scholarly journals Ab-initio study of the orthorhombic ndmno3 perovskite

2014 ◽  
Vol 70 (a1) ◽  
pp. C1806-C1806
Author(s):  
Samir Bentata ◽  
Bouabdellah Bouadjemi ◽  
Tayeb Lantri ◽  
Wissem Benstaali
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Total Density ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Functional Theory ◽  
Half Metallic ◽  
Generalized Gradient Approximation ◽  
Ferromagnetic Ground State ◽  
Total Density Of States

We investigate the structural, electronic and magnetic properties of the orthorhombic Perovskite oxyde NdMnO3 through density-functional-theory (DFT) calculations using both generalized gradient approximation GGA+U, where U is on-site Coulomb interaction correction. The electronic band structure, the partial and total density of states (DOS) and the magnetic moment are determined. The results show a half-metallic ferromagnetic ground state for the orthorhombic NdMnO3.

An Investigation of Half-Metallic Ferromagnets Behavior in Hg2CuTi-Type Heusler Alloy Ti2FeAl by Using GGA

2012 ◽  
Vol 535-537 ◽  
pp. 1291-1294 ◽  
Author(s):  
Xiu De Yang ◽  
Bo Wu ◽  
Song Zhang
Keyword(s):  
Density Functional Theory ◽  
Heusler Alloy ◽  
Density Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Half Metallic ◽  
Generalized Gradient Approximation ◽  
Indirect Exchange ◽  
The Density Functional Theory ◽  
Direct Hybridization

By using generalized gradient approximation (GGA) scheme within the density functional theory (DFT), the electronic and magnetic properties of Hg2CuTi-type Heusler alloy Ti2FeAl were investigated. The results reveal that a 100% spin polarization appears at Fermi level (εF) in Ti2FeAl, and is maintained during lattice range of 5.1Å~6.2Å. Ti2FeAl is one of stable Half-Metallic Ferromagnets (HMF) with a spin-minority gap of 0.5 eV at εF and total magnetic moment of 1μB per unit cell. Our studies also indicate that the competition between RKKY-type indirect exchange and direct hybridization of d-electronic atoms plays a dominating role in determining the magnetism.

scholarly journals Electronic structure, Mechanical and Thermodynamic properties of CoYSb (Y= Cr, Mo, W) half-Heusler compounds as potential spintronic materials

2021 ◽  
Author(s):  
O. T. Uto ◽  
J. O. Akinlami ◽  
S. Kenmoe ◽  
G. A. Adebayo
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Structural Phase ◽  
Covalent Bond ◽  
Stable Phase ◽  
Type I ◽  
Generalized Gradient ◽  
Electronic Density ◽  
Electronic Band ◽  
Half Metallic

Abstract The CoYSb (Y = Cr, Mo and W) compounds which are XYZ type half-Heusler alloys and also exist in the face centred cubic MgAgAs-type struc-ture conform to F ̄43m space group. In the present work, these compoundsare investigated in different atomic arrangements called, Type-I, Type-II andType-III phases, using Generalized Gradient Approximation (GGA) in the Density Functional Theory (DFT) implemented in QE (Quantum EspressoAb-Initio Simulation Package). The ferromagnetic state of these alloys is studied after investigating their stable structural phase. The calculated electronic band structure and the total electronic density of states indicated nearly half-metallic behaviour in CoMoSb with a possibility of being used in spintronic application, metallic in CoWSb and half-metallic in CoCrSb, with the minority spin band gap of 0.81 eV. Furthermore, the calculated mechanical properties predicted an anisotropic behaviour of these alloys in the stable phase. Finally, due to its high Debye temperature value, CoCrSb possesses a stronger covalent bond than CoMoSb and CoWSb, respectively.

Half-metallicity and optoelectronic properties of V-doped zincblende ZnS and CdS alloys

2016 ◽  
Vol 30 (08) ◽  
pp. 1650034 ◽  
Author(s):  
Mohammed El Amine Monir ◽  
H. Baltache ◽  
R. Khenata ◽  
G. Murtaza ◽  
R. Ahmed ◽  
...  
Keyword(s):  
Magnetic Moment ◽  
Density Functional ◽  
Spin Exchange ◽  
Electronic Band Structure ◽  
Magnetic Behavior ◽  
Full Potential ◽  
Generalized Gradient ◽  
Half Metallicity ◽  
Electronic Band ◽  
Half Metallic

In this paper, spin-polarized density functional calculations on the structural, electronic, optical and magnetic properties of the zincblende structure of the [Formula: see text] and [Formula: see text] alloys at [Formula: see text] in the ferromagnetic (FM) ordering has been investigated. The study is accomplished using the full-potential (FP) linearized augmented plane wave plus local orbital (LAPW[Formula: see text]lo) self-consistent scheme of calculations. To incorporate the exchange correlation component in the total energy calculations of the crystal, Perdew–Burke and Ernzerhof (PBE) parameterization for the generalized gradient approximation (GGA) and GGA[Formula: see text]U are employed. Basically, for both alloys, to address their structural properties, we calculated their equilibrium lattice constants, bulk moduli as well as pressure derivatives. In general, from the analysis of the obtained electronic band structure of these alloys, the half-metallic nature of [Formula: see text] and nearly half-metallic nature of the [Formula: see text] alloy are demonstrated. The plotted density of states (DOS) curves project spin-exchange splitting energy [Formula: see text] and [Formula: see text] as generated by V-3d states. It has been clearly evident that the effective potential results for the spin-down case are more striking than for the spin-up case. In order to describe the magnetic behavior of these alloys, the exchange constants [Formula: see text] (valence band) and [Formula: see text] (conduction band) as well as the magnetic moment values are estimated. The calculated results of the magnetic moment show that the main source in the reduction of the local magnetic moment of V in the alloys in comparison with its free value is a [Formula: see text]–[Formula: see text] orbital hybridization and partial transfer to nonmagnetic sites of (Zn, S) and (Cd, S) in [Formula: see text] and [Formula: see text] alloys. In addition, a study concerning optical properties, such as the refractive index, reflectivity and absorption coefficients is performed to determine their potential for optical and optoelectronic devices.

scholarly journals First-principles study of structural, electronic and magnetic properties of Co-based quaternary Heusler compounds: CoFeCrAl, CoFeTiAs, CoFeCrGa and CoMnVAs

BIBECHANA ◽  
2017 ◽  
Vol 15 ◽  
pp. 50-59 ◽  
Author(s):  
Bikram Pandey ◽  
Ram Babu Ray ◽  
Gopi Chandra Kaphle
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Tight Binding ◽  
Lattice Parameter ◽  
Total Density ◽  
Heusler Compounds ◽  
Electronic Band ◽  
Half Metallic ◽  
Electronic And Magnetic Properties

We study the Structural, Electronic and Magnetic properties of Co-based LiMgPdSn-types of quaternary Heusler compounds (CoFeCrAl, CoFeTiAs, CoFeCrGa, and CoMnVAS) using Density Functional Theory (DFT) implemented on Tight Binding Linear Muffin-Tin Orbital within Atomic Sphere Approximation(TB-LMTO-ASA) Code. The optimized value of lattice parameter for CoFeCrAl, CoFeTiAs, CoFeCrGa and CoMnVAs are found to be 5.61A˚, 5.76 A˚, 5.61A˚ and 5.71A˚ respectively. From the calculation of electronic band structure and spin polarized total density of states (DOS), we found that CoFeCrAl and CoFeCrGa are spin-gapless semiconductor with half-metallic gap of 0.82eV and 0.25eV respectively. CoFeTiAs half-metals (Nearly spin-gapless semiconductor) with half-metallic gap 0.38 eV and CoMnVAs is found to be nearly gapless half-metal. Magnetic moment of these compounds almost obey the Slater-Pauling rules. All these compounds  expected to have high curie temperature which makes them significant for spintroincs/magnetoelectroincs applications.BIBECHANA 15 (2018) 50-59 

First-Principle Calculations of Half-Metallic Double Perovskite La2BB´O6(B,B´=3d transition metal)

2013 ◽  
Vol 14 (1) ◽  
pp. 174-185 ◽  
Author(s):  
Y. P. Liu ◽  
S. H. Chen ◽  
H. R. Fuh ◽  
Y. K. Wang
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Double Perovskite ◽  
Correlation Effect ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Half Metallic ◽  
Generalized Gradient Approximation ◽  
Full Structure ◽  
Magnetic States

AbstractIn this paper, we present calculations based on density functional theory using generalized gradient approximation (GGA) in double perovskite structure La2BB’O6 (B,B’ = 3d transition metal) out of combinational possibilities. Considering 4 types of magnetic states, namely, ferromagnetic (FM), ferrimagnetic (FiM), antiferromagnetics (AF), and nonmagnetic (NM) with full structure optimization, 13 possible surviving, stable FM/FiM-HM materials containing 6 FM-HM materials (La2ScNiO6, La2CrCoO6, La2CrNiO6, La2VScO6, La2VZnO6, and La2VNiO6) and 7 FiM-HM materials (La2VFeO6, La2ZnCoO6, La2TiCoO6, La2CrZnO6, La2CrMnO6, La2ScFeO6, and La2TiMnO6) are found. Considering the correlation effect (GGA+U), there are 6 possible half-metallic stable, surviving (HM) materials containing 3 FMHM materials (La2ScNiO6, La2CrCoO6, and La2CrNiO6) and 3 FiM-HM materials (La2VFeO6, La2ZnCoO6, and La2TiCoO6).

scholarly journals C-2p Spin-Polarizations along with Two Mechanisms in Extended Carbon Multilayers: Insight from First Principles

2020 ◽  
Vol 5 (3) ◽  
pp. 48
Author(s):  
Samir F. Matar
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Magnetic Charge ◽  
The Other ◽  
Single Atom ◽  
Total Density ◽  
Metallic Behavior ◽  
Functional Theory ◽  
Half Metallic ◽  
Total Density Of States

From density functional theory investigations helped with crystal chemistry rationale, single-atom C, embedded in layered hexagonal CC’n (n = 6, 12 and 18) networks, is stable in a magnetic state with M(C) = 2 μB. The examined compositions, all inscribed within the P6/mmm space group are characterized as increasingly cohesive with n, figuring mono-, bi- and tri-layered honeycomb-like C’6 networks respectively. The spin projected total density of states shows a closely half-metallic behavior with a gap at minority spins (↓) and metallic majority spins (↑). Such results together with the large C-C intersite separation and the integer 2 μB magnetization, let us propose an intra-band mechanism of magnetic moment onset on carbon 2p states. Support is provided from complementary calculations assuming a C2C’12 structure with planar 2C with d(C-C) = 2.46 Å resulting into a lowering of the magnetization down to the 0.985 μB/C atom and a ferromagnetic order arising from interband spin polarization on C where one nonbonding spin polarizes whereas the other is involved with the bonding with the other carbon. Illustration of proofs is provided with the magnetic charge density projected onto the different atoms, showing its prevalence around C, contrary to the C’n (C’6 layers), as well as electron localization function ELF.

Ab initio calculation on the Optical Properties of AA- Stacked two dimensional Graphene, Silicene, Germanene, and Stanene

2018 ◽  
Vol 1 (1) ◽  
pp. 46-50
Author(s):  
Rita John ◽  
Benita Merlin
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Complex Refractive Index ◽  
Single Layer ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Wide Range ◽  
Optical Region

In this study, we have analyzed the electronic band structure and optical properties of AA-stacked bilayer graphene and its 2D analogues and compared the results with single layers. The calculations have been done using Density Functional Theory with Generalized Gradient Approximation as exchange correlation potential as in CASTEP. The study on electronic band structure shows the splitting of valence and conduction bands. A band gap of 0.342eV in graphene and an infinitesimally small gap in other 2D materials are generated. Similar to a single layer, AA-stacked bilayer materials also exhibit excellent optical properties throughout the optical region from infrared to ultraviolet. Optical properties are studied along both parallel (||) and perpendicular ( ) polarization directions. The complex dielectric function (ε) and the complex refractive index (N) are calculated. The calculated values of ε and N enable us to analyze optical absorption, reflectivity, conductivity, and the electron loss function. Inferences from the study of optical properties are presented. In general the optical properties are found to be enhanced compared to its corresponding single layer. The further study brings out greater inferences towards their direct application in the optical industry through a wide range of the optical spectrum.

Dissociation of dinitrogen on iron clusters: A detailed study of the Fe16 + N2 case.

2020 ◽  
Author(s):  
Bole Chen ◽  
Gennady L. Gutsev ◽  
Weiguo Sun ◽  
Xiao-Yu Kuang ◽  
Cheng Lu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Basis Set ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Iron Clusters ◽  
Generalized Gradient Approximation

The coalescence of two Fe8N as well as the structure of the Fe16N2 cluster were studied using density functional theory with the generalized gradient approximation and a basis set of...

scholarly journals GGA/PBE study of the spin isomers of Fe34,40, Co23,34, and Co12Cu Clusters with Selected Geometries

2017 ◽  
Vol 56 (3) ◽  
Author(s):  
Faustino Aguilera-Granja ◽  
Andrés Vega ◽  
Luis Carlos Balbás
Keyword(s):  
Ground State ◽  
Density Functional ◽  
Energy Difference ◽  
Many Body ◽  
Generalized Gradient ◽  
Structural Isomers ◽  
Functional Theory ◽  
Ferromagnetic Ground State ◽  
Spin Isomers ◽  
Pseudo Potential

In a recent beam deflecting experiment was found that high and low spin states of pure Fe<sub>n</sub> and Co<sub>n</sub> clusters with <em>n</em> ≤ 300 atoms coexist at cryogenic temperatures. In this work we have studied the high spin (HS) and low spin (LS) states of several structural isomers of Co<sub>23</sub>, Co<sub>34</sub>, Fe<sub>34</sub>, and Fe<sub>40</sub> using the generalized gradient approximation (GGA) to density functional theory as implemented in the first-principles pseudo-potential code SIESTA. The calculated energy difference between these HS and LS isomers is not consistent with the observed coexistence, which can be due to an insufficient account of many body correlation effects in the GGA description, or to unknown isomer structures of these clusters. We have calculated within the same tools the magnetic isomers of Co<sub>12</sub>Cu cluster aimed to re-visit a former DFT prediction of an anti-ferromagnetic ground state. We find, however, a ferromagnetic ground state as expected on physical grounds. Our results exemplify the difficulties of the current DFT approaches to describe the magnetic properties of transition metal systems.

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