We measured the transport properties and susceptibility of single-crystal Ca${}_{1-x}$La${}_x$Fe${}_2$As${}_2$ ($x=0$, 0.05, 0.1, 0.15, 0.19, and 0.25). Large in-plane resistivity anisotropy similar to that in Co-doped 122 iron pnictides is observed although no transition metals were introduced in the FeAs plane. The in-plane resistivity anisotropy gradually increases with La doping below $T_{\text{SDW}}$, being different from the hole-doped 122 superconductors. The susceptibilities of the samples show that La doping leads to suppression of the spin-density wave (SDW) and induces a Curie-Weiss-like behavior at low temperature, which is much stronger than the other 122 iron-based superconductors.

• Received 19 December 2011

DOI:https://doi.org/10.1103/PhysRevB.85.144514