Calculation of Optical Conductivity of YbB<sub>12</sub>using Realistic Tight-binding Model

Saso, Tetsuro

doi:10.1143/jpsj.73.2894

Cited by 17 publications

(13 citation statements)

References 27 publications

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“…This approach was taken because retaining only the direct gaps in the realistic band structure of YbB 12 gave an energy gap in ð!Þ much larger than the observed one. 15) We propose that the combination of phonon-assisted indirect transitions with the direct gaps in the band structure may actually improve the agreement with the experiment.…”

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confidence: 63%

“…13,14) Recently, a theory of a Tdependent energy gap in YbB 12 using realistic band structures has been reported. 15) Previously, we reported an optical study of YbB 12 single crystals. 16) The optical conductivity spectrum ð!Þ of YbB 12 clearly showed an energy gap formation below 80 K. The gap development involved a progressive depletion of ð!Þ below a shoulder at $40 meV, from which the gap magnitude was estimated to be 25 meV.…”

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confidence: 99%

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Indirect and Direct Energy Gaps in Kondo Semiconductor YbB₁₂

et al. 2005

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The optical conductivity [ð!Þ] of the Kondo semiconductor YbB 12 has been measured over wide ranges of temperature (T ¼ 8{690 K) and photon energy (h ! ! 1:3 meV). The ð!Þ data reveal the entire crossover of YbB 12 from a metallic electronic structure at high T's to a semiconducting one at low T's. Associated with the gap development in ð!Þ, a clear onset is newly found at h ! ¼ 15 meV for T 20 K. The onset energy is identified as the gap magnitude of YbB 12 appearing in ð!Þ. This gap in ð!Þ is interpreted as the indirect gap, which has been predicted by the renormalized-band model of the Kondo semiconductor. On the other hand, the strong mid-infrared (mIR) peak observed in ð!Þ is interpreted as arising from the direct gap. The absorption coefficient around the onset and the mIR peak indeed show the characteristic energy dependences expected for indirect and direct optical transitions in conventional semiconductors.

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Indirect and Direct Energy Gaps in Kondo Semiconductor YbB₁₂

et al. 2005

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“…Filling of the pseudo-gap will become faster than that of the non-interacting case since the DOS also depends on temperature. 11…”

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Absence of Hybridization Gap in Heavy Electron Systems and Analysis of YbAl₃in Terms of Nearly Free Electron Conduction Band

2007

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In the analysis of the heavy electron systems, theoretical models with c-f hybridization gap are often used. We point out that such a gap does not exist and the simple picture with the hybridization gap is misleading in the metallic systems, and present a correct picture by explicitly constructing an effective band model of YbAl3. Hamiltonian consists of a nearly free electron model for conduction bands which hybridize with localized f-electrons, and includes only a few parameters. Density of states, Sommerfeld coefficient, f-electron number and optical conductivity are calculated and compared with the band calculations and the experiments.

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“…9 Another explanation based on band structure has been proposed; i.e., that mid-IR peaks originate from a characteristic band structure in which the 4f state is located near E F . 10,11,12 In particular, both the energy position and spectral shape of the mid-IR peaks of CeX 3 (X = Pd, Sn, In) compounds can be explained by first-principle band structure calculation with the spin-orbit splitting (SOS). 12 In Yb compounds, especially YbAl 3 , however, the experimental σ(ω) spectra can be explained by band calculation in which the 4f state is slightly shifted toward E F .…”

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Origin of infrared peaks in the optical conductivity of ytterbium compounds

Kimura

2009

Phys. Rev. B

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͒ based on the direct interband transition derived from first-principle band calculation and compared the results with the experimentally obtained ͑͒ spectra. The spectral feature of a peak in the middle-infrared ͑IR͒ region ͑mid-IR peak͒ and a shoulder structure in the far-infrared region ͑far-IR shoulder͒ in the experimental ͑͒ spectra can be described by the band calculation with a common renormalization factor. This result indicates that the infrared spectra of Yb compounds originate from the interband transition from the Yb 4f state but that the Yb 4f state shifts to the Fermi level with strong electron correlation.

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Calculation of Optical Conductivity of YbB₁₂using Realistic Tight-binding Model

Cited by 17 publications

References 27 publications

Indirect and Direct Energy Gaps in Kondo Semiconductor YbB₁₂

Indirect and Direct Energy Gaps in Kondo Semiconductor YbB₁₂

Absence of Hybridization Gap in Heavy Electron Systems and Analysis of YbAl₃in Terms of Nearly Free Electron Conduction Band

Origin of infrared peaks in the optical conductivity of ytterbium compounds

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Calculation of Optical Conductivity of YbB12using Realistic Tight-binding Model

Cited by 17 publications

References 27 publications

Indirect and Direct Energy Gaps in Kondo Semiconductor YbB12

Indirect and Direct Energy Gaps in Kondo Semiconductor YbB12

Absence of Hybridization Gap in Heavy Electron Systems and Analysis of YbAl3in Terms of Nearly Free Electron Conduction Band

Origin of infrared peaks in the optical conductivity of ytterbium compounds

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Calculation of Optical Conductivity of YbB₁₂using Realistic Tight-binding Model

Indirect and Direct Energy Gaps in Kondo Semiconductor YbB₁₂

Indirect and Direct Energy Gaps in Kondo Semiconductor YbB₁₂

Absence of Hybridization Gap in Heavy Electron Systems and Analysis of YbAl₃in Terms of Nearly Free Electron Conduction Band