Fig. 3
From: Multi-band mass enhancement towards critical doping in a pnictide superconductor
a Doping dependence, x, of the components of the electronic specific heat divided by temperature, γ, as measured in our study of BaFe2(As1−xPx)2. As phosphorus doping approaches optimal doping (x = 0.31) from the overdoped side, the quasiparticle density of states recovered by suppression of superconductivity, γH (red circles), exhibits an enhancement by more than a factor of two over the doping range studied. The component that persists in the superconducting state in the zero-temperature, zero-magnetic field limit, γbg (blue circles), exhibits the opposite trend with doping, showing a decrease by almost a factor of three over the same range of doping. The sum of γH and γbg, (gray crosses) is also plotted and shows an increase by a factor of roughly 1.3. Error bars reflect the standard deviation. b Doping dependence of γH replotted from panel a (red circles) with the corresponding sum of the corresponding of the quasiparticle masses given on the right axis, determined as described in the text. Also plotted is the quasiparticle effective mass of the β-pocket (empty squares) reported from quantum fluctuation measurements by Walmsley et al.3 Note that γH, the sum of the quasiparticle masses over all pockets taking part in superconductivity, shows a more dramatic enhancement than is seen in the β-pocket alone
