Superconductivity in Mg/MgO interface
  Metastable superconductivity at \approx 50 K in the interfaces formed by metallic and oxidized magnesium (MgO) has been observed by ac magnetic susceptibility and electrical resistance measurements. The superconducting interfaces have been produced by the surface oxidation of metallic magnesium under special conditions. 
N. S. Sidorov, A. V. Palnichenko, O. M. Vyaselev
cond-mat.supr-con