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Enhanced superconductivity accompanying a Lifshitz transition in electron-doped FeSe monolayer
- Source :
- Nature Communications 8, 14988 (2017)
- Publication Year :
- 2016
-
Abstract
- The origin of enhanced superconductivity over 50 K in the recently discovered FeSe monolayer films grown on SrTiO$_{3}$ (STO), as compared to 8 K in bulk FeSe, is intensely debated. As with the ferrochalcogenides A$_{x}$Fe$_{2-y}$Se$_{2}$ and potassium doped FeSe, which also have a relatively high superconducting critical temperature ($T_c$), the Fermi surface (FS) of the FeSe/STO monolayer films is free of hole-like FS, suggesting that a Lifshitz transition by which these hole FSs vanish may help increasing $T_c$. However, the fundamental reasons explaining this increase of $T_c$ remain unclear. Here we report a 15 K jump of $T_c$ accompanying a second Lifshitz transition, characterized by the emergence of an electron pocket at the Brillouin zone (BZ) centre, that is triggered by high electron doping following in-situ deposition of potassium on FeSe/STO monolayer films. Our results suggest that the pairing interactions are orbital-dependent with the $d_{xy}$ orbital playing a determining role in generating enhanced superconductivity in FeSe.<br />Comment: 20 pages, 8 figures
Details
- Database :
- arXiv
- Journal :
- Nature Communications 8, 14988 (2017)
- Publication Type :
- Report
- Accession number :
- edsarx.1606.01470
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1038/ncomms14988