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Superconducting properties of (NH3)yLixFeSe0.5Te0.5 under pressure.

Authors :
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
Source :
New Journal of Physics; Nov2019, Vol. 21 Issue 11, p1-8, 8p
Publication Year :
2019

Abstract

We prepared two superconducting phases of (NH<subscript>3</subscript>)<subscript>y</subscript>Li<subscript>x</subscript>FeSe<subscript>0.5</subscript>Te<subscript>0.5</subscript>, which show superconducting transition temperatures (T<subscript>c</subscript>'s) as high as 20.2 and 29.5 K at ambient pressure, here called the 'low-T<subscript>c</subscript> phase' and 'high-T<subscript>c</subscript> phase'. The temperature dependence of electrical resistance (R) was measured for the low-T<subscript>c</subscript> phase of (NH<subscript>3</subscript>)<subscript>y</subscript>Li<subscript>x</subscript>FeSe<subscript>0.5</subscript>Te<subscript>0.5</subscript> over a pressure (p) range of 0–14 GPa, and for the high-T<subscript>c</subscript> phase of (NH<subscript>3</subscript>)<subscript>y</subscript>Li<subscript>x</subscript>FeSe<subscript>0.5</subscript>Te<subscript>0.5</subscript> over 0–19 GPa, yielding double-dome superconducting T<subscript>c</subscript>–p phase diagrams, i.e. two superconducting phases (SC-I and SC-II) were found for both the low-T<subscript>c</subscript> and high-T<subscript>c</subscript> phases under pressure. For the low-T<subscript>c</subscript> phase, the maximum T<subscript>c</subscript> 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<subscript>c</subscript> phase, the maximum T<subscript>c</subscript> 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<subscript>c</subscript> 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<subscript>c</subscript>–p phase diagrams of (NH<subscript>3</subscript>)<subscript>y</subscript>Li<subscript>x</subscript>FeSe and (NH<subscript>3</subscript>)<subscript>y</subscript>Cs<subscript>x</subscript>FeSe investigated previously. Nevertheless, the double-dome T<subscript>c</subscript>–p phase diagram was found in metal-doped FeSe<subscript>0.5</subscript>Te<subscript>0.5</subscript>, indicating that this feature is universal in metal-doped FeSe<subscript>1−z</subscript>Te<subscript>z</subscript>. Moreover, no structural phase transitions were observed for either the low-T<subscript>c</subscript> or high-T<subscript>c</subscript> phases of (NH<subscript>3</subscript>)<subscript>y</subscript>Li<subscript>x</subscript>FeSe<subscript>0.5</subscript>Te<subscript>0.5</subscript> over the wide pressure range of 0–15.3 GPa, and the T<subscript>c</subscript>-lattice constant (c) plots for both phases were recorded to determine the critical point separating SC-I and SC-II. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
13672630
Volume :
21
Issue :
11
Database :
Complementary Index
Journal :
New Journal of Physics
Publication Type :
Academic Journal
Accession number :
152287950
Full Text :
https://doi.org/10.1088/1367-2630/ab5034