scholarly journals Half-Metallic Ferromagnetism in Double Perovskite Ca2CoMoO6 Compound: DFT+U Calculations

SPIN ◽  
2017 ◽  
Vol 07 (04) ◽  
pp. 1750009 ◽  
Author(s):  
A. Djefal ◽  
S. Amari ◽  
K. O. Obodo ◽  
L. Beldi ◽  
H. Bendaoud ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Ground State ◽  
Magnetic Semiconductor ◽  
Double Perovskite ◽  
Systematic Investigation ◽  
Full Potential ◽  
Generalized Gradient ◽  
Half Metallic ◽  
Ferromagnetic Ground State ◽  
The Stability

A systematic investigation on magnetism and spin-resolved electronic properties in double perovskite Ca2CoMoO6 compound was performed by using the full-potential augmented plane wave plus local orbitals (APW[Formula: see text]) method within the generalized gradient approximation (GGA-PBE) and GGA-PBE[Formula: see text] scheme. The stability of monoclinic phase ([Formula: see text] #14) relative to the tetragonal ([Formula: see text]#87) and cubic ([Formula: see text] #225) phase is evaluated. We investigate the effect of Hubbard parameter [Formula: see text]on the ground-state structural and electronic properties of Ca2CoMoO6 compound. We found that the ferromagnetic ground state is the most stable magnetic configuration. The calculated spin-polarized band structures and densities of states indicate that the Ca2CoMoO6 compound is half-metallic (HM) and half-semiconductor (HSC) ferromagnetic (FM) semiconductor with a total magnetic moment of 6.0 using GGA-PBE and GGA-PBE[Formula: see text], respectively. The Hubbard [Formula: see text] parameter provides better description of the electronic structure. Using the Vampire code, an estimation of exchange couplings and magnetic Curie temperature is calculated. Further, our results regarding the magnetic properties of this compound reveal their ferromagnetic nature. The GGA-PBE[Formula: see text] approach provides better band gap results as compared to GGA-PBE approximation. These results imply that Ca2CoMoO6 could be a promising magnetic semiconductor for application in spintronic devices.

scholarly journals 5f Delocalization of Bulk FCC Americium and the (111) Surface: A FP-LAPW Electronic Structure Study

2005 ◽  
Vol 893 ◽  
Author(s):  
Da Gao ◽  
Asok K Ray
Keyword(s):  
Electronic Properties ◽  
Local Density ◽  
Structure Study ◽  
Orbit Coupling ◽  
Full Potential ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Generalized Gradient ◽  
Quantum Size ◽  
Ferromagnetic Ground State

AbstractThe electronic properties of bulk fcc americium and the (111) surface have been investigated with the full-potential linearized augmented plane wave (FP-LAPW) method as implemented in the WIEN2K suite of programs The study is carried out for the anti-ferromagnetic ground state of Am at different levels of theory: (1) scalar-relativity vs. full-relativity; (2) local-density approximation (LDA) vs. generalized-gradient approximation (GGA). Our results indicate that spin orbit coupling plays an important role in determining the electronic properties of both bulk fcc americium and the (111) surface. In general, LDA is found to give a higher total energy compared to GGA results. The spin orbit coupling shows a similar effect on the surface calculations regardless of the model, GGA versus LDA. The 5f localized-delocalized transition of americium is employed to explain our results. In addition, the quantum size effects in the surface energies and the work functions of fcc (111) americium ultra thin films (UTF) are also examined.

scholarly journals Half-metallic Ferromagnetism in Non-magnetic Double Perovskite Oxides Sr2MSbO6 (M=Al, Ga) Doped with C and N.

2021 ◽  
Author(s):  
AMRANI Bouhalouane ◽  
Djilali BENDJEBBOUR ◽  
Tayeb SEDDIK ◽  
Mohamed Walid MOHAMED ◽  
driss khdoja
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Double Perovskite ◽  
Perovskite Oxides ◽  
Full Potential ◽  
Double Perovskites ◽  
Generalized Gradient ◽  
Half Metallic ◽  
Impurity Bands ◽  
C And N

Abstract Double perovskite oxides have gained tremendous attention in material science and device technology due to their facile synthesis and exceptional physical properties. In this paper, we elucidate the origin of magnetization in non magnetic double perovskite oxides Sr2MSbO6 (M=Al, Ga) induced by non-magnetic 2p-impurities (C and N) substituted. The calculations were done within the full potential linearized augmented plane wave method (FP-LAPW) in the framework of the density functional theory (DFT). The exchange-correlation potential is evaluated using the generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof (PBE) and the modified Becke and Johnson (mBJ-GGA). Regarding structural properties of undoped double perovskites Sr2MSbO6 (M=Al, Ga), we found that the lattice constants and oxygen positions are in rational accord with the experimental results. Furthermore, both of the examined compounds are brittle in nature with isotropic character. For Sr2AlSbO6 we have got the values of energy gap equal to 1.9 eV and 3.7 eV within the GGA and the mBJ-GGA, respectively. However for Sr2GaSbO6 the values of energy gap obtained in GGA and mBJ-GGA are equal to 0.8 eV and 2.9 eV, respectively. Finally, spin-polarized calculations reveal that the doping C and N can lead to drastic changes in the magneto-electronic properties of the semiconducting Sr2MSbO6 matrix with the integer magnetic moment of 6.00 µB and exhibit half-metallic properties. The origin of ferromagnetism can be attributed to the spin–split impurity bands inside the energy gap of the semiconducting Sr2MSbO6 matrix. These results may help experimentalists in synthesizing new double perovskites for spintronic applications.

Modified Becke-Johnson Approach for Governing Half Metallic Ferromagnetism in Cr-Doped GaP DMS Compound

2012 ◽  
Vol 585 ◽  
pp. 265-269
Author(s):  
Hardev S. Saini ◽  
Mukhtiyar Singh ◽  
Manish K. Kashyap
Keyword(s):  
Spin Exchange ◽  
Local Density ◽  
Magnetic Semiconductor ◽  
Full Potential ◽  
Generalized Gradient ◽  
Half Metallic ◽  
Augmented Plane Wave ◽  
Linearized Augmented Plane Wave ◽  
Metallic Ferromagnetism ◽  
Half Metallic Ferromagnetism

The electronic and magnetic properties of Ga1-xCrxP Dilute Magnetic Semiconductor (DMS) compound at doping concentration, x = 0.125 has been calculated using full potential linearized augmented plane wave (FPLAPW) method. The exchange and correlation (XC) effects are taken into account by a semi local, orbital independent modified Becke-Johnson (mBJ) potential as coupled with Local Density Approximation (LDA). Our calculation shows that Cr induces the ferromagnetism in this compound and there is large half metallic (HM) gap appearing in the minority spin channel. We observed that mBJLDA potential enhances the HM gap by ~ 0.25 eV as compared to from its value in Generalized Gradient Approximation (GGA). The improved HM gap can be understood in terms of the mBJLDA-enhanced spin exchange splitting.

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.

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.

Electronic properties of austenite and martensite Fe-9%Mn alloys

Open Physics ◽  
2008 ◽  
Vol 6 (4) ◽  
Author(s):  
Ercan Uçgun ◽  
Hamza Ocak
Keyword(s):  
Total Energy ◽  
Electronic Properties ◽  
Lattice Relaxation ◽  
The Self ◽  
Full Potential ◽  
Generalized Gradient ◽  
Plane Wave Method ◽  
Lattice Constants ◽  
Generalized Gradient Approximation ◽  
Self Consistent

AbstractWe calculate the electronic properties of austenite and martensite Fe-9%Mn alloys using the self consistent full-potential linearized-plane-wave method under the generalized gradient approximation full lattice relaxation. By minimizing total-energy, the lattice constants in their ground states were determined. We discuss the total energy dependence of the volume, and density of states (DOS).

Half-metallic ferromagnetism in V-doped ZnTe semiconductor at reduced dopant concentration

2014 ◽  
Vol 28 (13) ◽  
pp. 1450104 ◽  
Author(s):  
M. Sajjad ◽  
H. X. Zhang ◽  
N. A. Noor ◽  
S. M. Alay-e-Abbas ◽  
M. Abid ◽  
...  
Keyword(s):  
Density Functional ◽  
Spin Exchange ◽  
Density Functional Theory Calculations ◽  
Orbital Method ◽  
Ferromagnetic Behavior ◽  
Full Potential ◽  
Local Spin Density Approximation ◽  
Generalized Gradient ◽  
Half Metallic ◽  
Bonding Properties

In this study, we examine the structural, electronic, magnetic and bonding properties of zincblende phase Zn 1-x V x Te (x = 0.0625, 0.125, 0.25) compounds to present them as suitable candidates for spintronic applications. Density functional theory calculations have been used by implementing the accurate full-potential linear-augmented-planewave plus local-orbital method. Structural properties have been computed using Wu–Cohen generalized gradient approximation, whereas the modified Becke and Johnson local (spin) density approximation (mBJLDA) function has been employed for the evaluating ground state electronic properties and ferromagnetic behavior. The half-metallic (HM) ferromagnetism in Zn 1-x V x Te is analyzed in terms of V -3d states and it is shown that mBJLDA predicts wide HM gaps which promise the possibility of achieving V -doped ZnTe with high Curie temperature. The spin exchange splittings Δx(d) and Δx(pd) have been estimated and the contribution of conduction band (CB) and valence band (VB) in exchange splitting is calculated in terms of the exchange constants N0α and N0β. Furthermore, spin-polarized charge density calculation is presented for elucidating the bonding nature, while pressure dependence of total magnetic moment for three concentrations of V -doped ZnTe is also discussed.

scholarly journals Half-Metallic Property Induced by Double Exchange Interaction in the Double Perovskite Bi2BB′O6 (B, B′ = 3d Transitional Metal) via First-Principles Calculations

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1844 ◽  
Author(s):  
Hong-Zong Lin ◽  
Chia-Yang Hu ◽  
Po-Han Lee ◽  
Albert Zhong-Ze Yan ◽  
Wen-Fang Wu ◽  
...  
Keyword(s):  
Exchange Interaction ◽  
Density Functional ◽  
Double Exchange ◽  
Double Perovskite ◽  
Transition Metal Ions ◽  
Spin Interaction ◽  
Metallic Materials ◽  
Generalized Gradient ◽  
Double Exchange Interaction ◽  
Half Metallic

In this paper, we identify three possible candidate series of half-metals (HM) from Bi-based double perovskites Bi2BB′O6 (BB′ = transition metal ions) through calculations utilizing the density functional theory (DFT) and full-structural optimization, in which the generalized gradient approximation (GGA) and the strong correlation effect (GGA + U) are considered. After observing the candidate materials under four types of magnetic states, i.e., ferromagnetic (FM), ferrimagnetic (FiM), antiferromagnetic (AF), and nonmagnetic (NM), we found eight promising candidates for half-metallic materials. Under the GGA scheme, there are three ferromagnetic-half-metal (FM-HM) materials, Bi2CrCoO6, Bi2CrNiO6 and Bi2FeNiO6, and three FiM-HM materials, Bi2FeZnO6, Bi2CrZnO6 and Bi2CoZnO6. With implementation of the Coulomb interaction correction (GGA + U), we find two stable half-metallic materials: Bi2CrNiO6 and Bi2CrZnO6. We determine that the stability of some of these materials are tied to the double exchange interaction, an indirect interaction within the higher powers of localized spin interaction among transition metals via oxygen ions. Found in half-metallic materials, and especially those in the ferromagnetic (FM) state, the double exchange interaction is recognized in the FM-HM materials Bi2CrCoO6 and Bi2FeNiO6.

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.

First-principles study of structural, electronic and optical properties of the KCaX3 (X = F and Cl) compounds

2014 ◽  
Vol 28 (21) ◽  
pp. 1450139 ◽  
Author(s):  
Ahmad A. Mousa
Keyword(s):  
Hydrostatic Pressure ◽  
Band Gap ◽  
Electronic Properties ◽  
Energy Band ◽  
Theoretical Data ◽  
Full Potential ◽  
Energy Band Gap ◽  
Generalized Gradient ◽  
Electron Charge Density ◽  
Bonding Properties

Structural and electronic properties of perovskite KCaX 3  (X = F and Cl ) compounds are investigated using the full potential linearized augmented plane wave (FP-LAPW) method as implemented in the Wien2k code. The exchange-correlation potential is treated by the generalized gradient approximation within the scheme of Perdew, Burke and Ernzerhof (GGA-PBE). Based on these calculations, it has been concluded that KCaX 3 compounds have indirect energy band-gap (Γ-R). Moreover, the theoretical investigation which has been carried out on the highly hydrostatic pressure dependence of the KCaX 3 electronic properties revealed a linear relationship between both the hydrostatic pressure and the energy band-gap. In addition, the electronic and bonding properties of the band structure, density of states (DOS) and electron charge density have been calculated and presented. Besides that, the dielectric function, refractive index and extinction coefficient are calculated. The origin of some of the peaks in the optical spectra is discussed in terms of the calculated electronic structure. Finally, the calculated structural properties are found to agree well with the available experimental and theoretical data.

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