Optical Conductivity and Hall Coefficient in High-T_c Superconductors : Significant Role of Current Vertex Corrections(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

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We study AC conductivities in high-T_c cuprates, which offer us significant information to determine the true ground states. We take the current vertex correction (CVC) into account correctly to satisfy the conservation laws in terms of the fluctuation-exchange (FLEX) approximation. The significant role of the CVC on the optical Hall conductivity [σ_<xy>(ω)] is confirmed in the presence of strong antiferromagnetic (AF) fluctuations. This fact leads to the failure of the relaxation time approximation (RTA). As a result, experimental highly unusual behaviors, (i) prominent ω and temperature dependences of the optical Hall conductivity and the optical Hall coefficient [R_H(ω)], and (ii) a simple Drude form of the optical Hall angle [θ_H(ω)] for a wide range of ω, are satisfactorily reproduced. In conclusion, both DC and AC transport phenomena in (slightly under-doped) high-T_c cuprates can be explained comprehensively in terms of a nearly AF Fermi liquid, without assuming an exotic ground state.
社団法人日本物理学会の論文
2006-01-15