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arXiv · 1208.3646

Anisotropic resistivity of Na$_{1-\delta}$Fe$_{1-x}$Co$_x$As

N. Spyrison·M. A. Tanatar·Kyuil Cho·Y. Song·Pengcheng Dai·Chenglin Zhang·R. Prozorov
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Abstract

Temperature-dependent resistivity is studied in single crystals of iron-arsenide superconductor Na$_{1-\delta}$Fe$_{1-x}$Co$_x$As for electrical current directions along, $\rho_a (T)$, and transverse, $\rho_c (T)$, to the Fe-As layers. Doping with Co increases stability of this compound to reaction with the environment and suppresses numerous features in both $\rho_a(T)$ and $\rho_c(T)$ compared to the stoichiometric NaFeAs. Evolution of $\rho_a (T)$ with $x$ follows a universal trend observed in other pnictide superconductors, exhibiting a $T$-linear temperature dependence close to the optimal doping and development of $T^2$ dependence upon further doping. $\rho_c (T)$ in parent compound shows a non - monotonic behavior with a crossover from non-metallic resistivity increase on cooling from room temperature down to $\sim$ 80 K to a metallic decrease below this temperature. Both $\rho_a (T)$ and $\rho_c (T)$ show several correlated crossover - like features at $T>$ 80 K. Despite a general trend towards more metallic behavior of inter - plane resistivity in Co-doped samples, the temperature of the crossover from insulating to metallic behavior (80 K) does not change much with doping.

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N. Spyrison, M. A. Tanatar, Kyuil Cho, Y. Song, Pengcheng Dai, Chenglin Zhang, R. Prozorov. 2012-08-17. Anisotropic resistivity of Na$_{1-\delta}$Fe$_{1-x}$Co$_x$As. https://doi.org/10.1103/physrevb.86.144528

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