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.

Magnetic Properties of Embedded Rh Clusters in Ni Matrix

1995 ◽  
Vol 384 ◽  
Author(s):  
Zhi-Qiang Li ◽  
Yuichi Hashi ◽  
Jing-Zhi Yu ◽  
Kaoru Ohno ◽  
Yoshiyuki Kawazoe
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Magnetic Moments ◽  
Functional Formalism ◽  
Rhodium Clusters ◽  
Spin Polarized ◽  
Local Density Functional

ABSTRACTThe electronic structure and magnetic properties of rhodium clusters with sizes of 1 - 43 atoms embedded in the nickel host are studied by the first-principles spin-polarized calculations within the local density functional formalism. Single Rh atom in Ni matrix is found to have magnetic moment of 0.45μB. Rh13 and Rhl 9 clusters in Ni matrix have lower magnetic moments compared with the free ones. The most interesting finding is tha.t Rh43 cluster, which is bulk-like nonmagnetic in vacuum, becomes ferromagnetic when embedded in the nickel host.

STABLE STRUCTURES, ELECTRIC AND MAGNETIC PROPERTIES OF NANOPARTICLES COn(n = 1-6) CLUSTERS: FIRST-PRINCIPLES CALCULATIONS

2013 ◽  
Vol 27 (15) ◽  
pp. 1362007
Author(s):  
JUN LIU ◽  
SHENG-BIAO TAN ◽  
HUI-NING DONG
Keyword(s):  
Magnetic Properties ◽  
Ground State ◽  
First Principles ◽  
Lower Energy ◽  
Magnetic Moments ◽  
Molecular Orbitals ◽  
First Principles Calculations ◽  
Half Metallicity ◽  
Ground State Structures ◽  
Stable Structures

The ground state geometric structures of the nanoparticles or clusters CO n(n = 1-6) were given based on the first-principles calculations. Then the magnetic properties of the clusters CO n(n = 1-6) and ( CO n)-2(n = 1-6) were calculated in system. Results show that their ground state structures are closely related to the numbers of O-ions. These clusters have no magnetic moments and half-metallicity if they are electroneutral. However, they have magnetic moments if they have positive or negative charges. The total magnetic moments of the clusters ( CO n)-2(n = 1-6, but n≠3) are all 2.0000 μB, and all their ions have contributions to the total magnetic moments. The main reason is that the molecular orbitals with lower energy filled with paired electrons and the molecular orbitals with higher energy are occupied by two electrons in parallel.

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.

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.

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.

Electronic Structure and Atomic Configuration of Extended Defects in Metals by First-Principles and Semiempirical TB-LMTO Methods

1997 ◽  
Vol 491 ◽  
Author(s):  
M. Šob ◽  
I. Turek ◽  
V. Vitek
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Magnetic Moments ◽  
Tight Binding ◽  
Local Environment ◽  
Ground State Structure ◽  
Full Potential ◽  
Extended Defects ◽  
Semiempirical Approach ◽  
Sphere Approximation

ABSTRACTWe present two tight-binding linear muffin-tin orbitals (TB-LMTO) techniques for electronic structure calculations of extended defects (such as grain boundaries, interphase interfaces, surface layers etc.) in metals. The first is based on the first-principles self-consistent surface Green's function approach within the atomic-sphere approximation (ASA) utilizing two-dimensional periodicity in the layers parallel to the interface. In the second approach the Hamiltonian is constructed within the TB-LMTO-ASA as well, but semiempirical terms are employed to characterize the repulsive part of the interaction and the effect of electrons in interstitial space. While the adjustable parameters have only been fitted to the properties of ideal ground state structure, the semiempirical approach describes correctly the structural energy differences, phonon frequencies etc. Two examples are presented: the electronic structure of the Σ = 5(210)/[001] tilt grain boundary in tungsten is determined and the sensitivity of 4d magnetic moments in thin films to local environment is discussed. A comparison of the semiempirical TB-LMTO-ASA with the first-principles full-potential LMTO results is performed along the trigonal deformation path connecting the bcc, simple cubic and fee structures and the applicability of the semiempirical approach for simulating atomic structure of extended defects is assessed.

First Principles Calculations of Magnetic Properties of LaMnO3 and La2/3 Al1/3 MnO3 Perovskite Manganites

2015 ◽  
Vol 754-755 ◽  
pp. 766-769
Author(s):  
A. Chik ◽  
S. Saad ◽  
F. Che Pa ◽  
C.K. Yeoh ◽  
R.M. Zaki
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
First Principles ◽  
Density Functional ◽  
Magnetic Moments ◽  
Perovskite Manganites ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation

The magnetic properties of the perovskite manganites LaMnO3(LMO) and La2/3Al1/3MnO3(LAMO) was presented. The calculations were made within density functional theory and generalized-gradient approximation (GGA) exchange correlations energy. It was found that LAMO exhibit magnetic properties and stabilizes in antiferromagnetic structure. However cell magnetization and magnetic moments reduce with inclusion of Al dopant.

Stability, electronic structure and magnetic properties of vacancy and nonmetallic atom-doped buckled arsenene: first-principles study

RSC Advances ◽  
2016 ◽  
Vol 6 (49) ◽  
pp. 43794-43801 ◽  
Author(s):  
Chunyan Xu ◽  
Mingfeng Zhu ◽  
Huiling Zheng ◽  
Xiaobo Du ◽  
Wenquan Wang ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Magnetic Moments ◽  
First Principles Study ◽  
Substitutional Doping

A doping C, Si, O and S can induce the magnetic moments of 1.0μBin buckled arsenene, while the substitutional doping of H, F, B, N and P can not produce the magnetism.

First principles study of the structural, electronic and optical properties of crystalline o-phenanthroline

2016 ◽  
Vol 30 (14) ◽  
pp. 1650077 ◽  
Author(s):  
Hajar Nejatipour ◽  
Mehrdad Dadsetani
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Binding Energies ◽  
Many Body ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Independent Particle ◽  
Excitonic Effects ◽  
Comprehensive Study

In a comprehensive study, structural properties, electronic structure and optical response of crystalline o-phenanthroline were investigated. Our results show that in generalized gradient approximation (GGA) approximation, o-phenanthroline is a direct bandgap semiconductor of 2.60 eV. In the framework of many-body approach, by solving the Bethe–Salpeter equation (BSE), dielectric properties of crystalline o-phenanthroline were studied and compared with phenanthrene. Highly anisotropic components of the imaginary part of the macroscopic dielectric function in o-phenanthroline show four main excitonic features in the bandgap region. In comparison to phenanthrene, these excitons occur at lower energies. Due to smaller bond lengths originated from the polarity nature of bonds in presence of nitrogen atoms, denser packing, and therefore, a weaker screening effect, exciton binding energies in o-phenanthroline were found to be larger than those in phenanthrene. Our results showed that in comparison to the independent-particle picture, excitonic effects highly redistribute the oscillator strength.

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