Comparative study of the electronic structure and optical properties of the Heusler alloys Co2MGa and Co2MAl (M = Fe and Ni)

2021 ◽  
Author(s):  
E. I. Shreder ◽  
A. A. Makhnev ◽  
K. G. Suresh ◽  
M. G. Kostenko ◽  
E. D. Chernov ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Spin Polarization ◽  
Energy Gap ◽  
Magnetic Moments ◽  
Heusler Alloys ◽  
Complex Dielectric Constant ◽  
Spectral Parameters ◽  
Spectrum Region ◽  
Good Agreement

The electronic structure and optical properties of the Heusler alloys Co2NiGa, Co2NiAl, Co2FeGa, and Co2FeAl are reported and compared in this work. In the Fe-based alloys, Co2FeGa and Co2FeAl, the electronic structure is found to have 100% spin polarization with the indirect energy gap in the [Formula: see text]-[Formula: see text] direction, whereas in Co2NiGa and Co2NiAl, the density of states is metallic in both spin projections with spin polarization of 55% (Co2NiGa) and 37% (Co2NiAl). Total and Co partial magnetic moments of all Heusler alloys for the optimized lattice parameters were found in a good agreement with previous calculations and experimental data. The frequency dependence of the real and imaginary parts of the complex dielectric constant for the Heusler alloys is studied in the spectrum region of 0.08–5 eV. The research results are discussed based on the performed calculations of the electronic structure. It was found that the character of variations of the spectral parameters of the alloys is typical for media with the metallic conductivity. In the IR region, the mechanism of the intraband acceleration of electrons by the light wave field dominates. The significant changes in the optical spectrum, magnetic moment, spin polarization and electronic structure were revealed in Co2MGa and Co2MAl for different M atoms which motivate further investigations of the Co-based Heusler alloys as promising materials for spintronics.

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 OPTICAL PROPERTIES OF CRYSTALLINE C60

1992 ◽  
Vol 06 (06) ◽  
pp. 309-321 ◽  
Author(s):  
W.Y. CHING ◽  
MING-ZHU HUANG ◽  
YONG-NIAN XU ◽  
FANQI GAN
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Optical Spectrum ◽  
Local Density ◽  
Low Dielectric Constant ◽  
Experimental Measurements ◽  
Absorption Bands ◽  
Low Dielectric ◽  
Good Agreement

The electronic structure and optical properties of crystalline C 60 and their pressure dependence have been studied by first-principles local density calculations. It is shown that fcc C 60 has a low dielectric constant and an optical spectrum rich in structures. The spectrum shows five disconnected absorption bands in the 1.4 to 7.0 eV region with sharp structures in each band that can be attributed to critical point transitions. This is a manifestation of the localized molecular structure coupled with long range crystalline order unique to the C 60 crystal. At a sufficient high pressure, the structures in the optical spectrum start to merge due to the merging of the bands. These results are in good agreement with some recent experimental measurements.

Structural, elastic, magnetic and electronic properties of Ti-based Heusler alloys

2020 ◽  
Vol 34 (07) ◽  
pp. 2050055 ◽  
Author(s):  
R. Murugeswari ◽  
M. Manikandan ◽  
R. Rajeswarapalanichamy ◽  
A. Milton Franklin Benial
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Energy Gap ◽  
Ambient Pressure ◽  
Magnetic Moments ◽  
Heusler Alloys ◽  
Text Structure ◽  
Simulation Code ◽  
Text Type ◽  
Lattice Constants

The structural, elastic, magnetic and electronic properties of titanium-based alloys [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] are investigated by the first-principles calculations based on density functional theory using the Vienna ab-initio simulation code. The lattice constants of [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] alloys are optimized for the two possible structures such as [Formula: see text] and [Formula: see text]. It is found that at ambient pressure [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] alloys are stable in [Formula: see text]-type crystal structure. The total magnetic moments [Formula: see text] and the energy gap [Formula: see text] of [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] alloys are calculated for various pressures. The total magnetic moments of [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] alloys in [Formula: see text] structure follow the rule [Formula: see text] and agree with the Slater–Pauling (SP) curve quite well. In both structures [Formula: see text] and [Formula: see text], the calculated magnetic moment of [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] alloys decreases with increase in pressure. Density of states shows the metallic nature of [Formula: see text] [Formula: see text], [Formula: see text] and [Formula: see text] alloys in [Formula: see text] structure and half-metallic [Formula: see text] behavior in [Formula: see text] structure, i.e., majority spin channel is strongly metallic and the minority spin maintains the gap at the Fermi level at the equilibrium lattice constant.

scholarly journals Effect of Electronic Correlations on the Electronic Structure, Magnetic and Optical Properties of the Ternary RCuGe Compounds with R = Tb, Dy, Ho, Er

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3536
Author(s):  
Alexey V. Lukoyanov ◽  
Lubov N. Gramateeva ◽  
Yury V. Knyazev ◽  
Yury I. Kuz’min ◽  
Sachin Gupta ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Theoretical Calculations ◽  
Rare Earth Ions ◽  
Local Spin Density Approximation ◽  
Electron Correlations ◽  
Absorption Region ◽  
Densities Of States ◽  
Interband Light Absorption ◽  
Good Agreement

In this study, the ab initio and experimental results for RCuGe ternary intermetallics were reported for R = Tb, Dy, Ho, Er. Our theoretical calculations of the electronic structure, employing local spin density approximation accounting for electron–electron correlations in the 4f shell of Tb, Dy, Ho, Er ions were carried in DFT+U method. The optical properties of the RCuGe ternary compounds were studied at a broad range of wavelengths. The spectral and electronic characteristics were obtained. The theoretical electron densities of states were taken to interpret the experimental energy dependencies of the experimental optical conductivity in the interband light–absorption region. From the band calculations, the 4f shell of the rare-earth ions was shown to provide the major contribution to the electronic structure, magnetic and optical properties of the RCuGe intermetallics. The accounting for electron–electron correlations in Tb, Dy, Ho, Er resulted in a good agreement between the calculated and experimental magnetic and optical characteristics.

Influence of Co and Mn substitution on magnetic properties of novel Y2FeSi Heusler alloy

2021 ◽  
Vol 35 (05) ◽  
pp. 2150088
Author(s):  
G. Kasprzak ◽  
J. Rzacki
Keyword(s):  
Magnetic Properties ◽  
Spin Polarization ◽  
Magnetic Moment ◽  
Density Functional ◽  
Magnetic Moments ◽  
Heusler Alloys ◽  
Total Magnetic Moment ◽  
Functional Theory ◽  
Structure Changes ◽  
Mn Substitution

This paper presents results of density functional theory (DFT) studies on structural, electronic, and magnetic properties of novel Y2FeSi Heusler material characterized by spin polarization at Fermi level of [Formula: see text] and magnetic moment of 1.56 [Formula: see text]. The total magnetic moment of investigated material is dominated by Iron sites, while magnetic moments coming from Yttrium sites are aligned antiparallel to the Iron. Here, we introduced Co and Mn substitutions to alter the magnetic and electronic properties of the studied material. The Heusler alloys are very sensitive to electronic structure changes induced by ionic substitutions, which allowing to specifically modulate their properties. The Co-substitution lowered the total magnetic moment to [Formula: see text][Formula: see text]1.20 [Formula: see text] and Mn caused a rise to [Formula: see text][Formula: see text]1.93 [Formula: see text]. Introduction of Mn resulted in [Formula: see text] spin polarization. We hope that this study will promote further theoretical as well as experimental interest in these types of compounds.

Electronic structure and magnetic, electrical and optical properties of ferromagnetic Heusler alloys

1987 ◽  
Vol 70 (1-3) ◽  
pp. 33-38 ◽  
Author(s):  
M.J. Otto ◽  
H. Feil ◽  
R.A.M. Van Woerden ◽  
J. Wijngaard ◽  
P.J. Van Der Valk ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Heusler Alloys ◽  
Electrical And Optical Properties

Electronic Structure and Associated Optical Properties of LAPO4:Ce

1994 ◽  
Vol 348 ◽  
Author(s):  
K. C. Mishra ◽  
K. H. Johnson
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Green Emission ◽  
Scattered Wave ◽  
Cluster Approach ◽  
Small Magnitude ◽  
Lanthanum Phosphate ◽  
Consistent Field ◽  
Self Consistent Field ◽  
Good Agreement

ABSTRACTLanthanum phosphate activated by cerium and terbium is a well known lamp phosphor which is used for its green emission. In this paper, we have investigated the electronic structure and associated optical properties of lanthanum phosphate doped with cerium using the self consistent field scattered wave molecular orbital cluster approach. Relativistic corrections are included for the lanthanum and cerium centered clusters. In spite of the small magnitude of crystal field splitting, a significant admixture of the f-like orbitals with the ligand orbitals is observed for cerium. The optical transitions are calculated using the transition state formalism. The absorption peaks due to electronic transition from the f-like states to d-like states of cerium are found to be 271 rim, 259 nm, 245 nm, 208 nm and 194 nm which are in good agreement with the experiment. The nature of the band gap transition in lanthanum phosphate is also discussed.

Band Structure and Optical Properties of CuInSe2

2014 ◽  
Vol 894 ◽  
pp. 254-258
Author(s):  
Rong Zhen Chen ◽  
Clas Persson
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Coupling Effect ◽  
Full Potential ◽  
Spin Orbit Coupling ◽  
Generalized Gradient ◽  
Augmented Plane Wave ◽  
Generalized Gradient Approximation ◽  
Linearized Augmented Plane Wave ◽  
Good Agreement

In this work, the electronic structure and dielectric function of chalcopyrite CuInSe2 are presented. The results are based on the full-potential linearized augmented plane wave (FPLAPW) method using the generalized gradient approximation (GGA) plus an onsite Coulomb interaction U of the Cu d states. The dielectric constant, absorption coefficient and refractive index are explored by means of optical response. The spin-orbit coupling effect is considered for the calculations of electronic structure and optical properties. We find that the results based on our calculation method have good agreement compared with experimental and other earlier simulations results.

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