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 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.

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.

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.

ELECTRONIC AND MAGNETIC PROPERTIES OF SILICENE AND SILICANE NANORIBBONS

2013 ◽  
Vol 02 (02) ◽  
pp. 1350011 ◽  
Author(s):  
KAI LI ◽  
ANNA SHIN HWA LEE ◽  
YONG-WEI ZHANG ◽  
HUI PAN
Keyword(s):  
Magnetic Properties ◽  
First Principles ◽  
Magnetic Moments ◽  
Ground States ◽  
Band Gaps ◽  
Metastable States ◽  
First Principles Calculations ◽  
Ribbon Width ◽  
Electronic And Magnetic Properties ◽  
Silicene Nanoribbons

In this paper, first-principles calculations are carried out to study the electronic and magnetic properties of silicene and silicane nanoribbons, with and without H -passivation at the edges. We predict that the armchair nanoribbons are nonmagnetic and semiconducting. Interestingly, the band gaps of armchair silicene nanoribbons show oscillating behavior as the ribbon width increases. When their edges are passivated with H atoms, However, the oscillating phase is reversed. The zigzag nanoribbons are anti-ferromagnetic and semiconducting in their ground states, except that the zigzag silicane nanoribbons with edges passivated by H atoms are nonmagnetic. The zigzag silicane nanoribbons with bare edges show the highest magnetic moments in their ground states. The band gaps of zigzag nanoribbons in their ground states decrease with the increment of width. The metastable states of zigzag silicene nanoribbons are ferromagnetic and metallic. The zigzag silicane nanoribbons with bare edges are ferromagnetic and semiconducting in their metastable states. The silicene/silicane nanoribbons with attractive functions, which are achievable by edge engineering or external fields, may be applied to spintronic technologies and nanodevices.

scholarly journals The role of intrinsic vacancy defects in the electronic and magnetic properties of Sr3SnO: a first-principles study

RSC Advances ◽  
2017 ◽  
Vol 7 (12) ◽  
pp. 6880-6888 ◽  
Author(s):  
Javaria Batool ◽  
Syed Muhammad Alay-e-Abbas ◽  
Adnan Ali ◽  
Khalid Mahmood ◽  
Shaheen Akhtar ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Thermodynamic Stability ◽  
First Principles ◽  
Stability Diagram ◽  
Vacancy Defects ◽  
Electronic And Magnetic Properties ◽  
O Vacancy ◽  
Formation Energies ◽  
Thermodynamic Stability Diagram

The thermodynamic stability diagram and formation energies of intrinsic vacancy defects in Sr3SnO. Sr and O vacancy containing Sr3SnO is non-magnetic, while ferromagnetism is achieved in Sn deficient Sr3SnO.

scholarly journals DFT based investigation of the structural, magnetic, electronic, and half-metallic properties of solid In1-xTixSb solutions

2021 ◽  
Vol 24 (4) ◽  
pp. 43704
Author(s):  
S. Amrani ◽  
M. Berber ◽  
M. Mebrek
Keyword(s):  
Experimental Data ◽  
Magnetic Properties ◽  
Fermi Level ◽  
Spin Polarization ◽  
First Principles ◽  
Magnetic Moments ◽  
Ionic Character ◽  
Half Metallic ◽  
Electronic And Magnetic Properties ◽  
Substitutional Doping

With the intention to reveal the effect of the substitution, Ti-doped InSb alloy, we accomplished a first-principles prediction within the FPLAPW+lo method. We used GGA-PBEsol scheme attached with the improved TB-mBJ approach to predict structural, electronic, and magnetic properties of In1-xTixSb with concentration x=0, 0.125, 0.25, 0.50, 0.75, 0.875, and 1. Our lattice parameters are found in favorable agreement with the available theoretical and experimental data. The calculation shows that all structures are energetically stable. The substitutional doping transforms the ionic character of the InSb compound in half-metallic ferromagnetic comportment for concentration x = 0, 0.125, 0.25, and 0.50, with a spin polarization of 100% at the Fermi level, and metallic nature for In0.25Ti0.75Sb and In0.125Ti0.875Sb. The total magnetic moments are also estimated at about 1 mu;B. In0.875Ti0.125Sb, In0.75Ti0.25Sb, and In0.50Ti0.50Sb have half-metallic ferromagnets comportment and they can be upcoming applicants for spintronics applications.

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