoelectronic properties of AlSb monolayer, which has been recently synthesized by molecular beam epitaxy [ACS Nano 2021, 15, 5, 8184-8191]. After confirming the dynamical stability of the monolayer, we analyze its electronic properties at different levels of theory without (PBE, HSE03, HSE06) and with (G[Formula: see text]W[Formula: see text], GW[Formula: see text], and GW) electron-electron interaction. The results show that AlSb monolayer is a semiconductor with a direct quasiparticle band gap of 1.

The effects of substrate and stacking in bilayer borophene.

Bilayer borophene has recently attracted much interest due to its outstanding mechanical and electronic properties. The interlayer interactions of these bilayers are reported differently in theoretical and experimental studies. Herein, we design and investigate bilayer [Formula: see text] borophene, by first-principles calculations.

Electronic Tuning in WSe/Au via van der Waals Interface Twisting and Intercalation.

The transition metal dichalcogenide (TMD)-metal interfaces constitute an active part of TMD-based electronic devices with optimized performances. Despite their decisive role, current strategies for nanoscale electronic tuning remain limited. Here, we demonstrate electronic tuning in the WSe/Au interface by twist engineering, capable of modulating the WSe carrier doping from an intrinsic p-type to n-type.

Thermoelectric characteristics of X[Formula: see text]YH[Formula: see text] monolayers (X=Si, Ge; Y=P, As, Sb, Bi): a first-principles study.

Ever since global warming emerged as a serious issue, the development of promising thermoelectric materials has been one of the main hot topics of material science. In this work, we provide an in-depth understanding of the thermoelectric properties of X[Formula: see text]YH[Formula: see text] monolayers (X=Si, Ge; Y=P, As, Sb, Bi) using the density functional theory combined with the Boltzmann transport equation. The results indicate that the monolayers have very low lattice thermal conductivities in the range of 0.

Mechanical strength and flexibility in [Formula: see text]-4H borophene.

Very recently, a novel phase of hydrogenated borophene, namely [Formula: see text]-4H, has been synthesized in a free-standing form. Unlike pure borophenes, this phase shows very good stability in the air environment and possesses semiconducting characteristics. Because of the interesting stiffness and flexibility of borophenes, herein, we systematically studied the mechanical properties of this novel hydrogenated phase.

Thermoelectric properties of hydrogenated SnBi monolayer under mechanical strain: a DFT approach.

Bismuth based structures are among the most promising candidates for thermoelectric applications. Recently, a semiconducting binary compound with stoichiometry of Sn2Bi has been synthesized, showing a strong spin-orbit coupling effect and high electron-hole asymmetry. Motivated by the experiment, we performed a density functional theory calculation combined with the semiclassical Boltzmann transport equation to investigate the thermoelectric properties of the stabilized Sn2Bi monolayer.

Prediction of hydrogenated group IV-V hexagonal binary monolayers.

Group IV and V monolayers are very crucial 2D materials for their high carrier mobilities, tunable band gaps, and optical linear dichroism. Very recently, a novel group IV-V binary compound, [Formula: see text], has been synthesized on silicon substrate, and has shown very interesting electronic properties. Further investigations have revealed that the monolayer would be stable in freestanding form by hydrogenation.

Edge-Dependent Electronic and Magnetic Characteristics of Freestanding -Borophene Nanoribbons.

This work presents an investigation of nanoribbons cut from -borophene sheets by applying the density functional theory. In particular, the electronic and magnetic properties of borophene nanoribbons (BNR) are studied. It is found that all the ribbons considered in this work behave as metals, which is in good agreement with the recent experimental results.

Freestanding χ-borophene nanoribbons: a density functional theory investigation.

Experimental observation of borophene nanoribbons (BNRs) motivated us to carry out a comprehensive investigation on BNRs, decomposed from a χ3 sheet, using density functional theory. Our results show that the stability and also the electrical and magnetic properties of the ribbons are strongly dependent on the edge configurations. We have studied two categories of ribbon: XBNRs and YBNRs.

Current-voltage characteristics of borophene and borophane sheets.

Motivated by recent experimental and theoretical research on a monolayer of boron atoms, borophene, the current-voltage characteristics of three different borophene sheets, 2Pmmn, 8Pmmn, and 8Pmmm, are calculated using density functional theory combined with the nonequilibrium Green's function formalism. Borophene sheets with two and eight atoms in a unit cell are considered. Their band structure, electron density, and structural anisotropy are analyzed in detail.

Improvement of thermoelectric efficiency of the polyaniline molecular junction by the doping process.

Thermoelectric properties of a polyaniline molecular junction with face centered cubic electrodes are investigated using the Green function formalism in a linear response regime in the presence of the doping process. Doping causes the increase of thermopower and the figure of merit (ZT) and the decrease of electrical conductance as found experimentally in the work of Li et al., (Synthetic.