We investigated the out-of-plane transport properties of parent and chemically substituted ${\mathrm{BaFe}}_2{\mathrm{As}}_2$ for various types of substitution. Based on the studies of the Hall coefficient and chemical-substitution effect, we have clarified the origin for the unusual temperature dependence of out-of-plane resistivity ${\rho }_c\left(T\right)$ in the high-temperature paramagnetic-tetragonal phase. Electron (hole) carriers have an incoherent (coherent) character, which is responsible for nonmetallic (metallic) ${\rho }_c\left(T\right)$. Although the electron and hole contributions are almost comparable, a slightly larger contribution comes from electrons at high temperatures but from holes at low temperatures, resulting in a maximum in ${\rho }_c\left(T\right)$. In the low-temperature antiferromagnetic-orthorhombic phase, the major effect of substitution is to increase the residual-resistivity component, as in the case for the in-plane transport. In particular, Co atoms substituted for Fe give rise to strong scattering with large ac anisotropy. We found that K substitution induces a nonmetallic behavior in ${\rho }_c\left(T\right)$ at low temperatures, which is likely due to a weakly localized nature along the $c$-axis direction.

中文翻译：

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BaFe2As2中平面外输运性质的综合研究：三维电子状态和化学取代的影响

我们研究了母体和化学取代的母体的平面外传输特性 ${\mathrm{钡铁}}_{\mathrm{2个}}{\mathrm{作为}}_{\mathrm{2个}}$用于各种类型的替换。基于霍尔系数和化学取代效应的研究，我们澄清了面外电阻率异常温度依赖性的起因${\rho }_C（Ť）$在高温顺磁性-四方相中。电子（空穴）载流子具有非相干（相干）特性，这是造成非金属（金属）载流子的原因${\rho }_C（Ť）$。尽管电子和空穴的贡献几乎是可比的，但稍高的贡献来自高温的电子，而来自低温的空穴，从而导致最大的${\rho }_C（Ť）$。在低温反铁磁-斜方晶相中，取代的主要作用是与平面内传输一样，增加残余电阻率分量。特别是，取代Fe的Co原子引起交流各向异性大的强散射。我们发现，K取代会在${\rho }_C（Ť）$ 在低温下，这很可能是由于沿着 $C$轴方向。