Evidence of Mott physics in iron pnictides from x-ray spectroscopy

X-ray emission and absorption spectroscopies are jointly used as fast probes to determine the evolution as a function of doping of the fluctuating local magnetic moments in K- and Cr- hole-doped BaFe2As2. An increase in the local moment with hole-doping is found, supporting the theoretical scenario in which a Mott insulating state that would be realized for half-filled conduction bands has an influence throughout the phase diagram of these iron-pnictides.