Superconducting transition of FeSe/SrTiO3 induced by adsorption of semiconducting organic molecules

TL;DR

This study demonstrates that adsorption of semiconducting organic molecules can induce or suppress superconductivity in FeSe films on SrTiO3, highlighting the role of local electron concentration in the transition.

Contribution

It reveals how charge transfer from organic molecules modulates superconductivity in FeSe/SrTiO3, providing insights into local electronic effects on superconducting transitions.

Findings

Donor molecules induce superconductivity in non-superconducting FeSe.

Acceptor molecules suppress superconductivity in FeSe.

Electronic states and work function evolve with molecular adsorption.

Abstract

We prepared superconducting and non-superconducting FeSe films on SrTiO3(001) substrates (FeSe/STO) and investigated the superconducting transition induced by charge transfer between organic molecules and FeSe layers by low temperature scanning tunneling microscopy and spectroscopy. At low coverage, donor- and acceptor-type molecules adsorbed preferentially on the non-superconducting and superconducting FeSe layers, respectively. Superconductivity was induced by donor molecules on non-superconducting FeSe layer, while the superconductivity was suppressed near acceptor molecules. The corresponding evolutions of electronic states and work function were also resolved by scanning tunneling microscopy. These results illustrate the important role played by local electron concentration in the superconducting transition of FeSe/STO.