Rationalizing doping and electronic correlations in LaFe2As2

We compute the electronic properties of the normal state of uncollapsed LaFe2As2, taking into account local dynamical correlations by means of slave-spin mean-field+density-functional theory. Assuming the same local interaction strength used to model the whole electron- and hole-doped BaFe2As2 family, our calculations reproduce the experimental Sommerfeld specific heat coefficient, which is twice the value predicted by uncorrelated band theory. We find that LaFe2As2 has a reduced bare bandwidth and this solves the apparent paradox of its sizeable correlations despite its nominal valence d6.5, which would imply extreme overdoping and uncorrelated behaviour in BaFe2As2. Our results yield a consistent picture of the whole 122 family and point at the importance of the correlation strength, rather than sheer doping, in the interpretation of the phase diagram of iron-based superconductors.