Physical Review Letters
We report an infrared optical study of the pnictide high-temperature superconductor BaFe1.84Co0.16As2 and its parent compound BaFe2As2. We demonstrate that electronic correlations are moderately strong and do not change across the spin-density wave transition or with doping. By examining the energy scale and direction of spectral weight transfer, we argue that Hund's coupling J is the primary mechanism that gives rise to correlations.
Schafgans, A. A., Moon, S. J., Pursley, B. C., LaForge, A. D., Qazilbash, M. M., Sefat, A. S., ... & Basov, D. N. (2012). Electronic correlations and unconventional spectral weight transfer in the high-temperature pnictide BaFe 2− x Co x As 2 superconductor using infrared spectroscopy. Physical review letters, 108(14), 147002.