Inter-chain Interaction of Metallic 1D-chain in PrBa 2 Cu 4 O 8
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Inter-chain Interaction of Metallic 1D-chain in PrBa2Cu4O8 Shigeru Horii, H. Takagi1, H. Ikuta2, U. Mizutani3, Y. Yamada4, I. Hirabayashi5, J. Shimoyama and K. Kishio Department of Superconductivity, University of Tokyo, Tokyo 113-8656, Japan 1 Department of Advanced Materials Science, University of Tokyo, Tokyo 113-0033, Japan 2 Department of Crystalline Materials Science, Nagoya University, Nagoya 464-8603, Japan 3 Center for Integrated Research in Science and Engineering, Nagoya University, Nagoya 464-8603, Japan 4 Department of Material Science, Shimane University, Matsue 690-8504, Japan 5 Superconductivity Research Laboratory, ISTEC, Nagoya 456-8587, Japan ABSTRACT The a- and b-axis resistivities and the a-axis magnetoresistivities applying magnetic field (B) along all three crystallographic axes in non-superconductive PrBa2Cu4O8 single crystals have been measured using four-probe method. Resistivitiy along the b-axis (parallel to double-chains) showed a highly conductive behavior, of which the origin is attributed to the double-chains because of a large anisotropic conduction between a- and b-axis directions. However, a metallic behavior along the a-axis was also observed in temperature region below 130 K, which could be understood in terms of presence of finite and coherent inter-chain interaction along the a-axis direction. This conclusion is derived from good agreement with values of mean-free path length in the double chain, lchain estimated from both the ρb-T curve and the a-axis MR applying B//c using quasi-one-dimensional (quasi-1D) band model.
INTRODUCTION Experimental studies on a carrier-doped 1D systems are of importance as well because a 1D metallic state is theoretically predicted to exhibit a Tomonaga-Luttinger liquid in which degrees of freedom of spin and charge are separated [1,2]. The discovery of high-temperature superconductors has stimulated many studies of strongly correlated systems in low-dimensional materials. In 1D strongly correlated electrons systems, the Cu-O chain is believed to be one of the most useful structures with respect to experimental survey of carrier-doping effects on 1D Mott insulator. Particularly, the double-chain structure in non-superconductive PrBa2Cu4O8 (Pr124) was suggested to be a possibility of self-doping of mobile carriers in a stoichiometric composition from the resistivity measurement using polycrystalline Pr124 samples [3,4,5] and YBa2Cu4O8 (Y124) single crystals[6]. Furthermore, this structure has no oxygen deficiency, and the electronic conduction of CuO2 planes in Pr124 is suppressed, for which the so-called Fehrenbacher-Rice state formed by the hybridization of Pr 4f and O 2p orbital is considered to be responsible [7]. Hence, the Pr124 is more advantageous compared with Y-Ba-Cu-O and PrBa2Cu3O7 (Pr123) in terms of localization of doped carriers by oxygen defects in chain and a certain ambiguity in probing the chain transport by presence of superconductive 2D CuO2 planes. Recently, we have successfully grown single crystals of Pr124 by means of a flu
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