Infrared properties of La${}_{2-x}$(Ca,Sr)${}_x$CaCu${}_2$O${}_{6+\delta }$ single crystals

Abstract

The in-plane optical properties of two crystals of the bilayer cuprate \LSxCCO, one with excess Ca and $x=0.10$ and the other with Sr and $x=0.15$, were investigated over the frequency range of 45--25000 cm${}^{-1}$. The optical conductivity has been derived from Kramers-Kronig transformation. Each crystal exhibits a peak at around 15000 cm${}^{-1}$ which corresponds to the charge-transfer gap of the parent insulator. With increasing carrier density, spectral weight shifts from the CT excitation to the low-$\omega$ region. For the superconducting sample ($x=0.15$), the optical conductivity displays a peak in the far-infrared region, which shifts toward zero frequency with decreasing temperature. The temperature-dependent behavior favors a dynamical localization picture. A ``pseudogap'' feature is observed in the low-frequency reflectance and the scattering rate spectra. Both the energy scale and the temperature dependence of the ``pseudogap'' are similar to other bilayer cuprates.

arXiv comment5 pages, 3 figures

References in corpus (7)

• Non-Fermi liquid behavior of SrRuO_3 -- evidence from infrared conductivity
• Electronic structure of the trilayer cuprate superconductor Bi${}_2$Sr${}_2$Ca${}_2$Cu${}_3$O${}_{10+\delta }$
• Infrared signatures of charge stripes in La(2-x)Sr(x)CuO(4)
• Raman Scattering versus Infrared Conductivity: Evidence for one-dimensional Conduction in La_{2-x}Sr_{x}CuO_{4}
• In-plane optical response of Bi2Sr2CuO6
• Scattering Rate Gap in the IR Response of HgBa_2Ca_2Cu_3O_{8+delta}
• Structural and Magnetic Instabilities of La${}_{2-x}$Sr${}_x$CaCu${}_2$O${}_6$

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