First-principles prediction of insulating antiferromagnet in ordered double-perovskite Ca2MnMoO6 compound

2017 ◽  
Vol 06 (04) ◽  
pp. 1750027 ◽  
Author(s):  
A. Djefal ◽  
S. Amari ◽  
K. O. Obodo ◽  
L. Beldi ◽  
H. Bendaoud ◽  
...  
Keyword(s):  
Magnetic Moment ◽  
Density Functional ◽  
Energy Gap ◽  
Double Perovskite ◽  
Ferromagnetic Phase ◽  
Full Potential ◽  
Generalized Gradient ◽  
Spin Configuration ◽  
Metallic Character ◽  
Conduction Bands

Using first-principle calculations within the framework of density functional theory (DFT), the full-potential linearized augmented plane-wave (FP-LAPW) method have been performed to investigate structural, electronic and magnetic properties of the Ca2MnMoO6 double perovskite. Different spin configurations (ferromagnetic (FM), ferrimagnetic (FiM), and anti-ferromagnetic AFM1, and AFM2) within both generalized gradient approximation (GGA) and [Formula: see text] (Hubbard Coulomb onsite correction) were considered. The value of the Hubbard−Coulomb [Formula: see text] parameter was varied in the range of [Formula: see text][Formula: see text]eV. The ground state is found to be AFM and insulating with the AFM1 state which is the most favorable. In the AFM1 spin configuration, Ca2MnMoO6 compound has a semiconductor nature, with the fully spin-polarized valence and conduction bands in the same spin channel. Within the [Formula: see text] approximation, the FM phase has a half-metallic character with a net magnetic moment of [Formula: see text] while in the anti-ferromagnetic phase it has an insulating character with zero net magnetic moment which was found at [Formula: see text][Formula: see text]eV. We found that in the AFM phase within the GGA approximation, a metallic character is obtained for Ca2MnMoO6 and also for [Formula: see text][Formula: see text]eV. In particular, for Hubbard [Formula: see text] of 3.6[Formula: see text]eV, a small energy gap of 0.20[Formula: see text]eV is observed. The main features shown by the density of states curves motivate further experimental exploration in the double perovskite Ca2MnMoO6 for spintronic applications.

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.

scholarly journals Prediction of electronic and optical properties for Zn1-xCdxSeyTe1-y quaternary alloys: First-principles study

2021 ◽  
Vol 67 (4 Jul-Aug) ◽  
pp. 041001
Author(s):  
K. Benchikh ◽  
M. Benchehima ◽  
H. A. Bid ◽  
A. Chabane Chaouche
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Energy Gap ◽  
Local Density ◽  
Quaternary Alloy ◽  
Full Potential ◽  
Generalized Gradient ◽  
Quaternary Alloys ◽  
Electronic And Optical Properties ◽  
The Density Functional Theory

In the present work, the density functional theory (DFT) was performed for the investigation of the structural, electronic and optical properties of the Zn1-xCdxSeyTe1-y quaternary alloys using the full potential linearized augmented plane wave (FP-LAPW) method. For the calculations of the structural properties we have used the Perdew-Burke-Ernzerhof generalized gradient approximation (GGA-PBEsol). On other hand, the electronic properties have been computed within the local density approximation (LDA) in adding to the Tran-Blaha modified Becker-Johnson (TB-mBJ) approach. Our results indicate that the lattice constant, as well as the bulk modulus and the energy gap for the Zn1-xCdxSeyTe1-y quaternary show almost linear variations on the concentration x (0.125≤x≤0.875). In addition, the simulated band structures for theZn1-xCdxSeyTe1-y quaternary exhibits a direct-gap for all concentrations. Moreover, low bowing parameters are observed. Also, some interesting optical properties such as dielectric constant, refractive index, extinction coefficient, absorption coefficient and reflectivity have been calculated by using the TB-mBJ method.  The results of our computations shows that theZn1-xCdxSeyTe1-y quaternary alloy is a promissing candidate for optoelectronic applications. It is noteworthy that the present work is the first theoretical study of the quaternary of interest using the FP-LAPW calculations.

scholarly journals Heavy Thallium Based Fluoroperovskite TlAF3 (A = Ge, Sn and Pb) Compounds: A Computational Investigation

2021 ◽  
Author(s):  
Shams U Zaman ◽  
Nasir Mehmood ◽  
Sajid Khan ◽  
Rashid Ahmad ◽  
Nadia Sultan ◽  
...  
Keyword(s):  
Density Functional ◽  
Effective Atomic Number ◽  
Full Potential ◽  
Generalized Gradient ◽  
Lattice Constants ◽  
Conduction Bands ◽  
The Density Functional Theory ◽  
Theoretical Investigations ◽  
First Time ◽  
Linearized Augmented Plane Wave

Abstract Combination of heavy elements in forming a stable system leads to enhancement in effective atomic number making it desirable in many applications such as detection and shielding of radiation. We present our theoretical investigations on new Thallium based heavy fluoroperovskites TlAF3 (A = Ge, Sn and Pb). The study is carried out to explore the structural, elastic, electronic, and optical properties through the Density Functional Theory (DFT) using the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method implemented in WIEN2k. Generalized Gradient Approximation with consideration of electronic correlation effects (GGA+U) was employed for calculations. The lattice constants deduced from the optimization curves were found to be in the range of 4.00 Å to 4.85 Å. Elastic properties were obtained from the calculated elastic constants. From band structure calculations, it is evident that the bandgaps range from 0.84 to 1.89 eV. All the studied compounds exhibit indirect bandgap nature. Fluorine atom contributes significant number of electronic states in valence and conduction bands of all studied compounds. The optical response in terms of refractive index, extinction coefficient, optical conductivity, reflectivity, and absorption coefficients are calculated and discussed in the energy range of (0-20) eV. The properties of compounds in this study are being reported for the first time.

First-Principles Study of Structural, Electronic, Optical and Elastic Properties of Cadmium Based Fluoro-Perovskite MCdF3 (M= Rb, Tl)

2019 ◽  
Vol 297 ◽  
pp. 173-186 ◽  
Author(s):  
Abderrahmane Cheriet ◽  
Brahim Lagoun ◽  
Mohamed Halit ◽  
Mourad Zaabat ◽  
Chadli Abdelhakim ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Local Density ◽  
Poisson Ratio ◽  
Exchange Potential ◽  
Full Potential ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Conduction Bands

This paper presents a theoretical study using the full potential linearized augmented plane wave approach (FP-LAPW) based on the density functional theory (DFT) to predict the structural and electronic properties of RbCdF3 and TlCdF3 compounds. The exchange-correlation potential is treated by the local density approximation (LDA), generalized gradient approximation (GGA) and modified Beck-Johnson exchange potential (mBJ). The calculated structural properties such as the equilibrium lattice parameter, the bulk modulus and its pressure derivative are in good agreement with the available data. The obtained results for the band structure and the density of states (DOS) show that the RbCdF3 (TlCdF3) compound have an indirect band gap of 6.77 and 3.07 eV (5.70 and 3.66 eV) with TB-mBJ and WC method respectively. From the electronic transition from valence conduction bands to conduction bands the optical properties were calculated. The elastic constants were calculated using the energy deformation relationship, from these constants the other mechanical properties such as bulk modulus, shear modulus, Young modulus and Poisson ratio were calculate and comment. Lastly, the elastic anisotropy was discussed.

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 Density functional studies of magneto-optic properties of Sr2GdReO6

2018 ◽  
Vol 4 (1) ◽  
pp. 13-19 ◽  
Author(s):  
Saadi Berri ◽  
Sabah Chami ◽  
Mourad Attallah ◽  
Mouloud Oumertem ◽  
Djamel Maouche
Keyword(s):  
Density Functional ◽  
Interaction Mechanism ◽  
Double Perovskite ◽  
Full Potential ◽  
Ambient Conditions ◽  
Generalized Gradient ◽  
Half Metallicity ◽  
Double Exchange Interaction ◽  
Electronic Band ◽  
Magneto Optic

The electronic structure and magneto-optic properties of the Sr2GdReO6 double perovskite were investigated using the full-potential linearized augmented plane wave (FPLAPW) method. Exchange correlation effects are treated using the generalized gradient approximations GGA, GGA + U and GGA + U + SOC approachs. At ambient conditions, these calculation predict a half-metallic character for Sr2GdReO6 material. The electronic band structures and density of states demonstrate that Sr2GdReO6 is HM with a magnetic moment of 9 µB/fu and HM flip gap of 1.82 eV. The half metallicity is attributed by the double-exchange interaction mechanism via the Gd(4f)–O(2p)–Re(t2g) π-bounding. These new double perovskite may become ideal candidate material for future spintronic applications. The analysis charge densities show that bonding character as a mixture of covalent and ionic nature. The optical properties are analyzed and the origin of some peaks in the spectra is described. Besides, the dielectric function ε(ω), refractive index n (ω) and extinction coefficient K (ω) for radiation up to 14 eV have also been reported.

Calculation of Structural, Electronic and Optical Properties of Double Perovskite Ca2CrNbO6

SPIN ◽  
2021 ◽  
pp. 2150012
Author(s):  
W. Benosmane ◽  
S. Benatmane ◽  
R. Bentata ◽  
W. Benstaali
Keyword(s):  
Density Functional ◽  
Double Perovskite ◽  
Full Potential ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Generalized Gradient Approximation ◽  
Spin Polarized ◽  
Optical Dielectric ◽  
Linearized Augmented Plane Wave

The structural electronic and magnetic properties of the double perovskite Ca2CrNbO6 in the cubic structure are investigated using the empirical full-potential linearized augmented plane wave (FP-LAPW) method within the framework of the spin-polarized density functional theory (DFT). These properties are calculated using the Generalized Gradient Approximation (GGA), [Formula: see text] and modified Becke–Johnson mBJ-GGA. In addition, the real and imaginary parts of the optical dielectric function and the reflectivity, and the refractive spectra are computed and the main features shown by their spectra are ascertained on the base of the investigation of density of states.

STRUCTURAL, MAGNETIC AND ELECTRONIC PROPERTIES OF THE Sr2CoNbO6 COMPLEX PEROVSKITE

2013 ◽  
Vol 27 (28) ◽  
pp. 1350171 ◽  
Author(s):  
J. M. RENDÓN RAMÍREZ ◽  
O. A. ALMANZA M. ◽  
R. CARDONA ◽  
D. A. LANDÍNEZ TÉLLEZ ◽  
J. ROA-ROJAS
Keyword(s):  
Electronic Properties ◽  
Structure Prediction ◽  
Density Functional ◽  
Energy Gap ◽  
Magnetic Ordering ◽  
Double Perovskite ◽  
Rietveld Analysis ◽  
Lattice Parameters ◽  
Blocking Temperature ◽  
Generalized Gradient

We report a study of crystallographic parameters of the Sr 2 CoNbO 6 double perovskite obtained from Rietveld analysis of X-ray diffraction data and electronic properties predictions using the density functional theory (DFT). The Sr 2 CoNbO 6 material was prepared by the citrate precursor method. Diffraction analysis reveal that this material crystallizes in a structure which is tetragonal with lattice parameters a = 5.5960(3) Å and c = 7.9881(1) Å (space group I4/m). The density of states of Sr 2 CoNbO 6 tetragonal distorted structure was calculated using DFT within the generalized gradient approximation. Results predict the semiconductor characteristics of this material which is majority due to the 3d- Co orbital with a energy gap of 0.2 eV. Structural lattice parameters obtained from the Rietveld refinement present a matching of 97% with that obtained from the Structure Prediction Diagnostic Software and 98% with the theoretical DFT results. Measurements of magnetization as a function of temperature evidence the occurrence of a magnetic ordering transition at T = 220 K and a marked irreversibility with a blocking temperature of 250 K for applied fields up to 100 Oe, which disappears for higher fields. Electronic paramagnetic resonance experiments evidence that the valence Co 3+ is the most possible in the synthesized material.

Electronic Structure of Complex Bismuth Chalcogenides and Other Narrow-Gap Thermoelectric Materials

1998 ◽  
Vol 545 ◽  
Author(s):  
S. D. Mahanti ◽  
P. Larson ◽  
Duck-Young Chung ◽  
S. Sportouch ◽  
M. G. Kanatzidis
Keyword(s):  
Electronic Structure ◽  
Valence Band ◽  
Thermoelectric Materials ◽  
Density Functional ◽  
Energy Gap ◽  
Full Potential ◽  
Narrow Gap ◽  
Gap Formation ◽  
Generalized Gradient ◽  
Physical Reason

AbstractThere is considerable current effort to discover new thermoelectric materials with a high figure of merit Z. Some of these new materials are narrow-gap semiconductors with rather complex crystal structures. In this paper we discuss the results of electronic structure calculations in two classes of such systems. The first class consists of BaBiTe3, a structural and chemical derivative of the well-studied Bi2Te3. Similarities and differences in the band structures of these two systems are discussed. The second class consists of half-Heusler or “stuffed”-NaCl compounds MNiX, where M is Y, La, Lu, Yb, and X is a pnictogen; As, Sb, Bi. To understand the physical reason behind the energy gap formation, we compare the electronic structure of YNiSb with that of an isoelectronic system ZrNiSn, another isostructural compound of thermoelectric interest. These calculations were carried out within density functional theory (in generalized gradient approximation) using self-consistent full-potential LAPW method. Energy gaps and effective masses associated with the conduction band minimum and valence band maximum have been calculated and these quantities have been used to estimate transport properties. Large room temperature thermopower values in Bi2Te3 and BaBiTe3 can be understood in terms of multiple conduction and valence band extrema whereas similar large values in ZrNiSn and other half-Heusler compounds can be ascribed to large electron and hole effective mass.

First-principles calculations for optical investigations of PbX (X = S, Te) compounds under quantum dots diameter effect

2015 ◽  
Vol 93 (12) ◽  
pp. 1490-1494 ◽  
Author(s):  
Y. Al-Douri ◽  
H. Khachai ◽  
R. Khenata ◽  
A. Bouhemadou
Keyword(s):  
Quantum Dot ◽  
Density Functional ◽  
Energy Gap ◽  
Theoretical Data ◽  
Full Potential ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Optical Dielectric Constant ◽  
Optical Dielectric ◽  
Linearized Augmented Plane Wave

The full potential-linearized augmented plane wave (FP-LAPW) method is implemented in WIEN2K code to calculate the indirect energy gap (Γ–X) using density functional theory. The Engel–Vosko generalized gradient approximation (EVGGA) and modified Becke–Johnson (mBJ) formalisms are used to optimize the corresponding potential for energetic transition and optical properties calculations of PbS and PbTe compounds as a function of quantum dot diameter and are used to test the validity of our model of quantum dot potential. The refractive index and optical dielectric constant are investigated to explore best applications for solar cells. The calculated results are in agreement with other experimental and theoretical data.

Sign in / Sign up

Export Citation Format

Share Document