Muon-spin rotation measurements of the magnetic penetration depth in the Fe-based superconductor Ba(1-x)Rb(x)Fe2As2
Abstract
Measurements of the magnetic penetration depth (lambda) in the Fe-based superconductor Ba(1-x)RbxFe2As2 (x=0.3, 0.35, 0.4) were carried out using the muon-spin rotation muSR technique. The temperature dependence of lambda is well described by a two-gap s+s-wave scenario with a small gap Delta1 = 1 - 3 mev and a large gap Delta2 = 7 - 9 mev. By combining the present data with those obtained for RbFe2As2 a decrease of the BCS ratio 2Delta2/(kB)(Tc) with increasing Rb content x is observed. On the other hand, the BCS ratio 2Delta1/(kB)(Tc) is almost independent of x. In addition, the contribution of Delta1 to the superfluid density is found to increase with x. These results are discussed in the light of the suppression of interband processes upon hole doping.