Highlights 2015
Origin of the resistive anisotropy in the electronic nematic phase of BaFe2As2 revealed by optical spectroscopy
Our optical investigation of a representative parent compound of the iron-pnictide superconductors reveals that in the paramagnetic tetragonal phase the induced dc resistivity anisotropy of strained samples is almost exclusively due to stress-induced changes in the Drude spectral weight rather than in the scattering rate. Even though impurity scattering can affect the transport anisotropy in subtle ways, it seems to have at best only limited relevance in the electronic nematic phase (a state with broken discrete rotational symmetry but unaltered translational one). This result definitively establishes the anisotropy of the Fermi surface parameters as the primary effect driving the dc transport properties in the electronic nematic state of this material.