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 journalArticle

Abstract

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
Volume21
Issue number11
DOIs
Publication statusPublished - Nov 6 2019

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phase diagrams
domes
electrical resistance
metals
critical point
plots
transition temperature
temperature dependence

Keywords

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

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Superconducting properties of (NH3) y Li x FeSe0.5Te0.5 under pressure. / Yang, Xiaofan; He, Tong; Taguchi, Tomoya; Li, Huan; Wang, Yanan; Goto, Hidenori; Eguchi, Ritsuko; Miyazaki, Takafumi; Yamaoka, Hitoshi; Ishii, Hirofumi; Liao, Yen Fa; Kubozono, Yoshihiro.

In: New Journal of Physics, Vol. 21, No. 11, 113010, 06.11.2019.

Research output: Contribution to journalArticle

Yang, Xiaofan ; He, Tong ; Taguchi, Tomoya ; Li, Huan ; Wang, Yanan ; Goto, Hidenori ; Eguchi, Ritsuko ; Miyazaki, Takafumi ; Yamaoka, Hitoshi ; Ishii, Hirofumi ; Liao, Yen Fa ; Kubozono, Yoshihiro. / Superconducting properties of (NH3) y Li x FeSe0.5Te0.5 under pressure. In: New Journal of Physics. 2019 ; Vol. 21, No. 11.
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AU - He, Tong

AU - Taguchi, Tomoya

AU - Li, Huan

AU - Wang, Yanan

AU - Goto, Hidenori

AU - Eguchi, Ritsuko

AU - Miyazaki, Takafumi

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AU - Ishii, Hirofumi

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AU - Kubozono, Yoshihiro

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N2 - 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.

AB - 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.

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KW - phase diagram

KW - pressure

KW - superconductivity

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