Distribution of Optical Spectral Weight in Detwinned Ba(Fe1− x Co x )2As2

We analyze our recent optical investigation on detwinned Ba(Fe1−x Co x )2As2 materials in the underdoped regime from the perspective of the spectral weight (SW) distribution. We identify its evolution for both in-plane crystallographic axes as a function of temperature across the structural tetragonal-orthorhombic phase transition. We can thus disentangle the anisotropy of SW occurring in the orthorhombic magnetic phase, from where we identify the relevant energy scales arising from interactions with spin fluctuation