To elucidate the mechanisms behind the enhanced Tc in monolayer (1ML) FeSe on SrTiO3 (STO), we grew highly strained 1ML FeSe on the rectangular (100) face of rutile TiO2, and observed the coexistence of replica bands and superconductivity with a Tc of 63 K. From the similar Tc between this system and 1ML FeSe on STO (001), we conclude that strain and dielectric constant are likely unimportant to the enhanced Tc in these systems. A systematic comparison of 1ML FeSe on TiO2 with other systems in the FeSe family shows that while charge transfer alone can enhance Tc, it is only with the addition of interfacial electron-phonon coupling that Tc can be increased to the level seen in 1ML FeSe on STO.
@article{arxiv.1606.09358,
title = {Universal Substrate Effect on the Superconductivity of FeSe Monolayer Films},
author = {Slavko Rebec and Tao Jia and Chaofan Zhang and Makoto Hashimoto and Donghui Lu and Robert Moore and Zhixun Shen},
journal= {arXiv preprint arXiv:1606.09358},
year = {2017}
}