Doubling of the critical temperature of FeSe observed in point contacts

A rise in the superconducting critical temperature T_c of more than two times (exceeding 20 K) is discovered in point contacts created between iron chalcogenide FeSe single crystals and Cu. The possible reasons for such a T_c increase in point contacts are discussed. The most likely cause for this may be the interfacial carrier doping and/or interfacial enhanced electron-phonon interaction.