Infrared properties of La2-x(Ca,Sr)(x)CaCu2O6+delta single crystals

Article

关键词: NEUTRON POWDER DIFFRACTION;    CHARGE DYNAMICS;    OPTICAL CONDUCTIVITY;    CUPRATE SUPERCONDUCTORS;    ELECTRONIC-STRUCTURE;    LA2-XSRXCUO4;    STATE;    GAP;    SPECTROSCOPY;    PSEUDOGAP;   

DOI  :  10.1103/PhysRevB.67.134526

来源: SCIE

【 摘 要 】

The in-plane optical properties of two crystals of the bilayer cuprate La2-x(Ca,Sr)(x)CaCu2O6+delta, one with excess Ca and x=0.10 and the other with Sr and x=0.15, were investigated over the frequency range of 45-25 000 cm(-1). The optical conductivity has been derived from Kramers-Kronig transformation. Each crystal exhibits a peak at around 15 000 cm(-1), which corresponds to the charge-transfer (CT) excitation 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.

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