Lowerature Charging Dynamics of the Ionic Liquid and Its Gating Effect on FeSe0.5Te0.5 Superconducting Films

Cheng Zhang; Wei Zhao; Sheng Bi; Christopher M. Rouleau; Jason D. Fowlkes; Walker L. Boldman; Genda Gu; Qiang Li; Guang Feng; Philip D. Rack

doi:10.1021/acsami.9b02373

Lowerature Charging Dynamics of the Ionic Liquid and Its Gating Effect on FeSe_0.5Te_0.5 Superconducting Films

Cheng Zhang, Wei Zhao, Sheng Bi, Christopher M. Rouleau, Jason D. Fowlkes, Walker L. Boldman, Genda Gu, Qiang Li, Guang Feng, Philip D. Rack

Functional Hybrid Nanomaterials

Research output: Contribution to journal › Article › peer-review

11 Scopus citations

Abstract

Ionic liquids (ILs) have been investigated extensively because of their unique ability to form the electric double layer (EDL), which induces high electrical field. For certain materials, lowerature IL charging is needed to limit the electrochemical etching. Here, we report our investigation of the lowerature charging dynamics in two widely used ILs-DEME-TF₂N and C₄mim-TF₂N. Results show that the formation of the EDL at â220 K requires several hours relative to milliseconds at room temperature, and an equivalent voltage V_e is introduced as a measure of the EDL formation during the biasing process. The experimental observation is supported by molecular dynamics simulation, which shows that the dynamics are logically a function of gate voltage, time, and temperature. To demonstrate the importance of understanding the charging dynamics, a 140 nm thick FeSe_0.5Te_0.5 film was biased using the DEME IL, showing a tunable T_c between 18 and 35 K. Notably, this is the first observation of the tunability of the T_c in thick film FeSe_0.5Te_0.5 superconductors.

Original language	English
Pages (from-to)	17979-17986
Number of pages	8
Journal	ACS Applied Materials and Interfaces
Volume	11
Issue number	19
DOIs	https://doi.org/10.1021/acsami.9b02373
State	Published - May 15 2019

Funding

C.Z. and P.D.R. acknowledge support by U.S. Department of Energy (DOE) under grant DE-SC0002136. W.Z., S.B., and G.F. thank support from the National Natural Science Foundation of China (51876072). C.M.R. and J.D.F. acknowledge support by the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. W.B. acknowledges support from NSF (grant #1544686). FST superconducting films were made at Brookhaven National Laboratory. Q.L. and G.G. were supported by the Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, US Department of Energy under contract no. DESC0012704. The authors also acknowledge that the device fabrication and electrical measurements were conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. G.F. also acknowledges support from Shenzhen Basic Research Project (JCYJ20170307171511292). All MD simulations were performed at the National Supercomputing Centers in Guangzhou (Tianhe II).

Keywords

2D materials
ionic liquid
iron-based superconductor
molecular dynamics simulation

Access to Document

10.1021/acsami.9b02373

Cite this

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title = "Lowerature Charging Dynamics of the Ionic Liquid and Its Gating Effect on FeSe0.5Te0.5 Superconducting Films",

abstract = "Ionic liquids (ILs) have been investigated extensively because of their unique ability to form the electric double layer (EDL), which induces high electrical field. For certain materials, lowerature IL charging is needed to limit the electrochemical etching. Here, we report our investigation of the lowerature charging dynamics in two widely used ILs-DEME-TF2N and C4mim-TF2N. Results show that the formation of the EDL at {\^a}220 K requires several hours relative to milliseconds at room temperature, and an equivalent voltage Ve is introduced as a measure of the EDL formation during the biasing process. The experimental observation is supported by molecular dynamics simulation, which shows that the dynamics are logically a function of gate voltage, time, and temperature. To demonstrate the importance of understanding the charging dynamics, a 140 nm thick FeSe0.5Te0.5 film was biased using the DEME IL, showing a tunable Tc between 18 and 35 K. Notably, this is the first observation of the tunability of the Tc in thick film FeSe0.5Te0.5 superconductors.",

keywords = "2D materials, ionic liquid, iron-based superconductor, molecular dynamics simulation",

author = "Cheng Zhang and Wei Zhao and Sheng Bi and Rouleau, {Christopher M.} and Fowlkes, {Jason D.} and Boldman, {Walker L.} and Genda Gu and Qiang Li and Guang Feng and Rack, {Philip D.}",

note = "Publisher Copyright: {\textcopyright} 2019 American Chemical Society.",

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AU - Fowlkes, Jason D.

AU - Boldman, Walker L.

AU - Gu, Genda

AU - Li, Qiang

AU - Feng, Guang

AU - Rack, Philip D.

PY - 2019/5/15

Y1 - 2019/5/15

N2 - Ionic liquids (ILs) have been investigated extensively because of their unique ability to form the electric double layer (EDL), which induces high electrical field. For certain materials, lowerature IL charging is needed to limit the electrochemical etching. Here, we report our investigation of the lowerature charging dynamics in two widely used ILs-DEME-TF2N and C4mim-TF2N. Results show that the formation of the EDL at â220 K requires several hours relative to milliseconds at room temperature, and an equivalent voltage Ve is introduced as a measure of the EDL formation during the biasing process. The experimental observation is supported by molecular dynamics simulation, which shows that the dynamics are logically a function of gate voltage, time, and temperature. To demonstrate the importance of understanding the charging dynamics, a 140 nm thick FeSe0.5Te0.5 film was biased using the DEME IL, showing a tunable Tc between 18 and 35 K. Notably, this is the first observation of the tunability of the Tc in thick film FeSe0.5Te0.5 superconductors.

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