Effect of Li-deficiency impurities on the electron-overdoped LiFeAs   superconductor
  We use transport, inelastic neutron scattering, and angle resolved photoemission experiments to demonstrate that the stoichiometric LiFeAs is an intrinsically electron-overdoped superconductor similar to those of the electron-overdoped NaFe1-xTxAs and BaFe2-xTxAs2 (T = Co,Ni). Furthermore, we show that although transport properties of the stoichiometric superconducting LiFeAs and Li-deficient nonsuperconducting Li1-xFeAs are different, their electronic and magnetic properties are rather similar. Therefore, the nonsuperconducting Li1-xFeAs is also in the electron overdoped regime, where small Li deficiencies near the FeAs octahedra can dramatically suppress superconductivity through the impurity scattering effect. 
Meng Wang, Miaoyin Wang, Hu Miao, S.V.Carr, D.L.Abernathy, M.B.Stone,   X.C.Wang, Lingyi Xing, C.Q.Jin, Xiaotian Zhang, Jian...
cond-mat.supr-con