Electronic properties of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>3</mml:mn><mml:mi>R</mml:mi><mml:msub><mml:mrow><mml:mtext>-CuAlO</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>under pressure: Three theoretical approaches

Christensen, N. E.; Svane, A.; Laskowski, Robert; Palanivel, B.; Modak, P.; Chantis, A. N.; Schilfgaarde, Mark van; Kotani, Takao

doi:10.1103/physrevb.81.045203

Cited by 38 publications

(27 citation statements)

References 43 publications

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“…From the theoretical side, Laskowski et al 25 and Christensen et al 26 showed that absorption at the direct edge of copper delafossites is dominated by huge excitonic effects ͑about 0.5 eV͒. Similar excitonic effects were also found in experiments for CuScO 2 .…”

Section: Introductionmentioning

confidence: 57%

“…[22][23][24] Recently, Christensen et al obtained comparable calculations for CuAlO 2 under pressure using another restricted self-consistent GW scheme. 26 Finally, we should note that most experiments rely on optical absorption or transmission, with measurements of the optical band gap. This is the lowest energy we need to furnish to the system to create an electron-hole pair, and includes the electron-hole ͑excitonic͒ contribution.…”

Section: Introductionmentioning

confidence: 99%

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Band structures of delafossite transparent conductive oxides from a self-consistentGWapproach

et al. 2010

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We present a comparative study of the electronic band structures of the compounds CuMO 2 ͑M =B,Al,In,Ga͒ which belong to the family of delafossite transparent conductive oxides. The theoretical approaches we use are the standard local-density approximation ͑LDA͒ to density-functional theory, LDA + U, hybrid functionals, and perturbative GW on top of LDA or self-consistent Coulomb hole plus screened exchange calculations. The latter approach, state-of-the-art theoretical approach for quasiparticle band structures, predicts direct band gaps that are compatible with experimental optical gaps only after including the strong polaronic and excitonic effects present in these materials. For what concerns the so-called band-gap anomaly of delafossite compounds, we find that GW approaches yield the same qualitative trends with increasing anion atomic number as the LDA: accounting for the oscillator strength at the absorption edge is the key to explain the experimental trend. None of the methods that we applied beyond the simple LDA is in agreement with the small indirect gaps found by many early experiments. This supports the recent view that the absorption bands identified as a sign of the indirect experimental gaps are likely due to defect states in the gap and are not a property of the pristine material.

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Section: Introductionmentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Band structures of delafossite transparent conductive oxides from a self-consistentGWapproach

et al. 2010

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“…The optimized lattice parameter and the atomic positions show that these compounds adopt the cubic symmetry with space group Fm-3m. To verify the above result the tolerance factor (T f ) for these compounds is calculated using the formula Owing to the cubic symmetry, the equilibrium lattice constant of these perovskite is determined by the minimization of the total energy of the system with respect to the volume M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 7 of the unit cell as similar to our earlier works [19][20][21]. The calculated total energies are fitted with Brich -Murnaghan equation of state [22] to estimate the equilibrium lattice constant.…”

Section: Structural Phase Stabilitymentioning

confidence: 99%

Electronic structure, structural phase stability, optical and thermoelectric properties of Sr2AlM'O6 (M' = Nb and Ta) from first principle calculations

Rameshe

Rajagopalan

Palanivel

2015

Computational Condensed Matter

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Please cite this article as: B. Rameshe, M. Rajagopalan, B. Palanivel, Electronic structure, structural phase stability, optical and thermoelectric properties of Sr 2 AlM'O 6 (M'=Nb and Ta) from first principle calculations, Computational Condensed Matter (2015), Abstract First principle calculations are performed to investigate the electronic structure, structural phase stability, optical properties and thermoelectric properties of double perovskite oxide semiconductors namely Sr 2 AlM'O 6 (M'= Nb and Ta) in the cubic symmetry using WIEN2k. In order to study the ground state properties of these compounds, the total energies are calculated as a function of reduced volumes and fitted with Brich Murnaghan equation. The estimated ground state parameters are comparable with the available experimental data. Calculations of electronic band structure on these compounds have been carried out using generalized gradient approximations and modified Becke-Johanson potential (TB-mBJ). The calculated band gap for Sr 2 AlNbO 6 and Sr 2 AlTaO 6 with GGA and TB-mBJ reveal that these compounds exhibit semiconducting behavior with a direct band gap. To explore the optical transitions in these compounds, the real and imaginary parts of the dielectric function, refractive index, extinction coefficient, reflectivity, optical absorption coefficient, real part of optical conductivity and the energy-loss function are calculated at ambient conditions and analyzed both with GGA and TB-mBJ potentials. Investigations of the thermoelectric properties of these compounds have been carried out by the calculations of transport coefficients based on Boltzmann transport theory in order to analyze the variation of Seebeck's coefficient at different temperatures for various carrier concentrations based on the electronic structure near the valence band maxima.

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“…However, great interest in the high-pressure phases of this compound has been motivated [26][27][28][29][30] not only to clarify its phase diagram but also to learn about the evaluation of the delafossite-type AMO 2 oxides at high pressure. There is a reversible phase transition of 3R-CuAlO 2 at 34 ± 2 GPa by means of Raman scattering [26], but the density functional perturbation theory (DFPT)-LDA calculation shows the dynamical instability of 3R-CuAlO 2 at 45 GPa [28] due to the anharmonic effects when soft modes are presented.…”

Section: Introductionmentioning

confidence: 99%