scholarly journals Electronic Structure and Magnetism of Pristine, Defected, and Strained Ti2N MXene

2022 ◽  
Author(s):  
Yogendra Limbu ◽  
Gopi Chandra Kaphle ◽  
Alok Lal Karn ◽  
Niraj Kumar Shah ◽  
Durga Paudyal
Keyword(s):  
Electronic Structure ◽  
Band Structure ◽  
Fermi Level ◽  
Energy State ◽  
Ferromagnetic State ◽  
Max Phase ◽  
Strain Effect ◽  
High Symmetry ◽  
Electronic Band ◽  
Half Metallic

From first principles electronic structure calculations, we unravel the evolution of structural, electronic, and magnetic properties of pristine, defected, and strained titanium nitride MXene with different functional groups (-F, -O, -H, and -OH). The formation and cohesive energies reveal their chemical stability. The MAX phase and defect free functionalized MXenes are metallic except for oxygen terminated (Ti 2 NO 2 ) one which is 100% spin polarized half-metallic ferromagnet. The spin-orbit coupling significantly influences the bare MXene (Ti 2 N) to exhibit Dirac topology and band inversion near the high symmetry directions and Fermi level. The strain effect sways the Fermi level thereby shifting it toward lower energy state under compression and toward higher energy state under tensile strain in Ti 2 NH 2 . The Ti 2 NO 2 exhibits exotic electronic structure and magnetic states not only in pristine but also in strained and defected structures. Its half-metallic nature changes to semi-metallic under 1% compression and it is completely destroyed under 2% compression. In single vacancy defect, its band structure remarkably transforms from half-metallic to semi-conducting with large band gap in 12.5% Ti, weakly semi-conducting in 5.5% Ti, and semi-metallic in 12.5% O. The 25% N defect changes it’s half-metallic characteristic to metallic. Further, the 12.5% Co substitution preserves it’s half-metallic character, whereas Mn substitution allows it to convert half-metallic characteristic into weak semi-metallic characteristic preserving ferromagnetism. However, Cr substitution converts half-metallic ferromagnetic state to half-metallic anti-ferromagnetic state. The understanding made here on collective structural stability, and electronic band structure, and magnetic phenomena in novel 2D Ti 2 N derived MXenes open up their possibility in designing them for synthesis and thereby taking to applications.

scholarly journals Unraveling Electronic Structure, Magnetic States, and Topological Phenomena in Pristine, Defected, and Strained Ti2N MXene

2021 ◽  
Author(s):  
Yogendra Limbu ◽  
Gopi Chandra Kaphle ◽  
Alok Lal Karn ◽  
Niraj Kumar Shah ◽  
Durga Paudyal
Keyword(s):  
Energy State ◽  
Ferromagnetic State ◽  
Vacancy Defect ◽  
Max Phase ◽  
Strain Effect ◽  
Single Vacancy ◽  
Half Metallic ◽  
Topological Features ◽  
Metallic Ferromagnet ◽  
Magnetic States

We unravel the evolution of structural, electronic, magnetic, and topological properties of graphene-like pristine, defected, and strained titanium nitride MXene with different functional groups (-F, -O, -H, and -OH) employing first-principles calculations. The formation and cohesive energies reveal their chemical stability. The MAX phase and defect free functionalized MXenes are metallic in nature except for oxygen terminated one, which is 100% spin polarized half-metallic. Additionally, the bare MXene is nearly half-metallic ferromagnet. The spin-orbit coupling significantly influences the bare MXene possessing band inversion. The strain effect sways the Fermi level thereby shifting it toward lower energy state under compression and toward higher energy state under tensile strain in Ti2NH2. These properties are reversed in Ti2N, Ti2NF2, and Ti2N(OH)2. The half-metallic nature changes to semi-metallic under 1% compression and is completely destroyed under 2% compression. In single vacancy defect, the band structure of Ti2NO2 remarkably transforms from half-metallic to semi-conducting (with large band gap of 1.73 eV) in 12.5% Ti, weakly semi-conducting in 5.5% Ti, and topological semi-metal in 12.5% oxygen. The 25% N defect changes the half-metallic to the metallic with certain topological features. Further, the 12.5% Co substitution in Ti2NO2 preserves the half-metallic character, whereas Mn substitution allows to convert half-metallic into weak semi-metallic preserving ferromagnetic character. However, Cr substitution converts half-metallic ferromagnetic to half-metallic anti-ferromagnetic state. The understanding made here on collective structural stability, and magnetic and topological phenomena in novel 2D MXenes open up their possibility in designing them for synthesis and thereby taking to applications.

Magnetic Ground State and Electronic Structure Calculations of PbMnO3 Using DFT

2014 ◽  
Vol 895 ◽  
pp. 420-423 ◽  
Author(s):  
Sathya Sheela Subramanian ◽  
Baskaran Natesan
Keyword(s):  
Electronic Structure ◽  
Band Structure ◽  
Fermi Level ◽  
Ground State ◽  
Density Functional ◽  
Electronic Structure Calculations ◽  
Magnetic Ground State ◽  
Electronic Band ◽  
Structure Calculations ◽  
Centrosymmetric Structure

Structural optimization, magnetic ground state and electronic structure calculations of tetragonal PbMnO3have been carried out using local density approximation (LDA) implementations of density functional theory (DFT). Structural optimizations were done on tetragonal P4mm (non-centrosymmetric) and P4/mmm (centrosymmetric) structures using experimental lattice parameters and our results indicate that P4mm is more stable than P4/mmm. In order to determine the stable magnetic ground state of PbMnO3, total energies for different magnetic configurations such as nonmagnetic (NM), ferromagnetic (FM) and antiferromagnetic (AFM) were computed for both P4mm and P4/mmm structures. The total energy results reveal that the FM non-centrosymmetric structure is found to be the most stable magnetic ground state. The electronic band structure, density of states (DOS) and the electron localization function (ELF) were calculated for the stable FM structure. ELF revealed the distorted non-centrosymmetric structure. The band structure and DOS for the majority spins of FM PbMnO3showed no band gap at the Fermi level. However, a gap opens up at the Fermi level in minority spin channel suggesting that it could be a half-metal and a potential spintronic candidate.

Structural and Magnetic Study on the Effect of Substitution of Cobalt by d-Valent Elements of Co2FeSi Heusler Alloy

2016 ◽  
Vol 708 ◽  
pp. 37-41
Author(s):  
Muhammad Noor Syazwan Saimin ◽  
Siti Sumaiyah Sheikh Abdul Aziz ◽  
A.M.M. Ali ◽  
Oskar Hasdinor Hassan ◽  
Muhd Zu Azhan Yahya ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
Band Structure ◽  
Fermi Level ◽  
Density Of States ◽  
Magnetic Moment ◽  
Local Magnetic Moment ◽  
Half Metallic ◽  
New States ◽  
Full Heusler

In this paper, the effect of substitution of Co by d-valent elements such as Ag and Pt on electronic structure and magnetic properties of full Heusler type Co2FeSi alloys was investigated. Structural study reveals the presence of a small gap in the minority band structure around the vicinity of the Fermi level on Co2FeSi resulting to half-metallic behaviour. However, CoFeSiAg and CoFeSiPt cannot preserved the half-metalicity due to disappearing of the gap in the minority band structure due to the creation of new states around the Fermi level in the minority density of states. The variation in the magnetic moment of Co2FeSi with change of the atoms was attributed to the change in the local magnetic moment of atoms.

scholarly journals An ab-initio study on structural, elastic, electronic, bonding, thermal, and optical properties of topological Weyl semimetal TaX (X = P, As)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. I. Naher ◽  
S. H. Naqib
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Fermi Level ◽  
Density Of States ◽  
Electronic Band Structure ◽  
Optical Parameters ◽  
Electronic Density ◽  
Electronic Band ◽  
Wide Range ◽  
Weyl Semimetals

AbstractIn recent days, study of topological Weyl semimetals have become an active branch of physics and materials science because they led to realization of the Weyl fermions and exhibited protected Fermi arc surface states. Therefore, topological Weyl semimetals TaX (X = P, As) are important electronic systems to investigate both from the point of view of fundamental physics and potential applications. In this work, we have studied the structural, elastic, mechanical, electronic, bonding, acoustic, thermal and optical properties of TaX (X = P, As) in detail via first-principles method using the density functional theory. A comprehensive study of elastic constants and moduli shows that both TaP and TaAs possesses low to medium level of elastic anisotropy (depending on the measure), reasonably good machinability, mixed bonding characteristics with ionic and covalent contributions, brittle nature and relatively high Vickers hardness with a low Debye temperature and melting temperature. The minimum thermal conductivities and anisotropies of TaX (X = P, As) are calculated. Bond population analysis supports the bonding nature as predicted by the elastic parameters. The bulk electronic band structure calculations reveal clear semi-metallic features with quasi-linear energy dispersions in certain sections of the Brillouin zone near the Fermi level. A pseudogap in the electronic energy density of states at the Fermi level separating the bonding and the antibonding states indicates significant electronic stability of tetragonal TaX (X = P, As).The reflectivity spectra show almost non-selective behavior over a wide range of photon energy encompassing visible to mid-ultraviolet regions. High reflectivity over wide spectral range makes TaX suitable as reflecting coating. TaX (X = P, As) are very efficient absorber of ultraviolet radiation. Both the compounds are moderately optically anisotropic owing to the anisotropic nature of the electronic band structure. The refractive indices are very high in the infrared to visible range. All the energy dependent optical parameters show metallic features and are in complete accord with the underlying bulk electronic density of states calculations.

Synthesis, crystal and electronic structure of BaLi2Cd2Ge2

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sviatoslav Baranets ◽  
Alexander Ovchinnikov ◽  
Svilen Bobev
Keyword(s):  
Crystal Structure ◽  
Electronic Structure ◽  
Fermi Level ◽  
Structure Type ◽  
Layered Crystal ◽  
Electronic Density ◽  
Electronic Band ◽  
Cell Parameters ◽  
Layered Crystal Structure ◽  
Electronic Band Gap

Abstract A new quaternary germanide has been synthesized and structurally characterized. BaLi2Cd2Ge2 adopts the rhombohedral CaCu4P2 structure type (Pearson code hR7; space group R 3 ‾ m $R‾{3}m$ , Z = 3) with unit cell parameters a = 4.5929(6) and c = 26.119(5) Å. Structure refinements from single-crystal X-ray diffraction data demonstrate that the layered crystal structure can be regarded as an ordered quaternary variant of the ternary archetype; structural parallels to layered pnictides and binary germanides can also be drawn. The layered crystal structure is characterized by the absence of direct Ge–Ge and Cd–Cd homoatomic bonds, which suggests that BaLi2Cd2Ge2 should be classified as a Zintl phase, according to the formulation (Ba2+)(Li+)2(Cd2+)2(Ge4−)2. Electronic structure calculations show that the Fermi level crosses a distinct peak in the DOS, although the presence of an electronic band gap or a dip in the electronic density of states at the Fermi level is expected based on the electron partitioning.

scholarly journals Electronic stripes and transport properties in borophene heterostructures

Nanoscale ◽  
2019 ◽  
Vol 11 (38) ◽  
pp. 17894-17903 ◽  
Author(s):  
G. H. Silvestre ◽  
Wanderlã L. Scopel ◽  
R. H. Miwa
Keyword(s):  
Band Structure ◽  
Fermi Level ◽  
Transport Properties ◽  
Electronic Band Structure ◽  
Electronic States ◽  
Electronic Band

(Left) Localization of the electronic states near the Fermi level, and the electronic band structure projected on the S1 and S2 stripes. (Right) Transmission probabilites parallel (y) and perpendicular (x) to the S1/S2 borophene superlattice.

Electronic Structure and Ferromagnetic Properties of Doped Calcium Sulfide Ca1−xTMxS (TM = V, Cr and Co)

SPIN ◽  
2020 ◽  
Vol 10 (02) ◽  
pp. 2050013 ◽  
Author(s):  
Amina Aiche ◽  
Abdelkader Tadjer ◽  
Hadj Moulay Ahmed Mazouz ◽  
Bendouma Doumi ◽  
Houari Khachai
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
Density Functional ◽  
Double Exchange ◽  
Ferromagnetic State ◽  
Spin Splitting ◽  
Full Potential ◽  
Generalized Gradient ◽  
Metallic Behavior ◽  
Half Metallic

The electronic structure and magnetic properties of diluted Ca[Formula: see text]TMxS (TM[Formula: see text][Formula: see text][Formula: see text]V, Cr and Co) in the rocksalt structure at concentrations [Formula: see text], 0.125 and 0.25 were studied using the full-potential linearized augmented plane wave approximation of the density functional theory with the Wu-Cohen generalized gradient approximation (WC-GGA) and the Tran–Blaha-modified Becke–Johnson (TB-mBJ) potential. Features such as lattice constant, bulk modulus, spin-polarized band structures, total and local densities of states and magnetic properties have been computed. The electronic structure show that Ca[Formula: see text](V, Cr)xS at all the studied concentrations and the diluted Ca[Formula: see text]CoxS with [Formula: see text] compounds are half-metallic ferromagnets with spin polarization of 100%. The calculated total magnetic moments for Ca[Formula: see text]VxS and Ca[Formula: see text]CoxS show the same integer value of 3[Formula: see text][Formula: see text] per formula unit and Ca[Formula: see text]CrxS exhibit a total magnetic moment of 4[Formula: see text][Formula: see text], which confirm the half-metallic behavior of these compounds. We also calculated the values of the band edge spin splitting of the valence and conduction bands and the exchange constants. We have found that the ferromagnetic state is stable by the p-d exchange associated with the double-exchange mechanism. The diluted Ca[Formula: see text](V,Cr,Co)xS are found to be new promising candidates for spintronic applications.

Energy band alignment at the heterointerface between a nanostructured TiO2 layer and Au22(SG)18 clusters: relevance to metal-cluster-sensitized solar cells

Nanoscale ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 175-184
Author(s):  
Liudmila L. Larina ◽  
Oleksii Omelianovych ◽  
Van-Duong Dao ◽  
Kyunglim Pyo ◽  
Dongil Lee ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Solar Cells ◽  
Band Structure ◽  
Electronic Band Structure ◽  
Metal Cluster ◽  
Band Alignment ◽  
Tio2 Layer ◽  
Electronic Band ◽  
Xps Study ◽  
Sensitized Solar Cells

XPS study of the electronic structure of the Au22(SG)18 clusters and their interface with TiO2 reveals that tailoring of the electronic band structure at the interface can be exploited to increase the efficiency of metal-cluster-sensitized solar cells.

First Principles Calculations of Graphene Doped with Al, P and Si Heteroatoms

2017 ◽  
Vol 16 ◽  
pp. 52-55 ◽  
Author(s):  
Maria Teresa Romero ◽  
Yuliana Avila Alvarado ◽  
Reyes Garcia-Diaz ◽  
Carlos Rodriguez Garcia ◽  
Raul Ochoa Valiente ◽  
...  
Keyword(s):  
Band Structure ◽  
Fermi Level ◽  
Density Functional ◽  
Pristine Graphene ◽  
High Symmetry ◽  
Linear Dispersion ◽  
Graphene Layers ◽  
Doping Effects ◽  
Semiconductor Behavior ◽  
Quantum Espresso

In this work, studies of the doping effects on the electronic and structural properties of graphene were performed. Calculations have been done within the periodic density functional theory (DFT) as implemented in PWscf code of the Quantum Espresso Package. Graphene layers have been modeled using the 4x4 periodic supercells. The doping is explored considering phosphorus (P), aluminum (Al) and silicon (Si) heteroatoms. One heteroatom per supercell was considered. Electronic structure results show that the pristine graphene has a linear dispersion at high symmetry K point and zero gap. Band structure of graphene doped with Al atoms exhibit a metal behavior since a valence band crosses the Fermi level. Graphene doped with P also presents a metal behavior but in this case a conduction band crosses the Fermi level. In addition, when the dopant is Si the band structure shows a semiconductor behavior with a 0.3 eV gap. In all cases, the zero gap energy characteristic of graphene was changed by dopant heteroatom. The Dirac lineal dispersion relation is preserved only in the pristine graphene.

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