Role of Cr-d states in the electronic and optical properties of the CdCr2X4 (X = S, Se) normal ferromagnetic spinels using PBE+U and TB-mBJ potentials

We have investigated theoretically the role of Cr-d states in the electronic and optical properties of the CdCr2X4 (X = S, Se) normal ferromagnetic spinels using the framework of an all-electron full-potential linearized augmented plane wave method. The calculations are performed using Coulomb corre...

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Bibliographic Details
Published inJournal of materials research Vol. 32; no. 12; pp. 2431 - 2437
Main Authors Samanta, Saurabh, Saini, Sapan Mohan
Format Journal Article
LanguageEnglish
Published New York, USA Cambridge University Press 28.06.2017
Springer International Publishing
Springer Nature B.V
Subjects
Applied and Technical Physics
Approximation
Biomaterials
Coulomb friction
Dielectric properties
Electron spin
Electrons
Energy
Energy consumption
Energy gap
Ferromagnetism
Inorganic Chemistry
Lattice parameters
Materials Engineering
Materials research
Materials Science
Mathematical analysis
Methods
Nanotechnology
Optical properties
Reflectance
Refractivity
Semiconductors
Spin-orbit interactions
Splitting
Studies
Theory
optical properties
magnetic properties
electronic structure
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Summary:We have investigated theoretically the role of Cr-d states in the electronic and optical properties of the CdCr2X4 (X = S, Se) normal ferromagnetic spinels using the framework of an all-electron full-potential linearized augmented plane wave method. The calculations are performed using Coulomb corrected Perdew–Burke–Ernzerhof (PBE+U) and Tran–Blaha modified-Becke–Johnson (TB-mBJ) approximations with the adding of spin–orbit coupling in both schemes. The lattice parameters have been optimized and are in agreement with the existing experimental values. We found band gap values 1.606 eV and 0.972 eV of CdCr2X4 (X = S, Se), respectively, using the TB-mBJ scheme. Analysis of the site and momentum projected densities shows that the larger splitting of Cr-d states is responsible for the larger band gap by the use of the TB-mBJ scheme. Optical properties along the directions of lattice constants are studied on the basis of band to band transitions. We found the isotropic nature of the optical properties. Reflectivity stays low up to 1.6 eV, consistent with the energy gaps obtained using the TB-mBJ scheme in both the compounds. The refractive index, n(ω), and the extinction coefficient, k(ω), are also studied by the PBE and the TB-mBJ schemes.
ISSN:0884-2914
2044-5326
DOI:10.1557/jmr.2017.159