Doubling of the critical temperature of FeSe observed in point contacts

Rise in superconducting critical temperature Tc more than two times (exceeding 20 K) is discov- ered in point-contacts created between iron-chalcogenide FeSe single crystal and Cu. The possible reasons of such Tc increase in point-contacts are discussed. The most probable cause for this may be the interfacial carriers doping and/or interfacial enhanced electron-phonon interaction.