Infrared conductivity of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">Na</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mi mathvariant="normal">Co</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>: Evidence of gapped states

Hwang, Jungseek; Yang, Jerry Zhijian; Timusk, T.; Chou, F. C.

doi:10.1103/physrevb.72.024549

Cited by 52 publications

(52 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The same effect was also suggested in earlier optical study on Na 0.75 CoO 2 by Hwang et al 7 . From the analysis of the real and imaginary parts of the optical scattering rate (or the optical self-energy), they extracted an underlying bosonic mode with frequency near 600 cm −1 .…”

Section: 21222324supporting

confidence: 86%

“…The result is in good agreement with earlier studies on limited doping levels. 7,8 Obviously, the compound with high Na content has low conducting carrier density. Since the x=1 compound has a t 6 2g e 0 g (low spin state of Co 3+ ) electron configuration and is expected to be a band insulator with completely filled t 2g band and empty e g band, the gradually vanishing spectral weight for high Na content samples confirms such a band insulator for x=1 compound.…”

Section: 8mentioning

confidence: 99%

See 1 more Smart Citation

Electron-boson mode coupling and the pseudogap ofNaxCoO2by infrared spectroscopy

Luo

Wang

2006

Phys. Rev. B

View full text Add to dashboard Cite

We report the in-plane optical measurements on NaxCoO2 with 0.18≤x≤0.92. The crystal growth and characterization were described in detail. The spectral weight increases monotonically with decreasing x. For sample with the lowest Na content x∼0.18, the optical conductivity was strongly suppressed below 2200 cm −1 at low temperature. The suppression becomes weaker with increasing Na content, and disappears in charge-ordered sample with x∼0.5. At higher Na contents, similar suppression appears again but locates at higher energy scale near 3300 cm −1 . Our analysis indicates that those spectral features are dominated by a combination of electrons coupling to a bosonic mode and a pseudogap-like phenomenon. We suggest that the pseudogap-like phenomenon is purely a band structure effect. The infrared activated phonon modes were discussed in relation with the structural geometries.

show abstract

Section: 21222324supporting

confidence: 86%

Section: 8mentioning

confidence: 99%

Electron-boson mode coupling and the pseudogap ofNaxCoO2by infrared spectroscopy

Luo

Wang

2006

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…It has indeed previously been noted that the range of x = 1/2 separates two metallic regions with high conductivity for x < 0.5 and x > 0.5 [2,3]. Notably, a correspondingly rapid variation in the FIR electronic response was not observed in previous optical measurements on single crystals [11,12]. This suggests that the films can offer significant advantages concerning the homogeneity (in particular concerning the Na content) and the surface quality that is critical for optical measurements.…”

mentioning

confidence: 71%

Superconductivity in epitaxial thin films of NaxCoO2∙yD2O

Krockenberger

Fritsch

Christiani

et al. 2006

Applied Physics Letters

View full text Add to dashboard Cite

The observation of superconductivity in the layered transition metal oxide NaxCoO2∙yH2O [K. Takada et al., Nature (London) 422, 53 (2003)] has caused a tremendous upsurge of scientific interest due to its similarities and its differences to the copper based high-temperature superconductors. Two years after the discovery, we report the fabrication of single-phase superconducting epitaxial thin films of Na0.3CoO2∙1.3D2O grown by pulsed laser deposition technique. This opens additional roads for experimental research exploring the superconducting state and the phase diagram of this unconventional material.

show abstract

“…Finally, as discussed before, if the impurity parameter η is increased, the conductivity is broadened and the effect on the peak seen in the scattering rate is for it to be broadened and reduced. Recently a peak in τ −1 op (ω) in the region of 400 to 3500 cm −1 has been observed in the cobaltates 28 . This peak reduces and eventually vanishes with increasing temperature.…”

Section: A γ(ω) = ηmentioning

confidence: 96%

Optical response for thed-density-wave model

2005

View full text Add to dashboard Cite

We have calculated the optical conductivity and the Raman response for the d-density wave model, proposed as a possible explanation for the pseudogap seen in high Tc cuprates. The total optical spectral weight remains approximately constant on opening of the pseudogap at fixed temperature. This occurs because there is a transfer of weight from the Drude peak to interband transitions across the pseudogap. The interband peak in the optical conductivity is prominent but becomes progressively reduced with increasing temperature, with impurity scattering, which distributes it over a larger energy range, and with inelastic scattering which can also shift its position, making it difficult to have a direct determination of the value of the pseudogap. Corresponding structure is seen in the optical scattering rate, but not necessarily at the same energies as in the conductivity.

show abstract

Infrared conductivity ofNaxCoO2: Evidence of gapped states

Abstract: We present infrared ab-plane conductivity data for the layered cobaltate Na cm −1 and 800 cm −1 , respectively. We propose that the two gapped states of the two higher hole doped samples (x=0.50 and 0.25) are pinned charge ordered states.

Cited by 52 publications

References 32 publications

Electron-boson mode coupling and the pseudogap ofNaxCoO2by infrared spectroscopy

Electron-boson mode coupling and the pseudogap ofNaxCoO2by infrared spectroscopy

Superconductivity in epitaxial thin films of NaxCoO2∙yD2O

Optical response for thed-density-wave model

Contact Info

Product

Resources

About