Effect of Non-magnetic Impurities on Iron-based Superconductors

The effect of non-magnetic impurities on the normal to superconductor transition on iron-based superconductors is examined within Ginzburg-Landau phenomenological theory. The presence of such impurities depress the superconducting transition temperature. We show how the non-magnetic impurities change the order of the superconducting transition. The impurities dependence of the coherence length, penetration depth, and the critical current in superconducting thin films are calculated. It was observed from the theoretical calculations that the transition can crosses over from second to first order at the tricritical point when the concentration of the impurities change in the system.