Proximity induced superconductivity within the insulating   (Li$_{0.84}$Fe$_{0.16}$)OH layers in (Li$_{0.84}$Fe$_{0.16}$)OHFe$_{0.98}$Se
  The role played by the insulating intermediate (Li$_{0.84}$Fe$_{0.16}$)OH layer on magnetic and superconducting properties of (Li$_{0.84}$Fe$_{0.16}$)OHFe$_{0.98}$Se was studied by means of muon-spin rotation. It was found that it is not only enhances the coupling between the FeSe layers for temperatures below $\simeq 10$ K, but becomes superconducting by itself due to the proximity to the FeSe ones. Superconductivity in (Li$_{0.84}$Fe$_{0.16}$)OH layers is most probably filamentary-like and the energy gap value, depending on the order parameter symmetry, does not exceed 1-1.5 meV. 
Rustem Khasanov, Huaxue Zhou, Alex Amato, Zurab Guguchia, Elvezio   Morenzoni, Xiaoli Dong, Guangming Zhang, and Zhongxian Zhao
cond-mat.supr-con