Publication Details

Liu, X., Liu, D., Zhang, W., He, J., Zhao, L., He, S., Mou, D., Li, F., Tang, C., Li, Z., Wang, L., Peng, Y., Liu, Y., Chen, C., Liu, G., Dong, X., Zhang, J., Chen, C., Xu, Z., Chen, X., Ma, X., Xue, Q. & Zhou, X. J. (2014). Dichotomy of the electronic structure and superconductivity between single-layer and double-layer FeSe/SrTiO3 films. Nature Communications, 5 5047-1-5047-10.


The latest discovery of possible high-temperature superconductivity in the single-layer FeSe film grown on a SrTiO3 substrate has generated much attention. Initial work found that, while the single-layer FeSe/SrTiO3 film exhibits a clear signature of superconductivity, the double-layer film shows an insulating behaviour. Such a marked layer-dependent difference is surprising and the underlying origin remains unclear. Here we report a comparative angleresolved photoemission study between the single-layer and double-layer FeSe/SrTiO3 films annealed in vacuum. We find that, different from the single-layer FeSe/SrTiO3 film, the double-layer FeSe/SrTiO3 film is hard to get doped and remains in the semiconducting/ insulating state under an extensive annealing condition. Such a behaviour originates from the much reduced doping efficiency in the bottom FeSe layer of the double-layer FeSe/SrTiO3 film from the FeSe–SrTiO3 interface. These observations provide key insights in understanding the doping mechanism and the origin of superconductivity in the FeSe/SrTiO3 films.



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