Highlights 2014

We develop a new technique that permits in-situ variation of uniaxial stress to probe the polarization dependence of the optical reflectivity of the representative underdoped iron-arsenide Ba(Fe_1-xCo_x)₂As₂ (x ≤ 0.5%) through the tetragonal-to-orthorhombic structural transition and with respect to their electronic nematic phase. Uniaxial pressure is acting as external symmetry breaking field and allows detwinning the specimens with respect to the ferro-elastic transition. At T < T_s, we discover a remarkable hysteretic optical anisotropy as a function of the applied pressure at energies far away from the Fermi level. Such an anisotropy turns into a reversible linear pressure dependence at T ≥ T_s. Moreover, the optical anisotropy gets progressively depleted with increasing Co-content in the underdoped regime, consistent with the doping dependence of the orthorhombicity but contrary to the non-monotonic behavior observed for the dc anisotropy.

Related papers

• external pageHysteretic behavior in the optical response of the underdoped Fe-arsenide Ba(Fe1-xCox)2As2in the electronic nematic phasecall_made 
• external pageNematic-driven anisotropic electronic properties of underdoped detwinned Ba(Fe1-xCox)2As2revealed by optical spectroscopycall_made