Magnetic moment and atomic volume in supersaturated Fe–Cu solid solutions: Ab initiocalculations compared with experiments

2000 ◽  
Vol 15 (3) ◽  
pp. 653-658 ◽  
Author(s):  
Wenqing Zhang ◽  
E. Ma
Keyword(s):  
Ab Initio ◽  
Solid Solutions ◽  
Magnetic Moment ◽  
High Spin State ◽  
Atomic Volume ◽  
Heat Of Mixing ◽  
Full Potential ◽  
Face Centered Cubic ◽  
Generalized Gradient ◽  
Pronounced Increase

The properties of nonequilibrium face-centered-cubic (fcc) and body-centered-cubic (bcc) Fe–Cu alloys were studied using the first-principles full-potential linearized augmented plane wave method within the generalized gradient approximation. The ab initio calculation results are compared quantitatively with the magnetic moment and atomic volume observed for mechanically alloyed FexCu100–x (x = 0 to 100) supersaturated bcc and fcc solid solutions. The calculations show that Cu alloying leads to a small enhancement of the magnetic moment of bcc Fe. The fcc Fe moment, on the other hand, experiences a more pronounced increase into a high-spin state upon alloying with Cu. It reaches approximately the same value as that in the bcc alloys for all Cu concentrations where fcc solutions are obtained in experiments, corroborating previous ab initio calculations using different methods. The magnetic moment increases are accompanied by an atomic volume expansion. Both the calculated moment and volume behavior are in good agreement with those measured for fcc and bcc Fe–Cu solutions. The magnetovolume expansion upon magnetic interaction between the alloyed Fe and Cu, rather than the positive heat of mixing, constitutes the primary reason for the atomic volume increase observed.

Electronic Structure Of (AgSb)xPbn-2xTen

2003 ◽  
Vol 793 ◽  
Author(s):  
Daniel I Bilc ◽  
S.D. Mahanti ◽  
M.G. Kanatzidis
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Two Component System ◽  
Functional Theory ◽  
Covalent Interaction ◽  
Salt Structure ◽  
Linearized Augmented Plane Wave

ABSTRACTComplex quaternary chalcogenides (AgSb)xPbn-2xTen (0<x<n/2) are thought to be narrow band-gap semiconductors which are very good candidates for room and high temperature thermoelectric applications. These systems form in the rock-salt structure similar to the well known two component system PbTe (x=0). In these systems Ag and Sb occupy Pb sites randomly although there is some evidence of short-range order. To gain insights into the electronic structure of these compounds, we have performed electronic structure calculations in AgSbTe2 (x=n/2). These calculations were carried out within ab initio density functional theory (DFT) using full potential linearized augmented plane wave (LAPW) method. The generalized gradient approximation (GGA) was used to treat the exchange and correlation potential. Spinorbit interaction (SOI) was incorporated using a second variational procedure. Since it is difficult to treat disorder in ab initio calculations, we have used several ordered structures for AgSbTe2. All these structures show semimetallic behavior with a pseudogap near the Fermi energy. Te and Sb p orbitals, which are close in energy, hybridize rather strongly indicating a covalent interaction between Te and Sb atoms.

THE POSSIBILITY OF TWO MAGNETIC STATES IN Co19 CLUSTER

1996 ◽  
Vol 03 (01) ◽  
pp. 453-456
Author(s):  
KEEYUNG LEE
Keyword(s):  
High Spin ◽  
Spin State ◽  
Magnetic Moment ◽  
High Spin State ◽  
Local Magnetic Moment ◽  
Orbital Method ◽  
Face Centered Cubic ◽  
Spin Moment ◽  
Transition Metal Clusters ◽  
Magnetic States

The possibility of more than one magnetic state has been explored for the face-centered-cubic Co19 cluster using the local spin-density linear combination of the Gaussian orbital method. Fixed moment calculations were done and the converged states were used as an input potential to obtain self-consistent solutions. Two different magnetic states with the magnetic moment per atom of 1.00 μB and 2.05 μB were obtained. The high-spin moment state has lower energy and is considered the ground state, and the low spin moment a metastable state. The local magnetic moment of the center, first- and second-shell atoms are found to be 1.90, 1.64, and −0.72 μB respectively for the low spin state, and 1.87, 1.92, and 2.01 μB respectively for the high spin state. Considering that the center-site atom has shown slow convergence to bulk moment for other transition-metal clusters in previous studies, Co clusters are found to be exceptional as far as this property is concerned. Density of states (DOS) of the cluster and bulk have been compared after the cluster levels were Gaussian-broadened. The DOS similarity between cluster and bulk is also found to be reasonably good.

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.

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.

Ab initio investigation of the structural, electronic, magnetic and optical properties of the perovskite TlMnX3 (X = F, Cl) compounds

2016 ◽  
Vol 30 (07) ◽  
pp. 1650031 ◽  
Author(s):  
Farida Hamioud ◽  
Ghadah S. AlGhamdi ◽  
Saleh Al-Omari ◽  
A. A. Mubarak
Keyword(s):  
Ab Initio ◽  
Energy Gap ◽  
Optical Spectra ◽  
Index Formula ◽  
Full Potential ◽  
Generalized Gradient ◽  
Augmented Plane Wave ◽  
Semiconductor Behavior ◽  
Technology Applications ◽  
Linearized Augmented Plane Wave

We have performed ab initio investigation of some physical properties of the perovskite TlMnX3 (X = F, Cl) compounds using the full-potential linearized augmented plane wave (FP-LAPW) method. The generalized gradient approximation (GGA) is employed as exchange-correlation potential. The calculated lattice constant and bulk modulus agree with previous studies. Both compounds are found to be elastically stable. TlMnF3 and TlMnCl3 are classified as anisotropic and ductile compounds. The calculations of the band structure of the studied compounds showed the semiconductor behavior with the indirect (M–X) energy gap. Both compounds are classified as a ferromagnetic due to the integer value of the total magnetic moment of the compounds. The different optical spectra are calculated from the real and the imaginary parts of the dielectric function and connected to the electronic structure of the compounds. The static refractive index [Formula: see text] is inversely proportional to the energy bandgap of the two compounds. Beneficial optics technology applications are predicted based on the optical spectra.

scholarly journals Ab initio investigation of the atomic volume, thermal expansion, and formation energy of WTi solid solutions

2021 ◽  
Vol 5 (4) ◽  
Author(s):  
R. Bodlos ◽  
T. Dengg ◽  
A. V. Ruban ◽  
M. Dehghani ◽  
L. Romaner ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Ab Initio ◽  
Solid Solutions ◽  
Formation Energy ◽  
Atomic Volume

AB INITIO STUDY OF THE ELECTRONIC AND MAGNETIC PROPERTIES OF GRAPHENE WITH AND WITHOUT ADSORPTION OF M ATOM (M = C, N, O, F, Cl)

2018 ◽  
Vol 25 (03) ◽  
pp. 1850069 ◽  
Author(s):  
ALI I. ISMAIL ◽  
A. A. MUBARAK
Keyword(s):  
Magnetic Properties ◽  
Ab Initio ◽  
Graphene Sheet ◽  
Local Density ◽  
Magnetic Moments ◽  
Graphene Sheets ◽  
Full Potential ◽  
Ab Initio Study ◽  
Generalized Gradient ◽  
Adsorbed Atoms

We present here an ab initio study for the energetic, electronic, magnetic and optical structures of the graphene sheet with and without the adsorption of M atom (M [Formula: see text] C, N, O, F, Cl). The calculations are preformed using the full-potential linearized augmented plane wave (FP-LAPW) within the generalized gradient approximation (GGA) to describe the exchange-correlation potential. The calculations show that N prefers the bridge site, while C, O, F and Cl prefer the top site above the graphene sheet. The calculated M-graphene bond length is found to be inversely proportional to the adsorption energy. The hybridization between sp-states of the graphene sheet and M adatom is determined by the analysis of the partial and local density of states (PDOS and TDOS). In case of O and F as adsorbed atoms, graphene sheets show a wide energy band-gap and some significant magnetic moments. The optical properties of the studied sheets are performed in different radiation regions using the real and imaginary parts of the dielectric function. We think that the energetic, electronic, optical and magnetic properties of the M-graphene sheets are governed by two main factors; the number of unpaired valence electrons and the electronegativity of the M atom.

Ab Initio Investigation of Structural, Electronic, Magnetic and Mechanical Properties of Fe2NiAl1−xGax New Heusler Alloys

SPIN ◽  
2020 ◽  
Vol 10 (03) ◽  
pp. 2050019
Author(s):  
A. Benkaddour ◽  
O. Cheref ◽  
N. Benkhettou ◽  
N. Mehtougui ◽  
D. Rached ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ab Initio ◽  
Magnetic Moments ◽  
Heusler Alloys ◽  
Plane Waves ◽  
Full Potential ◽  
Generalized Gradient ◽  
Metallic Behavior ◽  
Parameter Values ◽  
Good Agreement

This work presents ab initio study of the structural, electronic, magnetic and mechanical properties of Fe2NiAl[Formula: see text]Gax Heusler compounds with variable concentrations ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]) of Ga. Calculations have performed using the full-potential linearized augmented plane waves (FP-LAPW) method within generalized gradient approximation Perdew–Burke–Ernzerhof (GGA-PBE) formalism in order to describe the exchange–correlation potential. The obtained results showed that the equilibrium parameter values are in good agreement with the available experimental results. In the study of the electronic properties, band structure analysis indicated that all of our compounds have metallic behavior. The calculated total magnetic moments of our Heusler alloys are in line with the Slater–Pauling rule, and they agreed with the results of previous studies. For mechanical properties, shear modulus, Young’s modulus, elastic constants, Poisson’s ratio and shear anisotropy factor have studied. Their obtained values reveal that these compounds are mechanically and dynamically stable.

Ru2Ti1-xFexGe: Novel candidate for the spintronic applications

2015 ◽  
Vol 29 (09) ◽  
pp. 1550057
Author(s):  
A. Hamri ◽  
Z. Dridi ◽  
B. Hamri ◽  
A. Hallouche
Keyword(s):  
Magnetic Moment ◽  
Heusler Alloys ◽  
Exchange Potential ◽  
Full Potential ◽  
Generalized Gradient ◽  
Half Metallic ◽  
Augmented Plane Wave ◽  
Generalized Gradient Approximation ◽  
First Time ◽  
Linearized Augmented Plane Wave

The mechanical, electronic and magnetic properties of the full heusler alloys Ru 2 Ti 1-x Fe x Ge for the concentrations x = 0, 0.25, 0.5, 0.75, 1 using WIEN2k implementation of full potential linearized augmented plane wave (FP-LAPW) method in order to find a new compound for the spintronic applications within generalized gradient approximation (GGA) and modified Becke Johnson exchange potential with generalized gradient approximation (MBJ-GGA) as exchange correlation (XC) potential are reported for the first time. Our results show that the Fe incorporating in the Ru 2 TiGe created a half metallic (HM) gap at Fermi level (EF) in minority spin channel (MIC) and induced a magnetic moment on the paramagnetic Ru 2 TiGe . Moreover, the HM gap decreases with increasing the concentrations from 0.25 to 0.75, while the magnetic moment undergoes an inverse behavior.

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