Variation in Electronic State of Ba(Fe_1−xCo_x)₂As₂ Alloy as Investigated in Terms of Transport Properties

抄録

We investigate the in-plane transport properties of the electron-doped iron arsenide superconductor Ba(Fe_1−xCo_x)₂As₂ (0≤x≤1). We observe a non-Fermi-liquid behavior characterized by an incoherent resistivity and a low-temperature increase in Hall coefficient (R_H) at x≤0.14. We discuss this feature in terms of antiferromagnetic fluctuations. We find that the effective carrier density per Fe/Co atom n_eff=−V⁄(eR_H) (V is the volume per Fe/Co atom and e is the elementary electric charge) at 250 K exhibits a nonmonotonic x dependence with a minimum value at x∼0.1, which is considered to reflect the disappearance of hole Fermi surfaces. We discuss the interrelationships among superconductivity, magnetism, and band nesting.