Superconducting properties of (NH3) y Li x FeSe0.5Te0.5 under pressure

Xiaofan Yang, Tong He, Tomoya Taguchi, Huan Li, Yanan Wang, Hidenori Goto, Ritsuko Eguchi, Takafumi Miyazaki, Hitoshi Yamaoka, Hirofumi Ishii, Yen Fa Liao, Yoshihiro Kubozono

Research output: Contribution to journalArticlepeer-review


We prepared two superconducting phases of (NH3) y Li x FeSe0.5Te0.5, which show superconducting transition temperatures (T c's) as high as 20.2 and 29.5 K at ambient pressure, here called the 'low-T c phase' and 'high-T c phase'. The temperature dependence of electrical resistance (R) was measured for the low-T c phase of (NH3) y Li x FeSe0.5Te0.5 over a pressure (p) range of 0-14 GPa, and for the high-T c phase of (NH3) y Li x FeSe0.5Te0.5 over 0-19 GPa, yielding double-dome superconducting T c-p phase diagrams, i.e. two superconducting phases (SC-I and SC-II) were found for both the low-T c and high-T c phases under pressure. For the low-T c phase, the maximum T c was 20.2 K at 0 GPa for SC-I, and 19.9 K at 8.98 GPa for SC-II. For the high-T c phase, the maximum T c was 33.0 K at 1.00 GPa for SC-I, and 24.0 K at 11.5-13.2 GPa for SC-II. These results imply that the maximum T c value of the high pressure phase (SC-II) does not exceed the maximum value of the SC-I, unlike what was shown in the T c-p phase diagrams of (NH3) y Li x FeSe and (NH3) y Cs x FeSe investigated previously. Nevertheless, the double-dome T c-p phase diagram was found in metal-doped FeSe0.5Te0.5, indicating that this feature is universal in metal-doped FeSe1-zTe z . Moreover, no structural phase transitions were observed for either the low-T c or high-T c phases of (NH3) y Li x FeSe0.5Te0.5 over the wide pressure range of 0-15.3 GPa, and the T c-lattice constant (c) plots for both phases were recorded to determine the critical point separating SC-I and SC-II.

Original languageEnglish
Article number113010
JournalNew Journal of Physics
Issue number11
Publication statusPublished - Nov 6 2019


  • crystal structure
  • metal intercalated FeSeTeTe
  • phase diagram
  • pressure
  • superconductivity

ASJC Scopus subject areas

  • General Physics and Astronomy


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