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Interfacial mode coupling as the origin of Tc enhancement in FeSe films on SrTiO3

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Illustration of single layer of superconducting FeS (ball-and-stick) atop STO (blue pyramids). When natural vibrations (green glow) from STO move into FeS film, electrons in film (white spheres) pair up and superconduct at high temperatures.

Scientific Achievement
Collaboration between LBNL and SLAC explained why a thin layer of iron selenide (FeSe) superconducts at much higher temperatures when placed atop SrTiO3 (STO) substrate.

Significance and Impact
This new understanding leads to the possibility of developing superconductors that operate at room temperature.

Research Details

  • Investigated high superconducting temperature Tc of single layer FeS placed atop SrTiO3 substrate
  • Used angle-resolved photoemission spectroscopy to measure energies of electrons ejected from sample subjected to x-rays
  • Showed that natural vibrations in SrTiO3 travel up into FeSe film in distinct packets
  • These vibrations give electrons sufficient energy to pair up and superconduct at higher Tc than they would on their own
  • Further increase of Tc may be possible by fabricating a crystal with periodic interface between FeSe and SrTiO3

J Lee, F Schmitt, R Moore, S Johnston, Y-T Cui, W Li, M Yi, Z Liu, M Hashimoto, Y Zhang, D Lu, T Devereaux, D-H Lee, Z-X Shen. Nature 515 (Nov 2014)