TRANSPORT AND STRUCTURAL STUDY OF TL2BA2CUO6+DELTA SINGLE-CRYSTALS PREPARED BY THE KCL FLUX METHOD

Tl2Ba2CuO6+delta single crystals are prepared by a KCl flux method. Transport properties and crystal structures are investigated for the samples with various T(c)'s. The result of structural analysis indicates that the change of T(c) is caused by the overdoping of the hole carrier through excess oxygen located between double Tl-O sheets. The out-of-plane resistivity rho(c) is larger than for YBa2Cu3O7, but smaller than for Bi2Sr2CaCu2O8. Temperature dependences of rho(c) are metallic for both overdoped nonsuperconducting and 75-K superconducting samples. The temperature dependence of in-plane resistivity rho(ab) changes from approximately T2 to approximately T1 with increasing T(c). The Hall coefficient R(H) exhibits a characteristic maximum at about 100 K for all samples. However, inverse Hall mobility mu(H)-1(=rho/R(H))) always shows clear T2 dependence regardless of the T(c) values, which suggests that the scattering rate of this material has approximately T2 dependence, just as in an ordinary Fermi liquid, and that the carrier concentration actually changes like that observed in n(H)(=1/R(H)e).