摘要High quality Sr14-xCaxCu24O41 single-crystals are successfully grown by floating-zone technique, and the transport properties are studied. The temperature dependence of resistivity along the c-axis direction is semiconductor-like for x≤10 and it can be fitted by the thermal activation equation ρ=ρ0exp(Δ/kBT) with k_B being the Boltzmann constant and Δ the activation energy. A break in the slope of thermopower (S) versus the inverse temperature (1/T) corresponding to the formation of charge-density waves (CDW) is first observed for x≤6. The temperature dependence of thermopower becomes metallic for x≥8 while the resistivity is still semiconductor-like. We propose that the insulation behaviour of the resistivity in the Ca doping range 8≤ x≤11 could result from the localization of the charge carriers due to the disorder induced by Ca doping and a revised electronic phase diagram is derived based on our observations.
Abstract：High quality Sr14-xCaxCu24O41 single-crystals are successfully grown by floating-zone technique, and the transport properties are studied. The temperature dependence of resistivity along the c-axis direction is semiconductor-like for x≤10 and it can be fitted by the thermal activation equation ρ=ρ0exp(Δ/kBT) with k_B being the Boltzmann constant and Δ the activation energy. A break in the slope of thermopower (S) versus the inverse temperature (1/T) corresponding to the formation of charge-density waves (CDW) is first observed for x≤6. The temperature dependence of thermopower becomes metallic for x≥8 while the resistivity is still semiconductor-like. We propose that the insulation behaviour of the resistivity in the Ca doping range 8≤ x≤11 could result from the localization of the charge carriers due to the disorder induced by Ca doping and a revised electronic phase diagram is derived based on our observations.
(Metal-insulator transitions and other electronic transitions)
引用本文:
WANG Qing-Bo;XU Xiang-Fan;TAO Qian;WANG Hong-Tao;XU Zhu-An. Metal--Insulator Transition in Ca-Doped Sr14-xCaxCu24O41 Systems Probed by Thermopower Measurements[J]. 中国物理快报, 2008, 25(5): 1857-1860.
WANG Qing-Bo, XU Xiang-Fan, TAO Qian, WANG Hong-Tao, XU Zhu-An. Metal--Insulator Transition in Ca-Doped Sr14-xCaxCu24O41 Systems Probed by Thermopower Measurements. Chin. Phys. Lett., 2008, 25(5): 1857-1860.
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2008, Vol. 25 
