Infrared optical properties of Pr2CuO4

Article

关键词: CRYSTAL-FIELD EXCITATIONS;    SPIN-PHONON INTERACTION;    TRANSPORT-PROPERTIES;    SINGLE-CRYSTALS;    ND2CUO4;    SPECTROSCOPY;    CU;    SUPERCONDUCTIVITY;    ND1.85CE0.15CUO4;    CONDUCTIVITY;   

DOI  :  10.1103/PhysRevB.66.144511

来源: SCIE

【 摘 要 】

The a-b-plane reflectance of a Pr2CuO4 single crystal has been measured over a wide frequency range at a variety of temperatures, and the optical properties determined from a Kramers-Kronig analysis. Above approximate to250 K, the low-frequency conductivity increases quickly with temperature; rho(dc)approximate to1/sigma(1)(omega-->0) follows the form rho(dc)proportional toexp(E-a/k(B)T), where E(a)approximate to0.17 eV is much less than the inferred optical gap of approximate to1.2 eV. Transport measurements show that at low temperature the resistivity deviates from activated behavior and follows the form rho(dc)proportional toexp[(T-0/T)(1/4)], indicating that the dc transport in this material is due to variable-range hopping between localized states in the gap. The four infrared-active E-u modes dominate the infrared optical properties. Below approximate to200 K, a striking new feature appears near the low-frequency E-u mode, and there is an additional new fine structure at high frequency. A normal coordinate analysis has been performed and the detailed nature of the zone-center vibrations determined. Only the low-frequency E-u mode has a significant Pr-Cu interaction. Several possible mechanisms related to the antiferromagnetism in this material are proposed to explain the sudden appearance of this and other new spectral features at low temperature.

【 授权许可】

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