Measurement of the thermopower anisotropy in iron arsenide

We investigated the in-plane anisotropy of the thermopower and electrical resistivity on detwinned single crystals of BaFe2As2. The in-plane anisotropy of the resistivity was clearly observed far above the magnetostructural transition temperature TAFO. While, the thermopower showed the in-plane anisotropy only below TAFO. These results are associated with the different origin of the anisotropy above and below TAFO. Since the thermopower does not depend on the scattering time, the anisotropy of the resistivity above TAFO is considered to be due to the anisotropic scattering. On the other hand, the anisotropy in the thermopower below TAFO is ascribed to the reconstructed Fermi surface.