Inter-plane resistivity of isovalent doped BaFe$_2$(As$_1-x$P$_x$)$_2$

Temperature-dependent inter-plane resistivity, $ρ _c(T)$, was measured for the iron-based superconductor BaFe$_2$(As$_1-x$P$_x$)$_2$ over a broad isoelectron phosphorus substitution range from $x$=0 to $x$=0.60, from non-superconducting parent compound to heavily overdoped superconducting composition with $T_c≈ 10~K$. The features due to structural and magnetic transitions are clearly resolved in $ρ _c(T)$ of the underdoped crystals. A characteristic maximum in $ρ _c(T)$, found in the parent BaFe$_2$As$_2$ at around 200~K, moves rapidly with phosphorus substitution to high temperatures. At the optimal doping, the inter-plane resistivity shows $T$-linear temperature dependence without any cross-over anomalies, similar to the previously reported in-plane resistivity. This observation is in stark contrast with dissimilar temperature dependences found at optimal doping in electron-doped Ba(Fe$_1-x$Co$_x$)$_2$As$_2$. Our finding suggests that despite similar values of the resistivity and its anisotropy, the temperature dependent transport in the normal state is very different in electron and isoelectron doped compounds. Similar temperature dependence of both in-plane and inter-plane resistivities, in which the dominant contributions are coming from different parts of the Fermi surface, suggests that scattering is the same on the whole Fermi surface. Since magnetic fluctuations are expected to be much stronger on the quasi-nested sheets, this observation may point to the importance of the inter-orbital scattering between different sheets.