Temperature-dependent anisotropic resistivity in electron, hole and isoelectron - doped BaFe$_2$As$_2$ superconductors

Anisotropic electrical resistivity, $\rho(T)$, was studied in iron-arsenide superconductors, obtained by doping the parent BaFe$_2$As$_2$ compound on three different sites: (1) electron donor transition metal (Co,Ni,Rh,Pd) substitution of Fe [1,2]; (2) hole donor K substitution of Ba [3]; (3) isoelectron P substitution of As. For all three types of dopants a range of $T$-linear behavior is found at the optimal doping in both the in-plane and the inter-plane $\rho(T)$ above $T_c$. At some higher temperature this range of $T$-linear resistivity is capped by a slope-changing anomaly, which, by comparison with NMR, magnetic susceptibility and Hall effect measurements, can be identified with the onset of carrier activation over the pseudogap [1]. The doping-evolution of anisotropic temperature dependent $\rho(T)$ and of the pseudogap are quite different for three types of doping. A three-dimensional $T-H$ phase diagram summarizing our results will be presented. Furthermore, potential correlation of the anisotropic normal state transport and anisotropic superconducting state heat transport will be discussed. \\[4pt] In collaboration with N. Ni, A. Thaler, S.L.Bud'ko, P.C. Canfield, R. Prozorov, Bing Shen, Hai-Hu Wen, K. Hashimoto, S. Kasahara, T. Terashima, T. Shibauchi and Y. Matsuda. \\[4pt] [1] M.A.Tanatar et al. PRB \textbf{82}, 134528 (2010)\\[0pt] [2] M.A.Tanatar et al. PRB \textbf{84}, 014519 (2011)\\[0pt] [3] M.A.Tanatar et al. arXiv:1106.0533