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



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.

ジャーナルNew Journal of Physics
出版ステータスPublished - 11月 6 2019

ASJC Scopus subject areas

  • 物理学および天文学一般


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