Systematics of c-axis phonons in the thallium- and bismuth-based cuprate superconductors

Article

关键词: BI2SR2CACU2O8+X SINGLE-CRYSTALS;    HIGH-TEMPERATURE SUPERCONDUCTOR;    INTRINSIC JOSEPHSON-JUNCTIONS;    ELECTRONIC RAMAN-SCATTERING;    TL2BA2CUO6+DELTA THIN-FILMS;    INFRARED-ACTIVE MODES;    SUBGAP STRUCTURES;    LATTICE-DYNAMICS;    OPTICAL PHONONS;    SOLUTION-MELT;   

DOI  :  10.1103/PhysRevB.60.13196

来源: SCIE

【 摘 要 】

We present grazing incidence reflectivity measurements in the far-infrared region at temperatures above and below T-c for a series of thallium- (Tl2Ba2CuO6, Tl2Ba2CaCu2O8) and bismuth- (Bi2Sr2CuO6, Bi2Sr2CaCu2O8, and Bi2-xPbxSr2CaCu2O8) based cuprate superconductors. From the spectra, which are dominated by the c-axis phonons, longitudinal optical (LO) frequencies are directly obtained. The reflectivity curves are well fitted by a series of Lorentz oscillators. In this way the transverse optical (TO) phonon frequencies were accurately determined. On the basis of the comparative study of the Bi- and Tl-based cuprates with a different number of CuO2 layers per unit cell, we suggest modifications of the assignment of the main oxygen modes. We compare the LO frequencies in Bi2Sr2CaCu2O8 and Tl2Ba2Ca2Cu3O10 obtained from intrinsic Josephson junction characteristics with our measurements, and explain the discrepancy in LO frequencies obtained by the two different methods. [S0163-1829(99)01938-3].

【 授权许可】

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