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Dimensional crossover and anomalous magnetoresistivity in single crystals $Na_xCoO_2$

C. H. Wang·X. H. Chen·J. L. Luo·G. T. Liu·X. X. Lu·H. T. Zhang·G. Y. Wang·X. G. Luo·N. L. Wang
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Abstract

The in-plane ($ρ_{ab}$) and c-axis ($ρ_c$) resistivities, and the magnetoresistivity of single crystals $Na_xCoO_2$ with x = 0.7, 0.5 and 0.3 were studied systematically. $ρ_{ab}(T)$ shows similar temperature dependence between $Na_{0.3}CoO_2$ and $Na_{0.7}CoO_2$, while $ρ_c(T)$ is quite different. A dimensional crossover from two to three occurs with decreasing Na concentration from 0.7 to 0.3. The angular dependence of in-plane magnetoresistivity for 0.5 sample shows a \emph{"d-wave-like"} symmetry at 2K, while the \emph{"p-wave-like"} symmetry at 20 K. These results give an evidence for existence of a \emph{spin ordering orientation} below 20 K turned by external field, like the stripes in cuprates.

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C. H. Wang, X. H. Chen, J. L. Luo, G. T. Liu, X. X. Lu, H. T. Zhang, G. Y. Wang, X. G. Luo, N. L. Wang. 2004-11-02. Dimensional crossover and anomalous magnetoresistivity in single crystals $Na_xCoO_2$. https://doi.org/10.1103/physrevb.71.224515

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