scholarly journals Structural, Electronic and Magnetic Properties of Defected Water Adsorbed Single-Layer MoS2

2021 ◽  
Vol 26 (1) ◽  
pp. 43-50
Author(s):  
Hari Krishna Neupane ◽  
Narayan Prasad Adhikari
Keyword(s):  
Magnetic Properties ◽  
Band Structure ◽  
Density Of States ◽  
Density Functional ◽  
Single Layer ◽  
Vacancy Defect ◽  
Partial Density ◽  
Energy Bands ◽  
Vacancy Defects ◽  
Electronic And Magnetic Properties

Water adsorbed in MoS2 (wad-MoS2), 1S atom vacancy defect in wad-MoS2 (1S-wad-MoS2), 2S atoms vacancy defects in wad-MoS2 (2S-wad-MoS2), and 1Mo atom vacancy defect in wad-MoS2 (Mo-wad-MoS2) materials were constructed, and their structural, electronic, and magnetic properties were studied by spin-polarized density functional theory (DFT) based first-principles calculations. The wad-MoS2, 1S-wad-MoS2, 2S-wad-MoS2, and Mo-wad-MoS2 materials were found stable. From band structure calculations, wad-MoS2, 1S-wad-MoS2 and 2S-wad-MoS2 materials open energy bandgap of values 1.19 eV, 0.65 eV and 0.38 eV respectively. Also, it was found that the conductivity strength of the material increases with an increase in the concentration of S atom vacancy defects in the structure. On the other hand, the Mo-wad-MoS2 material has metallic properties because energy bands of electrons crossed the Fermi energy level in the band structure. For the investigation of magnetic properties, the density of states (DoS) and partial density of states (PDoS) calculations were used and found that wad-MoS2, 1S-wad-MoS2, and 2S-wad-MoS2 are non-magnetic materials, while Mo-wad-MoS2 is a magnetic material. The total magnetic moment of Mo-wad-MoS2 has a value of 2.66 µB/cell, due to the arrangement of unpaired up-spin and down-spin of electrons in 3s & 3p orbitals of S atoms; and 4p, 4d & 5s orbitals of Mo atoms in the material.

Electronic and magnetic properties of defected MoS2 monolayer

BIBECHANA ◽  
2021 ◽  
Vol 18 (2) ◽  
pp. 68-79
Author(s):  
Hari Krishna Neupane ◽  
Narayan Prasad Adhikari
Keyword(s):  
Magnetic Properties ◽  
Magnetic Moment ◽  
Density Functional ◽  
2D Materials ◽  
Dft Method ◽  
Vacancy Defect ◽  
Energy Bands ◽  
Band Structures ◽  
Vacancy Defects ◽  
Electronic And Magnetic Properties

It is interesting to understand the effect of defects in 2D materials because vacancy defects in 2D materials have novel electronic and magnetic properties. In this work, we studied electronic and magnetic properties of 1S vacancy defect (1Sv-MoS2), 2S vacancy defects (2Sv-MoS2), 1Mo vacancy defect (Mov-MoS2), and (1Mo & 1S) vacancy defects ((Mo-S)v-MoS2) in 2D MoS2 material by first-principles calculations within spin-polarized density functional theory (DFT) method. To understand the electronic properties of materials, we have analyzed band structures and DOS calculations and found that 1Sv-MoS2 & 2Sv-MoS2 materials have semiconducting nature. This is because, 1Sv-MoS2 & 2Sv-MoS2 materials open a small energy band gap of values 0.68 eV & 0.54 eV respectively in band structures. But, in Mov-MoS2 & (Mo-S)v-MoS2 materials, energy bands around the Fermi level mix with the orbital’s of Mo and S atoms. As a result, bands are split and raised around and above the Fermi energy level. Therefore, Mov-MoS2 & (Mo-S)v-MoS2 materials have metallic nature. We found that MoS2, 1Sv-MoS2 & 2Sv-MoS2 materials have non-magnetic properties, and Mov-MoS2 & (Mo-S)v-MoS2 materials have magnetic properties because magnetic moment of MoS2, 1Sv-MoS2 & 2Sv-MoS2 materials have 0.00 µB/cell value and Mov-MoS2 & (Mo-S)v-MoS2 materials have 2.72 µB/cell & 0.99 µB/cell  respectively. Therefore, non-magnetic MoS2 changes to magnetic Mov-MoS2 & (Mo-S)v-MoS2 materials due to Mo and (1Mo & 1S) vacancy defects.  The magnetic moment obtained in Mov-MoS2 & (Mo-S)v-MoS2 materials due to the distribution of up and down spins in 4p, 4d & 5s orbitals of  Mo atoms and 3s & 3p orbitals of S atoms in structures. The significant values of the magnetic moment are given by distributed spins in 4d orbital of Mo atoms and 3p orbital of S atoms. BIBECHANA 18 (2) (2021) 68-79  

scholarly journals Tuning Structural, Electronic, and Magnetic Properties of C Sites Vacancy Defects in Graphene/MoS2 van der Waals Heterostructure Materials: A First-Principles Study

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Hari Krishna Neupane ◽  
Narayan Prasad Adhikari
Keyword(s):  
Magnetic Properties ◽  
Band Structure ◽  
Density Of States ◽  
First Principles ◽  
Magnetic Moments ◽  
Van Der Waals ◽  
Partial Density ◽  
Vacancy Defects ◽  
Electronic And Magnetic Properties ◽  
Structure Density

In this work, we systematically studied the structure, and electronic and magnetic properties of van der Waals (vdWs) interface Graphene/MoS2 heterostructure (HS-G/MoS2) and C sites vacancy defects in HS-G/MoS2 materials using first-principles calculations. By the structural analysis, we found that nondefects geometry is more compact than defects geometries. To investigate the electronic and magnetic properties of HS-G/MoS2 and C sites vacancy defects in HS-G/MoS2 materials, we have studied band structure, density of states (DOS), and partial density of states (PDOS). By analyzing the results, we found that HS-G/MoS2 is metallic in nature but C sites vacancy defects in HS-G/MoS2 materials have a certain energy bandgap. Also, from the band structure calculations, we found that Fermi energy level shifted towards the conduction band in vacancy defects geometries which reveals that the defected heterostructure is n-type Schottky contacts. From DOS and PDOS analysis, we obtained that the nonmagnetic HS-G/MoS2 material changes to magnetic materials due to the presence of C sites vacancy defects. Right 1C atom vacancy defects (R-1C), left 1C atom vacancy defects (L-1C), centre 1C atom vacancy defects (C-1C), and 2C (1C right and 1C centre) atom vacancy defects in HS-G/MoS2 materials have magnetic moments of −0.75 µB/cell, −0.75 µB/cell, −0.12 µB/cell, and +0.39 µB/cell, respectively. Electrons from 2s and 2p orbitals of C atoms have main contributions for the magnetism in all these materials.

scholarly journals First-principles study of C cites vacancy defects in water adsorbed Graphene

2020 ◽  
pp. 19-29
Author(s):  
Hari Krishna Neupane ◽  
Narayan Prasad Adhikari
Keyword(s):  
Magnetic Properties ◽  
Band Gap ◽  
Density Of States ◽  
Magnetic Moment ◽  
First Principles ◽  
Density Functional ◽  
Partial Density ◽  
Dangling Bonds ◽  
Graphene Surface ◽  
Vacancy Defects

 The electronic and magnetic properties of water adsorbed graphene (wad – G), single carbon (1C) atom vacancy defects in water adsorbed graphene (1Catom-vacancy – wad – G) and double carbon (2C) atoms vacancy defects in water adsorbed graphene (2Catom-vacancy – wad – G) materials are studied by first-principles calculations within the frame work of density functional theory (DFT) using computational tool Quantum ESPRESSO (QE) code. We have calculated the binding energy of wad – G, 1Catom-vacancy – wad – G and 2Catom-vacancy – wad – G materials, and then found that non-defects geometry is more compact than vacancy defects geometries. From band structure calculations, we found that wad – G is zero band gap semiconductor, but 1Catom-vacancy – wad – G and, 2Catom-vacancy – wad – G materials have metallic properties. Hence, zero band gap semiconductor changes to metallic nature due to C sites vacancy defects in its structures. We have investigated the magnetic properties of wad – G and its C sites vacancy defects materials by using Density of States (DOS) and Partial Density of States (PDOS) calculations. We found that wad – G is non- magnetic material. 1C atom vacancy defects in graphene surface of wad – G is induced magnetization by the re-bonding of two dangling bonds and acquiring significant magnetic moment (0.11 µB/ cell) through remaining unsaturated dangling bond. But, 2C atoms vacancy defects in graphene surface of wad – G induced low value of magnetic moment (+0.03 µB/ cell) than 1C atom vacancy defects in structure, which is due to no dangling bonds present in the structure. Therefore, non-magnetic, wad – G changes to magnetic, 1Catom-vacancy – wad – G and, 2Catom-vacancy – wad – G materials due to C sites vacancy defects in wad – G structure. The 2p orbital of carbon atoms has main contribution of magnetic moment in defects structures.

scholarly journals First-Principles Study of Vacancy and Impurities Defects in Graphene

2021 ◽  
Vol 2 (01) ◽  
pp. 93-102
Author(s):  
Hari Krishna Neupane ◽  
Narayan Prasad Adhikari
Keyword(s):  
Magnetic Properties ◽  
Energy Level ◽  
Density Of States ◽  
Fermi Energy ◽  
First Principles ◽  
Density Functional ◽  
Partial Density ◽  
Fermi Energy Level ◽  
Vacancy Defects ◽  
Impurity Defects

In this work, we have studied the electronic and magnetic properties of 1C atom vacancy defects in graphene (1Cv-d-G), 1N atom impurity defects in graphene (1NI-d-G) and 1O atom impurity defects in graphene (1OI-d-G) materials through first principles calculations based on spin-polarized density functional theory (DFT) method, using computational tool Quantum ESPRESSO (QE) code. From band structure and density of states (DOS) calculations, we found that supercell structure of monolayer graphene is a zero bandgap material. But, electronic bands of 1Cv-d-G, 1NI-d-G and 1OI-d-G materials split around the Fermi energy level and DOS of up & down spins states appear in the Fermi energy level. Thus, 1Cv-d-G, 1NI-d-G and 1OI-d-G materials have metallic properties. We have studied the magnetic properties of pure and defected materials by analyzing density of states (DOS) and partial density of states (PDOS) calculations. We found that graphene and 1OI-d-G materials have non-magnetic properties. On the other hand, 1C vacancy atom and 1N impurity atom induced magnetization in 1Cv-d-G & 1NI-d-G materials by the rebonding of dangling bonds and acquiring significant magnetic moments of values -0.75μB/cell & 0.05μB/cell respectively through remaining unsaturated dangling bond. Therefore, non-magnetic graphene changes to magnetic 1Cv-d-G and 1NI-d-G materials due to 1C atom vacancy defects and 1N atom impurity defects. The 2p orbital of carbon atoms has main contribution of magnetic moment in these defected structures.

scholarly journals First-Principles Study of Electronic and Magnetic Properties of Anatase and its Role in Anatase-Mxene Nanocomposite

2019 ◽  
Vol 5 (1) ◽  
pp. 42-53
Author(s):  
D. Parajuli ◽  
G. C. Kaphle ◽  
K. Samatha
Keyword(s):  
Magnetic Properties ◽  
Band Structure ◽  
Charge Density ◽  
Density Of States ◽  
Density Functional ◽  
Tight Binding ◽  
Total Density ◽  
Energy Storage Devices ◽  
Orbital Contribution ◽  
Electronic And Magnetic Properties

The electronic and magnetic properties of Titanium and one of its oxide Anatase are calculated by using Tight Binding Linear Muffin-Tin Orbital Atomic Sphere Approximation (TB-LMTO-ASA) method under Density Functional Theory (DFT). The lattice parameter, band structure, Density of States (DOS) and charge density distributions of Ti and TiO2 (Anatase) required for electronic structure are calculated respectively. The orbital contribution is analyzed by fat band structure; the d- orbital on conduction band and, s and p orbitals on valance bands. Consequently, their magnetic properties are checked. From our study, we found that the magnetic moments of Ti and TiO2 are found to be 2.2 μB and 0 respectively. The total Density of States for spin up and down electron have smaller difference in Ti and symmetric in TiO2 indicates that Ti slightly paramagnetic and Anatase is non magnetic in nature. The charge density plots reveals the concentration of electrons at the site under study. Anatase can be deposited onto Mxene to form Mxene-Anatase nanocomposite which has several excellent applications in the field of biosensors, biocompatible materials, energy storage devices, topological insulators etc.

scholarly journals The effect of pressure and alloying on half-metallicity of quaternary Heusler compounds CoMnYZ (Z = Al, Ga, and In)

2016 ◽  
Vol 34 (4) ◽  
pp. 905-915 ◽  
Author(s):  
M. Rahmoune ◽  
A. Chahed ◽  
A. Amar ◽  
H. Rozale ◽  
A. Lakdja ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Heusler Alloys ◽  
Band Gaps ◽  
Ferromagnetic Behavior ◽  
Full Potential ◽  
Energy Bands ◽  
Half Metallicity ◽  
Half Metallic ◽  
Electronic And Magnetic Properties

AbstractIn this work, first-principles calculations of the structural, electronic and magnetic properties of Heusler alloys CoMnYAl, CoMnYGa and CoMnYIn are presented. The full potential linearized augmented plane waves (FP-LAPW) method based on the density functional theory (DFT) has been applied. The structural results showed that CoMnYZ (Z = Al, Ga, In) compounds in the stable structure of type 1+FM were true half-metallic (HM) ferromagnets. The minority (half-metallic) band gaps were found to be 0.51 (0.158), 0.59 (0.294), and 0.54 (0.195) eV for Z = Al, Ga, and In, respectively. The characteristics of energy bands and origin of minority band gaps were also studied. In addition, the effect of volumetric and tetragonal strain on HM character was studied. We also investigated the structural, electronic and magnetic properties of the doped Heusler alloys CoMnYGa1−xAlx, CoMnYAl1−xInx and CoMnYGa1−xInx (x = 0, 0.25, 0.5, 0.75, 1). The composition dependence of the lattice parameters obeys Vegard’s law. All alloy compositions exhibit HM ferromagnetic behavior with a high Curie temperature (TC).

Effect of strain on the electronic and magnetic properties of an Fe-doped WSe2 monolayer

RSC Advances ◽  
2016 ◽  
Vol 6 (74) ◽  
pp. 69758-69763 ◽  
Author(s):  
Xu Ma ◽  
Xu Zhao ◽  
Tianxing Wang
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
First Principles ◽  
Density Functional ◽  
Single Layer ◽  
Functional Theory ◽  
Electronic And Magnetic Properties

We investigate the electronic and magnetic properties of an Fe-doped single-layer WSe2 sheet with strain from −10% to 10% using first-principles methods based on density functional theory.

Structural, electronic and magnetic properties of S sites vacancy defects graphene/MoS2 van der Waals heterostructures: First-principles study

2021 ◽  
pp. 2150009
Author(s):  
Hari Krishna Neupane ◽  
Narayan Prasad Adhikari
Keyword(s):  
Magnetic Properties ◽  
Magnetic Moment ◽  
First Principles ◽  
Density Functional ◽  
Dominant Role ◽  
Van Der Waals ◽  
Schottky Contact ◽  
Unequal Distribution ◽  
Vacancy Defects ◽  
Electronic And Magnetic Properties

In this work, we investigated the geometrical structures, electronic and magnetic properties of S sites vacancy defects in heterostructure graphene/molybdenum disulphide ((HS)G/MoS[Formula: see text] material by performing first-principles calculations based on spin polarized Density Functional Theory (DFT) method within van der Waals (vdW) corrections (DFT-D2) approach. All the structures are optimized and relaxed by BFGS method using computational tool Quantum ESPRESSO (QE) package. We found that both (HS)G/MoS2 and S sites vacancy defects in (HS)G/MoS2 (D1S–(HS)G/MoS2, U1S–(HS)G/MoS2, 2S–(HS)G/MoS2 and 3S–(HS)G/MoS[Formula: see text] are stable materials, and atoms in defects structures are more compact than in pristine (HS)G/MoS2 structure. From band structure calculations, we found that (HS)G/MoS2, (D1S–(HS)G/MoS2, U1S–(HS)G/MoS2, 2S–(HS)G/MoS2 and 3S–(HS)G/MoS[Formula: see text] materials have [Formula: see text]-type Schottky contact. The Dirac cone is formed in conduction band of the materials mentioned above. The barrier height of Dirac cones from Fermi energy level of (HS)G/MoS2, (D1S–(HS)G/MoS2, U1S–(HS)G/MoS2, 2S–(HS)G/MoS2 and 3S–(HS)G/MoS[Formula: see text] materials have values 0.56[Formula: see text]eV, 0.62[Formula: see text]eV, 0.62[Formula: see text]eV, 0.64[Formula: see text]eV and 0.65[Formula: see text]eV, respectively, which means they have metallic properties. To study the magnetic properties of materials, we have carried out DoS and PDoS calculations. We found that (HS)G/MoS2, D1S–(HS)G/MoS2 and U1S–(HS)G/MoS2 materials have non-magnetic properties, and 2S–(HS)G/MoS2 and 3S–(HS)G/MoS2 materials have magnetic properties. Therefore, the non-magnetic (HS)G/MoS2 changes to magnetic 2S–(HS)G/MoS2 and 3S–(HS)G/MoS2 materials due to 2S and 3S atoms vacancy defects, respectively, in (HS)G/MoS2 material. Magnetic moment obtained in 2S–(HS)G/MoS2 and 3S–(HS)G/MoS2 materials due to the unequal distribution of up and down spin states of electrons in 2s and 2p orbitals of C atoms; 4p, 4d and 5s orbitals of Mo atoms; and 3s and 3p orbitals of S atoms in structures. Magnetic moment of 2S–(HS)G/MoS2 and 3S–(HS)G/MoS2 materials is −0.11[Formula: see text][Formula: see text]/cell and [Formula: see text]/cell, respectively, and spins of 2p orbital of C atoms, 3p orbital of S atoms and 4d orbital of Mo atoms have dominant role to create magnetism in 2S–(HS)G/MoS2 and 3S–(HS)G/MoS2 materials.

Study on the Energy Band Structure of La Doped ZnO

2011 ◽  
Vol 233-235 ◽  
pp. 2119-2124
Author(s):  
Xiao Qing Liu ◽  
Rui Fang Zhang ◽  
Yi Guo Su ◽  
Xiao Jing Wang
Keyword(s):  
Band Structure ◽  
Conduction Band ◽  
Energy Band ◽  
Density Functional ◽  
Energy Band Structure ◽  
Partial Density ◽  
Energy Bands ◽  
Doped Zno ◽  
Zno Crystal ◽  
La Doped

The energy bands of La -doped ZnO were studied systematically by the density functional theory (DFT). Based on the data of the band structure, DOS (Density of State) and PDOS( Partial Density of States), atomic populations and net charge, the influence on the energy band structure of the macrostructure of ZnO and La-doped ZnO was investigated. The results showed that the free electrons were produced by the doping of La on (or in) ZnO crystal. The Fermi energy was shifted up to the conduction band, making the ZnO particles having the characters of degenerated semiconductor. The excitation from impurity states to the conduction band may account for the blue shift of the absorption edge in the model of La-doped ZnO. Comparison with the different models of the La doped/loaded on the ZnO surface, La atoms loaded on the surface of ZnO and La atoms replaced of Zn atoms on the ZnO surface, the shift to the lower energy location were found after La doping/loading. The more shift and the large band gap was found for the model of La doped on the Zn position in the ZnO crystal.

scholarly journals Single layer PbI2: hydrogenation-driven reconstructions

RSC Advances ◽  
2016 ◽  
Vol 6 (92) ◽  
pp. 89708-89714 ◽  
Author(s):  
C. Bacaksiz ◽  
H. Sahin
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Hydrogen Atom ◽  
Density Functional ◽  
Single Layer ◽  
Functional Theory ◽  
Electronic And Magnetic Properties

By performing density functional theory-based calculations, we investigate how a hydrogen atom interacts with the surfaces of monolayer PbI2 and how one- and two-side hydrogenation modifies its structural, electronic, and magnetic properties.

Sign in / Sign up

Export Citation Format

Share Document