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

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 $0\le x\le 0.4$ and $0\le y\le 0.25$, 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.

15 pages, 4 figures

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Cited by in corpus (6)

• Phase diagrams on composition-spread Fe${}_y$Te${}_{1-x}$Se${}_x$ films
• Interface superconductivity in FeSe thin films on SrTiO${}_3$grown by the PLD technique
• Anisotropy of upper critical fields and interface superconductivity in FeSe/SrTiO3 grown by PLD
• In-situ electrical and thermal transport properties of FeySe1-xTex films with ionic liquid gating
• Studies of superconductivity of Fe chalcogenides in films grown by PLD technique
• Fabrication of oxide/FeSe multilayer films using the PLD technique