Superfluid density of the s-wave state for the iron-based superconductorsYunkyu Bang
Department of Physics, Chonnam National University - Kwangju 500-757, Korea and Asia Pacific Center for Theoretical Physics - Pohang 790-784, Korea
received 14 April 2009; accepted in final form 29 April 2009; published May 2009
published online 26 May 2009
We study the superfluid density of the s-wave state of the minimal two-band model for the Fe-based superconductors and its evolution with impurity concentration. We show that the impurity scattering of the strong-coupling limit induces the self-energy of a generic form beyond a critical impurity concentration . This form of causes the temperature dependence of the superfluid density . Combined with the full gap behavior of for lower impurity concentration , the s-wave state produces a continuous evolution of : exponentially flat with increasing impurity concentration that is consistent with the measurements of the Fe pnictide superconductors such as M-1111 (M = La, Nd, Sm, Pr) and Ba-122 with various dopings, except LaFePO which shows at low temperatures by a recent experiment. Our results also demonstrate that the density of states (DOS) measured by thermodynamic properties and the DOS measured by transport properties can in general be different.
74.20.-z - Theories and models of superconducting state.
74.20.Rp - Pairing symmetries (other than s-wave).
74.25.Nf - Response to electromagnetic fields (nuclear magnetic resonance, surface impedance, etc.).
© EPLA 2009