scholarly journals Intercalated architecture of MA2Z4 family layered van der Waals materials with emerging topological, magnetic and superconducting properties

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lei Wang ◽  
Yongpeng Shi ◽  
Mingfeng Liu ◽  
Ao Zhang ◽  
Yi-Lun Hong ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Layer Structure ◽  
Atomic Layer ◽  
Type I ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Valence Electrons ◽  
Nonmagnetic Metals ◽  
Standard Density

AbstractThe search for new two-dimensional monolayers with diverse electronic properties has attracted growing interest in recent years. Here, we present an approach to construct MA2Z4 monolayers with a septuple-atomic-layer structure, that is, intercalating a MoS2-type monolayer MZ2 into an InSe-type monolayer A2Z2. We illustrate this unique strategy by means of first-principles calculations, which not only reproduce the structures of MoSi2N4 and MnBi2Te4 that were already experimentally synthesized, but also predict 72 compounds that are thermodynamically and dynamically stable. Such an intercalated architecture significantly reconstructs the band structures of the constituents MZ2 and A2Z2, leading to diverse electronic properties for MA2Z4, which can be classified according to the total number of valence electrons. The systems with 32 and 34 valence electrons are mostly semiconductors. Whereas, those with 33 valence electrons can be nonmagnetic metals or ferromagnetic semiconductors. In particular, we find that, among the predicted compounds, (Ca,Sr)Ga2Te4 are topologically nontrivial by both the standard density functional theory and hybrid functional calculations. While VSi2P4 is a ferromagnetic semiconductor and TaSi2N4 is a type-I Ising superconductor. Moreover, WSi2P4 is a direct gap semiconductor with peculiar spin-valley properties, which are robust against interlayer interactions. Our study thus provides an effective way of designing septuple-atomic-layer MA2Z4 with unusual electronic properties to draw immediate experimental interest.

Properties of single-layer graphene with supercell doped by one defect only

2017 ◽  
Vol 31 (27) ◽  
pp. 1750196
Author(s):  
Zongguo Wang ◽  
Shaojing Qin ◽  
Chuilin Wang
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Magnetic State ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Monolayer Graphene ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Spin Polarized ◽  
Different Types

Graphene has vast promising applications in nanoelectronics and spintronics because of its unique magnetic and electronic properties. Making use of an ab initio spin-polarized density functional theory, implemented by the method of the Heyd–Scuseria–Ernzerhof 06 (HSE06) hybrid functional, the properties of various defect dopants in a supercell of a semi-metal monolayer graphene were investigated. We found from our calculation that introducing one defect dopant in a supercell would break the spin sublattice symmetry, and will induce a magnetic state at some appropriate doping concentrations. This paper systematically analyzes the magnetic effects of three types of defects on graphene, that is, vacancy, substitutional dopant and adatoms. Different types of defects will induce various new properties in graphene. The energies and electronic properties of these three types of defects were also calculated.

Silicon Carbide: A Playground for 1D-Modulation Electronics

2006 ◽  
Vol 527-529 ◽  
pp. 355-358 ◽  
Author(s):  
Peter Deák ◽  
Adam Buruzs ◽  
Adam Gali ◽  
Thomas Frauenheim ◽  
Wolfgang J. Choyke
Keyword(s):  
Density Functional ◽  
Spatial Separation ◽  
Atomic Layer ◽  
Periodic Variation ◽  
Optical Nonlinearity ◽  
Double Layers ◽  
Hybrid Functional ◽  
Free Electrons ◽  
Functional Theory ◽  
Molecular Source

Optoelectronic devices with 1D modulation of the potential through hetero-structure or doping superlattices have so far been the privilege of III-V semiconductors. Based on the fact that SiC can be grown monolayer by monolayer, and that Si–Si and C–C double layers have been observed in it, we suggest the possibility of a stress-free polarization superlattice, consisting of the periodic variation of Si-face and C-face domains along the hexagonal axis of 4H-SiC. Such a structure could, in principle, be grown by molecular source atomic layer epitaxy. Investigating such superlattices by density functional theory, using a hybrid functional, we show that Si–Si and C–C double layers at the antiphase boundaries confine electrons within ~0.5 nm, and the periodic polarization field causes zig-zag shaped band edges which gives rise to tunable absorption, to spatial separation of free electrons and holes, as well as to optical nonlinearity. These properties could allow the application of SiC also in optoelectronics and photonics.

scholarly journals Electronic properties of several two dimensional halides from ab initio calculations

2019 ◽  
Vol 10 ◽  
pp. 823-832 ◽  
Author(s):  
Mohamed Barhoumi ◽  
Ali Abboud ◽  
Lamjed Debbichi ◽  
Moncef Said ◽  
Torbjörn Björkman ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electric Field ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electronic Properties ◽  
Density Functional ◽  
Two Dimensional ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Phonon Spectra

Using density functional theory, we study the electronic properties of several halide monolayers. We show that their electronic bandgaps, as obtained with the HSE hybrid functional, range between 3.0 and 7.5 eV and that their phonon spectra are dynamically stable. Additionally, we show that under an external electric field some of these systems exhibit a semiconductor-to-metal transition.

scholarly journals Bayesian Optimization of Hubbard U’s for Investigating InGaN Superlattices

2021 ◽  
Vol 2 (3) ◽  
pp. 370-381
Author(s):  
Maxim N. Popov ◽  
Jürgen Spitaler ◽  
Lorenz Romaner ◽  
Natalia Bedoya-Martínez ◽  
René Hammer
Keyword(s):  
Electric Fields ◽  
Density Functional ◽  
Local Density ◽  
Bayesian Optimization ◽  
Hybrid Functional ◽  
Electronic Band ◽  
Functional Theory ◽  
Hubbard U ◽  
Electronic Band Structures ◽  
Standard Density

In this study, we undertake a Bayesian optimization of the Hubbard U parameters of wurtzite GaN and InN. The optimized Us are then tested within the Hubbard-corrected local density approximation (LDA+U) approach against standard density functional theory, as well as a hybrid functional (HSE06). We present the electronic band structures of wurtzite GaN, InN, and (1:1) InGaN superlattice. In addition, we demonstrate the outstanding performance of the new parametrization, when computing the internal electric-fields in a series of [InN]1–[GaN]n superlattices (n = 2–5) stacked up along the c-axis.

A Rare Low Spin Co(IV) Bis-Silyldiamide with High Thermal Stability: Exploring the Origin of an Unusual S = 1/2 Configuration

2020 ◽  
Author(s):  
David Zanders ◽  
Goran Bačić ◽  
Dominique Leckie ◽  
Oluwadamilola Odegbesan ◽  
Jeremy M. Rawson ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Density Functional ◽  
Atomic Layer ◽  
Epr Spectrum ◽  
Functional Theory ◽  
Cluster Calculations ◽  
Layer Deposition ◽  
Starting Point ◽  
Higher Spin ◽  
Surface Saturation

Attempted preparation of a chelated Co(II) β-silylamide re-sulted in the unprecedented disproportionation to Co(0) and a spirocyclic cobalt(IV) bis(β-silyldiamide): [Co[(NtBu)2SiMe2]2] (1). Compound 1 exhibits a room temperature magnetic moment of 1.8 B.M and a solid state axial EPR spectrum diagnostic of a rare S = 1/2 configuration. Semicanonical coupled-cluster calculations (DLPNO-CCSD(T)) revealed the doublet state was clearly preferred (–27 kcal/mol) over higher spin configurations for which density functional theory (DFT) showed no energetic preference. Unlike other Co(IV) complexes, 1 had remarkable thermal stability, and was demonstrated to form a stable self-limiting monolayer in initial atomic layer deposition (ALD) surface saturation tests. The ease of synthesis and high-stability make 1 an attractive starting point to begin investigating otherwise inaccessible Co(IV) intermediates and synthesizing new materials.

scholarly journals Defect Processes in Halogen Doped SnO2

2021 ◽  
Vol 11 (2) ◽  
pp. 551
Author(s):  
Petros-Panagis Filippatos ◽  
Nikolaos Kelaidis ◽  
Maria Vasilopoulou ◽  
Dimitris Davazoglou ◽  
Alexander Chroneos
Keyword(s):  
Electronic Properties ◽  
Tin Oxide ◽  
Density Functional ◽  
Structural Changes ◽  
High Dielectric Constant ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Optical And Electronic Properties ◽  
High Dielectric ◽  
Gap States

In the present study, we performed density functional theory calculations (DFT) to investigate structural changes and their impact on the electronic properties in halogen (F, Cl, Br, and I) doped tin oxide (SnO2). We performed calculations for atoms intercalated either at interstitial or substitutional positions and then calculated the electronic structure and the optical properties of the doped SnO2. In all cases, a reduction in the bandgap value was evident, while gap states were also formed. Furthermore, when we insert these dopants in interstitial and substitutional positions, they all constitute a single acceptor and donor, respectively. This can also be seen in the density of states through the formation of gap states just above the valence band or below the conduction band, respectively. These gap states may contribute to significant changes in the optical and electronic properties of SnO2, thus affecting the metal oxide’s suitability for photovoltaics and photocatalytic devices. In particular, we found that iodine (I) doping of SnO2 induces a high dielectric constant while also reducing the oxide’s bandgap, making it more efficient for light-harvesting applications.

Geometric, electronic properties of Au$_l$Pt$_m$ ($l$+$m$$\leqslant$10) clusters: A first-principles study

2021 ◽  
Author(s):  
Wei-Feng Xie ◽  
Hao-Ran Zhu ◽  
Shi-Hao Wei
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Inverse Design ◽  
Functional Theory ◽  
First Principles Study

The structural evolutions and electronic properties of Au$_l$Pt$_m$ ($l$+$m$$\leqslant$10) clusters are investigated by using the first$-$principles methods based on density functional theory (DFT). We use Inverse design of materials by...

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