The newly synthesized two-dimensional polyaniline (C3N) is structurally similar to graphene, and has interesting electronic, magnetic, optical, and thermal properties. Motivated by the fact that point defects in graphene give rise to interesting features, like magnetization in an all carbon material, we perform density functional theory calculations to investigate vacancy and Stone-Wales type point defects in monolayer C3N. We compare and contrast the structural, electronic and magnetic properties of these defects with those in graphene. While monovacancies and Stone-Wales defects of C3N result in reconstructions similar to those in graphene, divacancies display dissimilar geometrical features. Different from graphene, all vacancies in C3N have metallic character because of altered stoichiometry, those which have low-coordinated atoms have finite magnetic moments. We further investigate the robustness of the reconstructed structures and the changes in the magnetic moments by applying tensile and compressive biaxial strain. We find that, with the advantage of finite band gap, point defects in C3N are qualified as good candidates for future spintronics applications.
The defect-free transfer of chemical vapour deposition (CVD) grown monolayer MoS2 is important for both fabrication of 2D devices and fundamental point of view for various studies where substrate effects need to be minimized. Among many transfer techniques, two well-known techniques that use the polymer as carriers are wet-transfer technique and the surface-energy-assisted transfer technique. In this work, we transferred a single CVD grown monolayer MoS2 by these two transfer methods on a similar substrate, and the intervention of strain and defects in the transfer process is probed by Raman a…
The electronic and the optical properties of metallic nitride (MN) monolayers are studied using a DFT formalism. In most of these monolayers, the electron density of the metallic atoms is much higher than that of the nitride atoms, and ionic, covalent, and metallic bonds are found in M-N bonds, resulting in fascinating electronic and optical properties. The optical band gap is varied from almost $0.0$ to $3.0$~eV for the MN monolayers depending on the bond type between the metallic and the nitride atoms, as well as the contribution of the type of orbitals around the Fermi energy. The optical p…
The electronic structure and elastic property of monolayer and bilayer transition metal dichalcogenides MX$_2$ (M=Mo,W;X=O,S,Se,Te): A comparative first-principles study
Germanium selenide (GeSe) is a unique two-dimensional (2D) material showing various polymorphs stable at ambient condition. Recently, a new phase with a layered hexagonal lattice (γ-GeSe) was synthesized with ambient stability and extraordinary electronic conductivity even higher than graphite while its monolayer is semiconducting. In this work, via using first-principles derived force constants and Boltzmann transport theory we explore the lattice thermal conductivity (κ_l) of the monolayer γ-GeSe, together with a comparison with monolayer α-GeSe and β-GeSe. The κ_l of γ-phase is relatively l…
With the successful synthesis of the two-dimensional (2D) gallium nitride (GaN) in a planar honeycomb structure, the phonon transport properties of 2D GaN have been reported. However, it remains unclear for the thermal transport in Ga-based materials by substituting N to other elements in the same main group, which is of more broad applications. In this paper, based on first-principles calculations, we performed a comprehensive study on the phonon transport properties of 2D GaX (X = N, P, and As) with planar or buckled honeycomb structures. The thermal conductivity of GaP (1.52 Wm-1K-1) is fou…
Recently a novel two-dimensional (2D) C$_{60}$ based crystal called quasi-hexagonal-phase fullerene (QHPF) has been fabricated and demonstrated to be a promising candidate for 2D electronic devices [Hou et al. Nature 606, 507-510 (2022)]. We construct an accurate and transferable machine-learned potential to study heat transport and related properties of this material, with a comparison to the face-centered-cubic bulk-phase fullerene (BPF). Using the homogeneous nonequilibrium molecular dynamics and the related spectral decomposition methods, we show that the thermal conductivity in QHPF is an…
Transition metal dichalcogenide (TMD) monolayers attract great attention due to their specific structural, electronic and mechanical properties. The formation of their lateral heterostructures allows a new degree of flexibility in engineering electronic and optoelectronic devices. However, the mechanical properties of the lateral heterostructures are rarely investigated. In this study, a comparative investigation on the mechanical characteristics of 1H, 1T' and 1H/1T' heterostructure phases of different TMD monolayers including molybdenum disulfide (MoS2) molybdenum diselenide (MoSe2), Tungste…
We investigate the impact of mechanical strain, stacking order, and external electric fields on the magnetic interactions of a two-dimensional (2D) van der Waals (vdW) heterostructure in which a 2D ferromagnetic metallic Fe$_3$GeTe$_2$ monolayer is deposited on germanene. Three distinct computational approaches based on \textit{ab initio} methods are used, and a careful comparison is given: (i) The Green's function method, (ii) the generalized Bloch theorem, and (iii) the supercell approach. First, the shell-resolved exchange constants are calculated for the three Fe atoms within the unit cell…
In this letter, we highlight the enhanced functionalization of the electronic and optical properties in the hybrid heterojunction of 1D Tellurene with 2D monolayer of Graphene and MoS2 in both lateral and vertical geometries, having potential applications in the field of photonics and energy harvesting. The structural geometries of the lateral and vertical assemblies are optimized with a comparative and systematic analysis of the energetics of the different positional placement of the 1D system with respect to the hexagonal 2D layer. The 1D/2D coupling of the electronic structure in this uniqu…
The recent experimental synthesis of 2D graphitic C3N5 has attracted lot of interests in its electronic and optical properties and its comparison with other graphitic C3N4 and C3N3. To this end, we performed DFT calculations using more accurate HSE06 functional and estimated the corresponding electronic properties. From a comparative study of the band structures of C3N3, C3N4, and C3N5, we found that, the electronic band-gap decreases as 3.24 eV (C3N3) > 2.81 eV (C3N4) > 2.19 eV (C3N5) with increase in the number of nitrogen atoms in the unit cell of these graphitic carbon nitrides. Further, t…
Magnetoelastic honeycomb fragmentation in VI$_{3}$
University of Edinburgh（爱丁堡大学）；NIST Center for Neutron Research（美国国家标准与技术研究院中子研究中心）；University of Maryland, College Park（马里兰大学帕克分校）；ISIS Facility, Rutherford Appleton Laboratory（卢瑟福·阿普尔顿实验室 ISIS 设施）；European Synchrotron Radiation Facility（欧洲同步辐射装置）
