Suppression of high temperature superconductivity in single layer FeSe nanoribbons*

At reduced dimensions, there exists additional characteristic length scales below which superconductivity can be suppressed. The determination of those critical parameters is of fundamental importance in understanding Cooper pairing mechanisms, and the application of these materials in nanoscale superconducting devices. Here, single layer FeSe nanoribbons of well-defined widths from a few to tens of nanometers are prepared by molecular beam epitaxy on SrTiO3(001) substrates. Scanning tunneling spectroscopy reveals a superconducting gap of up to 20 meV, and a critical width of 7.2 nm below which superconductivity is suppressed. Those findings and possible mechanisms for this suppression will be discussed at the meeting.