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Title: Low-Temperature Charging Dynamics of the Ionic Liquid and Its Gating Effect on FeSe0.5Te0.5 Superconducting Films

Journal Article · · ACS Applied Materials and Interfaces
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [2];  [3];  [3];  [4];  [5]; ORCiD logo [5]; ORCiD logo [6]; ORCiD logo [1]
  1. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Huazhong Univ. of Science and Technology (HUST), Wuhan (China)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Univ. of Tennessee, Knoxville, TN (United States)
  5. Brookhaven National Lab. (BNL), Upton, NY (United States)
  6. Huazhong Univ. of Science and Technology (HUST), Wuhan (China); Shenzhen Research Institute of Huazhong Univ. of Science and Technology, Shenzhen (China)

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, low-temperature IL charging is needed to limit the electrochemical etching. Here, we report our investigation of the low-temperature charging dynamics in two widely used ILs—DEME-TF2N and C4mim-TF2N. Results show that the formation of the EDL at ~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.

Research Organization:
Brookhaven National Lab. (BNL), Upton, NY (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
SC0012704; AC05-00OR22725
OSTI ID:
1529071
Alternate ID(s):
OSTI ID: 1546498
Report Number(s):
BNL-211777-2019-JAAM
Journal Information:
ACS Applied Materials and Interfaces, Vol. 11, Issue 19; ISSN 1944-8244
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 7 works
Citation information provided by
Web of Science