FIRST-PRINCIPLES STUDY OF THE EFFECTS OF THE OXYGEN VACANCY ON ELECTRONIC STRUCTURE AND FERROMAGNETISM OF Sn2 Co2O8-δ

2010 ◽  
Vol 24 (14) ◽  
pp. 2229-2235
Author(s):  
KAIHUA HE ◽  
GUANG ZHENG ◽  
HANLIE HONG ◽  
MIAO WAN ◽  
GUANGFU JI
Keyword(s):  
Electronic Structure ◽  
Oxygen Vacancy ◽  
Magnetic Moment ◽  
First Principles ◽  
Magnetic Moments ◽  
Generalized Gradient ◽  
Spin Magnetic Moment ◽  
Metallic Behavior ◽  
Half Metallic ◽  
Single Oxygen

The electronic structure and ferromagnetism of Sn 2 Co 2 O 8 and Sn 2 Co 2 O 7 have been investigated based on the first-principles plane-wave pseudopotential method within the generalized gradient approximation. The calculated results reveal that the oxygen vacancy plays an important role in the electronic structure and ferromagnetism. The Sn 2 Co 2 O 8 shows half-metallic behavior, but by introducing single oxygen vacancy, the half-metallic transits to metallic behavior. At the same time, the spin magnetic moment of every Co atom and the total magnetic moment change greatly. For Sn 2 Co 2 O 8 and Sn 2 Co 2 O 7, the total spin magnetic moments are 1.99 and 3.49 uB, respectively.

First-principles investigations of the half-metallic ferromagnetic LaCoTiIn equiatomic quaternary Heusler alloy for spintronics

2021 ◽  
Author(s):  
V. Aravindan ◽  
A. K. Rajarajan ◽  
V. Vijayanarayanan ◽  
M. Mahendran
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Magnetic Moment ◽  
First Principles ◽  
Heusler Alloy ◽  
Great Influence ◽  
Total Spin ◽  
Spin Magnetic Moment ◽  
Metallic Behavior ◽  
Half Metallic

We have evaluated the structural and mechanical stability, electronic structure, total spin magnetic moment, and Curie temperature of LaCoTiIn Equiatomic Quaternary Heusler Alloy (EQHA) using first-principles studies. The Generalized Gradient Approximation (GGA) and GGA+U schemes have been used as exchange-correlation functional for the above calculations. From the ground state calculation, LaCoTiIn EQHA with a Type-III structure in the ferromagnetic (FM) state is found to be stable. The electronic structure of LaCoTiIn EQHA depicts half-metallic behavior which has metallic overlap in the spin up ([Formula: see text] channel and a semiconductor band gap in the other channel. The spin–orbit coupling of LaCoTiIn has a great influence on the band gap of the material. The computed band gap values for the spin down ([Formula: see text] channel are 0.480 eV and 0.606 eV by using the GGA and GGA+U schemes. The total spin magnetic moment is 1 [Formula: see text], according to the Slater–Pauling rule, [Formula: see text] = ([Formula: see text] - 18) [Formula: see text]. These results obtained can be used as a valuable reference for future research, or they will be used to further motivate the experimental synthesis of the corresponding alloy.

FIRST PRINCIPLES STUDY OF THE ELECTRONIC STRUCTURE AND FERROMAGNETISM OF THE V-DOPED BN(5, 5) NANOTUBE

2008 ◽  
Vol 22 (18) ◽  
pp. 1749-1756 ◽  
Author(s):  
K. H. HE ◽  
G. ZHENG ◽  
G. CHEN ◽  
M. WAN ◽  
G. F. JI
Keyword(s):  
Electronic Structure ◽  
Magnetic Moment ◽  
First Principles ◽  
Generalized Gradient ◽  
Half Metallic ◽  
Ferromagnetic Properties ◽  
Generalized Gradient Approximation ◽  
First Principles Study ◽  
Spin Polarized

The structural, electronic and ferromagnetic properties of the V-doped BN(5, 5) are investigated by using first-principles spin-polarized calculations within generalized gradient approximation. The optimized structure shows that the V atom moves outwards and the hexagonal rings with the V atom experience significant distortion. The electronic structure indicates that the V-doped BN(5, 5) nanotube is half-metallic. The majority ferromagnetic moment comes from the V atom and slight magnetic moment is provided by the B atoms which are near to the V atom, while a little negative magnetic moment is contributed by the N atoms.

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.

FIRST PRINCIPLES STUDY OF ELECTRONIC STRUCTURE AND MAGNETIC PROPERTIES OF HALF-METALLIC FULL-HEUSLER ALLOYS Co2MnSi and Co2FeSi

2010 ◽  
Vol 24 (08) ◽  
pp. 967-978 ◽  
Author(s):  
JINGSHAN QI ◽  
HAILIN YU ◽  
XUEFAN JIANG ◽  
DANING SHI
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
Density Functional ◽  
Energy Gap ◽  
Magnetic Moments ◽  
Heusler Alloys ◽  
Lattice Parameters ◽  
Generalized Gradient ◽  
Half Metallicity ◽  
Half Metallic

We present a comprehensive investigation of the equilibrium structural, electronic and magnetic properties of C o2 MnSi and C o2 FeSi by density-functional theory (DFT) within the generalized gradient approximation (GGA) using the projected augmented wave (PAW) method. The on-site Coulomb interaction has also taken into account ( GGA +U) approach to unravel the correlation effects on the electronic structure. The change of the energy gap, "spin gap", Fermi energy level and magnetic moments with the lattice parameters is investigated. We found that the on-site correlation interaction in C o2 FeSi is stronger than in C o2 MnSi . So on-site electronic correlation is necessary for C o2 FeSi and the magnetic moments reproduce experimental results well by GGA +U. Further we also found that a moderate change of the lattice parameters does not change the half-metallic ferromagnet (HMF) behavior for both materials. Appearance of half-metallicity is consistent with the integral magnetic moments, which also agrees with the experiment measurements.

ELECTRONIC STRUCTURE AND MAGNETIC PROPERTIES OF Co2YZ(Y = Cr, Z = Al, Ga) TYPE HEUSLER COMPOUNDS: A FIRST PRINCIPLE STUDY

2012 ◽  
Vol 26 (08) ◽  
pp. 1250071 ◽  
Author(s):  
D. P. RAI ◽  
A. SHANKAR ◽  
SANDEEP ◽  
M. P. GHIMIRE ◽  
R. K. THAPA
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
Magnetic Moments ◽  
Full Potential ◽  
Local Spin Density Approximation ◽  
Heusler Compounds ◽  
Generalized Gradient ◽  
Half Metallic ◽  
Augmented Plane Wave ◽  
3D Elements

The structural optimization was followed by the calculation of electronic structure and magnetic properties on Co 2 CrAl and Co 2 CrGa . The structure optimization was based on generalized gradient approximation (GGA). The calculation of electronic structure was based on full potential linear augmented plane wave (FPLAPW) method within local spin density approximation (LSDA). We studied the electronic structure and magnetic properties. Results of density of states (DOS) and band structures shows that Co 2 CrAl and Co 2 CrGa are half-metallic ferromagnets (HMFS). The calculated magnetic moments of Co 2 CrAl and Co 2 CrGa are 2.915 and 3.075 μ B , respectively. We have calculated the onsite d–d coulomb and exchange interaction (U) For 3d elements like Co and Cr . The strongly localized d states were treated with LSDA+U method.

Thermoelectric and Half-Metallic Behavior of the Novel Heusler Alloy RbCrC: Ab initio DFT Study

SPIN ◽  
2020 ◽  
Vol 10 (04) ◽  
pp. 2050029
Author(s):  
M. Hammou ◽  
F. Bendahma ◽  
M. Mana ◽  
S. Terkhi ◽  
N. Benderdouche ◽  
...  
Keyword(s):  
Magnetic Moment ◽  
Debye Model ◽  
Total Magnetic Moment ◽  
Potential Candidate ◽  
Generalized Gradient ◽  
Half Metallicity ◽  
Electronic Band ◽  
Metallic Behavior ◽  
Half Metallic ◽  
Practical Applications

Research Highlights • Electronic, magnetic, elastic and thermoelectric properties of RbCrC alloy are investigated. • Material is half-metallic, ductile and anisotropic in nature. • The total magnetic moment (3[Formula: see text][Formula: see text]B) obeys the Slater–Pauling rule. • The HM RbCrC compound is identified as potential candidate for spintronic applications. • ZT calculated values of 0.89 and 0.94 make RbCrC a promising thermoelectric material candidate for use in future devices. The aim of this work is to investigate the half-metallicity behavior, elastic, thermodynamic and thermoelectric (TE) properties of the Heusler compound RbCrC using the generalized gradient approximation (GGA-PBE96) and the modified Becke–Johnson (mBJ) approach. The electronic band structures and density of states reveal that RbCrC is a half-metallic ferromagnet (HMF). The calculated total magnetic moment of 3[Formula: see text][Formula: see text]B follows the Slater–Pauling rule ([Formula: see text]). The half-metallicity character can be maintained in the 5.4–7.4 Å lattice constants range and the 0.8–1.2 [Formula: see text]/[Formula: see text] ratio range. Existence of half-metallic ferromagnetism in RbCrC makes it a promising material for practical applications in the spintronic field. Also, the RbCrC exhibits a ductile and anisotropic behavior. The quasi-harmonic Debye model (QHDM) is used to calculate the thermodynamic properties. The BoltzTraP code which is based on semi-classical Boltzmann theory (SCBT) is applied for calculating TE properties. According to the obtained figure of merit values (ZT between 0.89 and 0.94 from 50 K to 800 K), the RbCrC alloy remains a good candidate for thermoelectric applications.

First-principles calculations of electronic, magnetic and optical properties of HoN doped with TM (Ti, V, Cr, Mn, Co and Ni)

2018 ◽  
Vol 32 (05) ◽  
pp. 1850048
Author(s):  
M. Rouchdi ◽  
E. Salmani ◽  
M. Dehmani ◽  
H. Ez-Zahraouy ◽  
N. Hassanain ◽  
...  
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Magnetic Semiconductors ◽  
Dilute Magnetic Semiconductors ◽  
Magnetic Impurities ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Metallic Behavior ◽  
Half Metallic ◽  
Good Agreement

Using the first-principles calculations within the Korringa–Kohn–Rostoker (KKR) method combined with the coherent potential approximation (CPA), the structural, optical and magnetic properties of rare-earth nitride Ho[Formula: see text]TM[Formula: see text]N doped with transition metal (TM) atoms (Ti, V, Cr, Mn, Co and Ni) are investigated as a function the generalized gradient approximation and self-interaction correction (GGA–SIC) approximation. The optical properties are studied in detail by using ab-initio calculations. Using GGA–SIC we have showed that the bandgap value is in good agreement with the experimental value. Using GGA–SIC approximation for HoN, we have obtained a bandgap of 0.9 eV. Some of the dilute magnetic semiconductors (DMS) like Ho[Formula: see text]TM[Formula: see text]N under study exhibit a half-metallic behavior, which makes them suitable for spintronic applications. Moreover, the optical absorption spectra confirm the ferromagnetic stability based on the charge state of magnetic impurities.

Vacancy effects on the electronic structure of MgO compound

2015 ◽  
Vol 29 (25) ◽  
pp. 1550147 ◽  
Author(s):  
B. Merabet ◽  
S. Kacimi ◽  
A. Mir ◽  
M. Azzouz ◽  
A. Zaoui
Keyword(s):  
Electronic Structure ◽  
Oxygen Vacancy ◽  
Room Temperature ◽  
Magnetic Moments ◽  
Nearest Neighbors ◽  
Full Potential ◽  
Vacant Site ◽  
Spin Magnetic Moment ◽  
Augmented Plane Wave ◽  
Linearized Augmented Plane Wave

We have investigated the possibility to find [Formula: see text] ferromagnetism (FM) in the non-stoichiometric [Formula: see text] compound using the full potential linearized augmented plane wave [Formula: see text] method. We have examined the oxygen vacancy effect on the electronic structure of [Formula: see text] compound realizing the 128 atoms supercell. Our calculations predict that the cation vacancies cause the FM in [Formula: see text], where the magnetism is often created by the oxygen atoms nearest neighbors of the Mg vacant site, with a spin magnetic moment of 0.21 [Formula: see text]B/atom. We have reported a strong evidence of the existence of FM at room temperature, as we extended our studies to demonstrate the ability to induce intrinsic magnetic moments in MgO with cationic vacancies (Mg).

First-Principles Investigation of the Electronic Structure and Magnetic Properties for Co-Doped Fe3O4

2010 ◽  
Vol 654-656 ◽  
pp. 1678-1681
Author(s):  
Yu Hua Hou ◽  
Yu Jun Zhao ◽  
De Chang Zeng ◽  
Zhong Wu Liu ◽  
Li Shi Wen
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
Ground State ◽  
First Principles ◽  
Magnetic Moments ◽  
Ground State Structure ◽  
Site Preference ◽  
Generalized Gradient ◽  
Cobalt Ferrites ◽  
Strong Coulomb

The electronic structure and magnetic properties of the (Co1-xFex)Tet(CoxFe2-x)OctO4 spinels (x is defined as the degree of inversion) scenario are investigated theoretically from first-principles, using generalized gradient approximation (GGA) method for the systems with strong coulomb correlations, which gives a correct description of the electronic structure. The GGA+U method gives an improved qualitative result compared with the GGA not only for the excited-state properties such as energy gaps but also for the ground-state properties such as magnetic moments and crystal parameters. The nominal valence of the transition metal elements and the ground state structure have been established based on the study of variation of the cation distribution (x=0.0, 0.25, 0.5, 0.75 and 1.0) over the tetrahedral and octahedral sites. The site-preference calculation on bulk systems indicates that Co2+ ions strongly prefer the octahedral B sites, and the electronic structure and magnetic properties of cobalt ferrites highly depend on the cation distributions even though the chemical composition of the compound does not change. The results are in good agreement with the available experimental data and most of the other theoretical results.

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