Optical Properties of the Half-Metallic La3/4Ca1/4MnO3

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3359-3364
Author(s):  
D. Bagayoko ◽  
G. L. Zhao ◽  
J. D. Fan ◽  
J. T. Wang
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Optical Conductivity ◽  
Local Density ◽  
Metallic Phase ◽  
Ferromagnetic Phase ◽  
Metallic State ◽  
Average Magnetic Moment ◽  
Half Metallic ◽  
Experimental Values

We studied the electronic structure and optical properties of the low temperature (T = 0 K for the calculation) ferromagnetic phase of La3/4Ca1/4MnO3 using a self-consistent ab-initio LCAO method. We employed a local density potential. The calculated electronic structure suggests that the material is in a half-metallic state. The calculated average magnetic moment for the half-metallic phase is 3.75 μ B per Mn. This value is very close to the experimental values of 3.7 μ B per Mn. The real part of the optical conductivity, σ1(ω), from the direct band transitions, is predicted. The calculated optical conductivity shows that for photon energies below 2.4 eV, the electronic states of minority spin do not contribute to the optical transitions.

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.

scholarly journals Электронная структура и оптические спектры соединений GdFeAl и GdFeSi

2021 ◽  
Vol 63 (6) ◽  
pp. 700
Author(s):  
Ю.В. Князев ◽  
А.В. Лукоянов ◽  
Ю.И. Кузьмин ◽  
А.Г. Кучин ◽  
С.П. Платонов
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Comparative Analysis ◽  
Optical Conductivity ◽  
Electronic States ◽  
Wavelength Interval ◽  
Correlation Effects ◽  
Calculated Density ◽  
Density Of Electronic States ◽  
Conductivity Spectra

Results of investigations of electronic structure and optical properties of GdFeAl and GdFeSi compounds are presented. Spin-plarized density of states and interband optical conductivity spectra were calculated in frame of DFT+U technique with a correction for strong correlation effects in 4f shell of Gd. Optical properties were measured by ellipsometric technique in wavelength interval of 0.22 – 16 μm. Nature of quantum light absorption is discussed on the base of comparative analysis of experimental and calculated spectra. It is shown that main features of frequency dependencies of the optical conductivity are interpret qualitatively by the calculated density of electronic states.

Effect of strain on the electronic structure and optical properties of germanium

2018 ◽  
Vol 32 (12) ◽  
pp. 1850140 ◽  
Author(s):  
Shumin Wen ◽  
Chunwang Zhao ◽  
Jijun Li ◽  
Qingyu Hou
Keyword(s):  
Dielectric Constant ◽  
Optical Properties ◽  
Optical Conductivity ◽  
Density Functional ◽  
Tensile Strain ◽  
Local Density ◽  
Compressive Strain ◽  
Static Dielectric Constant ◽  
Functional Theory ◽  
Screened Exchange

The effects of biaxial strain parallel to the (001) plane on the electronic structures and optical properties of Ge are calculated using the first-principles plane-wave pseudopotential method based on density functional theory. The screened-exchange local-density approximation function was used to obtain more reliable band structures, while strain was changed from −4% to [Formula: see text]4%. The results show that the bandgap of Ge decreases with the increase of strain. Ge becomes a direct-bandgap semiconductor when the tensile strain reaches to 2%, which is in good agreement with the experimental results. The density of electron states of strained Ge becomes more localized. The tensile strain can increase the static dielectric constant distinctly, whereas the compressive strain can decrease the static dielectric constant slightly. The strain makes the absorption band edge move toward low energy. Both the tensile strain and compressive strain can significantly increase the reflectivity in the range from 7 eV to 14 eV. The tensile strain can decrease the optical conductivity, but the compressive strain can increase the optical conductivity significantly.

Optical Properties and Electronic Structure of LaNi5-XCux (x=0–1.2) Intermetallic System

2010 ◽  
Vol 168-169 ◽  
pp. 529-532 ◽  
Author(s):  
Yu.V. Knyazev ◽  
Y.I. Kuz’min ◽  
A.V. Lukoyanov ◽  
Anatoly G. Kuchin
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Optical Conductivity ◽  
Theoretical Calculations ◽  
Generalized Gradient ◽  
Broad Absorption ◽  
Generalized Gradient Approximation ◽  
Electron Transitions ◽  
Intermetallic System ◽  
Conductivity Spectra

Optical properties of the LaNi5-xCux (x = 0, 0.6, 1, 1.2) compounds were studied. It was shown that substitution of copper for nickel led to noticeable changes in the optical conductivity spectra. Calculations of the electronic structure of compounds with x = 0, 1, 2 were performed using a generalized gradient approximation. The interband optical conductivity of these intermetallics was calculated. The optical ellipsometrical measurements and theoretical calculations testify to the appearance of a broad absorption structure associated with the Cu 3d  Ni 3d electron transitions and increasing with the growth of copper content.

scholarly journals First Principles Study on Electronic Structure and Optical Properties of PMMA Doped InSb–Mn Alloy Polymer Matrix Composite

2022 ◽  
Vol 2022 ◽  
pp. 1-6
Author(s):  
Dhanabalakrishnan Kovilpalayam Palaniswamy ◽  
Pandiyan Arumugan ◽  
Ravindiran Munusami ◽  
A Chinnasamy ◽  
S. Madhu ◽  
...  
Keyword(s):  
Thin Film ◽  
Optical Properties ◽  
Electronic Structure ◽  
Absorption Coefficient ◽  
Band Gap ◽  
Optical Conductivity ◽  
First Principles ◽  
Dft Method ◽  
Optical Absorption Coefficient ◽  
Group Iii

InSb the group III-V semiconductor with narrow band gap is combined with Mn in various concentrations and that InSb–Mn alloy is doped with poly methyl methacrylate (PMMA). The optical properties and electronic structure of ternary InSb–Mn alloy with PMMA are investigated by first principles calculations using the DFT method. Varying Mn concentrations play an important role in the improvement of the absorption coefficient and optical conductivity. It is observed that the band gap of InSb–Mn: PMMA decreases monotonously with the increase in Mn concentration. Optical properties of InSb–Mn: PMMA, such as the optical absorption coefficient and optical conductivity, are greater than those of pure InSb. InSb–Mn: PMMA alloy is doped with PMMA polymer in order to make a thin film as PMMA is a transparent thermoplastic polymer. These results suggest a promising application of InSb–Mn: PMMA thin film in optoelectronics when the InSb doping is 24% with improved conductivity when compared with other doping ratios. This states the optimum doping ratio and the major finding in the carried out research based on modelling and simulation.

scholarly journals Electronic structure and optical properties of (BeTe)n/(ZnSe)m superlattices

2016 ◽  
Vol 34 (1) ◽  
pp. 115-125 ◽  
Author(s):  
M. Caid ◽  
H. Rached ◽  
D. Rached ◽  
R. Khenata ◽  
S. Bin Omran ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Electronic Structure ◽  
Ground State ◽  
Optical Constants ◽  
Local Density ◽  
Band Gaps ◽  
Full Potential ◽  
Density Approximation ◽  
Binary Compounds

AbstractThe structural, electronic and optical properties of (BeTe)n/(ZnSe)m superlattices have been computationally evaluated for different configurations with m = n and m≠n using the full-potential linear muffin-tin method. The exchange and correlation potentials are treated by the local density approximation (LDA). The ground state properties of (BeTe)n/(ZnSe)m binary compounds are determined and compared with the available data. It is found that the superlattice band gaps vary depending on the layers used. The optical constants, including the dielectric function ε(ω), the refractive index n(ω) and the refractivity R(ω), are calculated for radiation energies up to 35 eV.

Theoretical Study of a Novel Infrared Nonlinear Optical Crystal of BaGa4S7

2020 ◽  
Vol 15 (11) ◽  
pp. 1395-1405
Author(s):  
Qiao Wu ◽  
Rong Dai ◽  
Lei Zhang ◽  
Wei Wang ◽  
Fuchun Zhang ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Electronic Structure ◽  
Nonlinear Optical ◽  
Laser Damage Threshold ◽  
Nonlinear Optical Crystal ◽  
Electron Contribution ◽  
Orbital Electron ◽  
Optical Crystal ◽  
Experimental Values

The first-principles calculation based on density functional theory, the electronic structure and optical properties of BaGa4S7 (BGS) were systematically investigated by using generalized gradient approximation (GGAPBE) and hybrid functional method (HSE06). The results showed that the theoretical results from the HSE06 method coincided well with the experimental values. Geometry optimization showed that the theoretical lattice parameters of the BGS were also in agreement with the experimental values. Furthermore, the results of the electronic structure showed that the BGS is a nonlinear optical crystal with a wide direct bandgap energy value, as the bandgap width obtained by the HSE06 method was 3.54 eV, which was in accordance with the experimental values. The band structure and density values of state calculations showed that the top of the valence band was mainly composed of S-3p orbital and Ga-4s, 4p orbital electron contribution. On the other hand, the bottom of the conduction band was mainly composed of Ga-4s, 4p, S-3p, and Ba-5d orbital electron contribution, showing that the orbital coupling between Ga and S atoms determined the optical properties of the BGS, while the contribution of Ba atoms to the optical properties was small. The optical properties obtained from the calculation results showed that the crystal material had strong absorption and reflection characteristics in the ultraviolet band, good transmittance in the infrared area, average static dielectric constant, and an average refractive index of 2.873, 1.69, respectively. Moreover, the static double refractive index was 0.07, showing that BGS crystal materials had excellent phase matching performance in a wider range of wavelengths, with a high laser damage threshold. These results proved that the BGS could be a promising material for IR nonlinear optical crystals.

Electronic structure and optical properties of CsSnI3−yBry (y = 0, 1, 2, 3) perovskites

2019 ◽  
Vol 33 (04) ◽  
pp. 1950003 ◽  
Author(s):  
R. Padmavathy ◽  
A. Amudhavalli ◽  
R. Rajeswarapalanichamy ◽  
K. Iyakutti
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Density Functional ◽  
Energy Gap ◽  
Phonon Dispersion ◽  
Bromine Atom ◽  
Low Cost ◽  
Normal Pressure ◽  
Metallic Phase ◽  
Halide Perovskites

The halide perovskites-based solar cells have been attractive due to their excellent power conversion efficiency and low cost. The structural, electronic and optical properties of Sn-based cesium halide perovskites CsSnI[Formula: see text]Br[Formula: see text] (y = 0, 1, 2, 3) are investigated based on density functional theory. The computed electronic structure profile of CsSnI[Formula: see text]Br[Formula: see text] (y = 0, 1, 2, 3) reveals that these materials exhibit semiconducting behavior at normal pressure. The energy gap of CsSnI3 is tuned by the substitution of bromine atom for iodine atom. Also, it is found that the energy gap values of these materials decrease with increase in pressure and a semiconductor to metallic phase transition is observed at high pressure. The optical properties of these Sn-based halide perovskite compounds against the incident photon energy radiation indicate that these materials can be effective candidates for solar cell applications. The dynamical stability of these perovskites is analyzed by phonon dispersion curve.

scholarly journals THE ANOMALOUS METALLIC FERROMAGNETIC STATE OF Sr DOPED MANGANITES

2001 ◽  
Vol 15 (23) ◽  
pp. 1031-1040 ◽  
Author(s):  
V. FERRARI ◽  
M. J. ROZENBERG ◽  
R. WEHT
Keyword(s):  
Density Of States ◽  
Optical Conductivity ◽  
Low Temperatures ◽  
Ferromagnetic State ◽  
Ferromagnetic Phase ◽  
Metallic State ◽  
Natural Explanation ◽  
Doped Manganites

We deduce a model relevant for the anomalous metallic state of Sr doped manganites at low temperatures within the ferromagnetic phase. It provides a natural explanation for several anomalous features observed experimentally, such as the small Drude contribution in optical conductivity, the "pseudo-gap" in the density of states, and the unusual dispersion observed in photoemission.

Electronic and Optical Properties of Cubic Perovskites CsPbCl3−yIy (y = 0, 1, 2, 3)

2019 ◽  
Vol 74 (10) ◽  
pp. 905-913 ◽  
Author(s):  
R. Padmavathy ◽  
A. Amudhavalli ◽  
R. Rajeswarapalanichamy ◽  
K. Iyakutti
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Density Functional ◽  
Energy Gap ◽  
Phonon Dispersion ◽  
Low Cost ◽  
Normal Pressure ◽  
Metallic Phase ◽  
Halide Perovskites ◽  
Gap Values

AbstractLead-based halide perovskites are attractive substrates for solar cells because of their excellent power conversion efficiency and low cost. The ground-state properties, electronic structure, as well as optical and phonon properties of lead-based halide perovskites (CsPbCl3−yIy (y = 0, 1, 2, 3) are investigated by first-principles calculations based on density functional theory. Their electronic structure indicates that CsPbCl3−y Iy (y = 0, 1, 2, 3) compounds exhibit semiconducting behaviour at normal pressure. The energy gap of CsPbCl3 can be tuned by substituting iodine atoms for chlorine atoms. The energy gap values are found to be 3.06, 2.681, 2.330, and 2.030 eV using HSE06 calculations for CsPbCl3, CsPbCl2I, CsPbClI2, and CsPbI3, respectively. Also, it is found that the energy gap values of these materials decrease with increase in pressure and that a semiconductor-to-metallic phase transition is observed at high pressure. The optical properties of these Pb-based compounds are analysed. The dynamical stability of these perovskites is analysed by their phonon dispersion curves.

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