Charge transport along the c-axis in high-T_c cuprates.pdf

c o n d - m a t / 9 9 1 0 3 2 0 v 2 1 0 N o v 1 9 9 9 To be published in “Advances in Superconductivity XII”, Proceedings of the 12 th International Symposium on Superconductivity (ISS ’99), October 17-19, 1999, Morioka. - 1 - Charge Transport along the c-Axis in High-Tc Cuprates * Yoichi Ando Central Research Institute of Electric Power Industry, Komae, Tokyo 201-8511, Japan Abstract: Using 61-T pulsed magnetic fields, the normal-state ρab and ρc are measured in Bi-2201 system down to 0.66 K, and the coexistence of the “metallic” ρab and the “semiconducting” ρc, usually called the charge confinement behavior, was confirmed to extend far below Tc. Recent measurement of the c-axis magnetoresistance under 16 T dc magnetic field in heavily underdoped Y-123 crystals revealed that the peculiar c-axis charge transport, and thus the charge confinement, is fundamentally related to the antiferromagnetic spin fluctuations. Keywords: anisotropy, resistivity, transport properties, normal state, magnetoresistance INTRODUCTION One of the most unusual normal-state properties of the high-Tc cuprates is the temperature dependence of the anisotropic resistivity: in samples near optimum doping, the in-plane resistivity ρab decreases linearly with decreasing T over a wide temperature range, while the out-of-plane resistivity ρc increases rapidly at low temperatures. To elucidate whether this contrasting behavior extends far below Tc and thus is truly a “ground state” property of the normal state in the absence of superconductivity, we measured the normal-state ρab and ρc in La-doped Bi2Sr2CuOy (Bi-2201) crystals by suppressing superconductivity with 61-T pulsed magnetic fields [1]. In sufficiently clean samples, we confirmed that the metallic ρab coexists with a “semiconducting” ρc down to the lowest experimental temperature, 0.66 K, giving evidence of the non-Fermi-liquid nature of the cuprates. This result also evidences the exi