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arXiv · 2103.08865

Positive and negative chemical pressure effects investigated in electron-doped FeSe films with an electric-double-layer structure

N. Shikama·Y. Sakishita·F. Nabeshima·A. Maeda
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Abstract

We investigated chemical pressure effects in electron-doped (e-doped) FeSe by fabricating an electric-double-layer structure with single crystalline FeSe films on LaAlO$_3$ with Se substituted by isovalent Te and S. Our method enables transport measurements of e-doped FeSe. Electron doping by applying gate voltage of 5 V increases $T_{\mathrm c}$ of the FeSe$_{1-x}$Te$_x$ and FeSe$_{1-y}$S$_y$ films with $0 \leq x \leq 0.4$ and $0 \leq y \leq 0.25$, while the e-doped $x=0.5$ film showed lower $T_{\mathrm c}$ than that of the undoped one. Both positive and chemical pressure suppress $T_{\mathrm c}$ of the e-doped FeSe. The obtained superconducting phase diagram in the e-doped samples is rather different from that in undoped samples. This might suggest that the superconductivity mechanism is different between undoped and e-doped systems. Alternatively, this is possibly explained by the absence of the nematic order in e-doped samples.

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N. Shikama, Y. Sakishita, F. Nabeshima, A. Maeda. 2021-03-16. Positive and negative chemical pressure effects investigated in electron-doped FeSe films with an electric-double-layer structure. https://doi.org/10.1103/physrevb.104.094512

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