| Eff ect of alkali metal deintercalation on superconductivity in the KxFe2–ySe2 system |
| Sung-Hun Kim1,2, Jong-Young Kim2, Wooyoung Shim1 |
1Department of Materials Sciences and Engineering, Multi-Scale Materials Laboratory, Yonsei University, 50, Yonsei-ro, Seodaemun-gu, Seoul, Republic of Korea
2Icheon Branch , Korea Institute of Ceramic Engineering and Technology (KICET), 3321, Gyeongchung Rd., Sindun-Myeon, Icheon, Kyeonggi-do 467-843, Republic of Korea |
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Received: June 10, 2020; Revised: July 21, 2020 Accepted: July 26, 2020. Published online: November 30, 2020. |
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| ABSTRACT |
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In this work, the intercalation and subsequent deintercalation of alkali metal (K) were performed on new tetragonal β-FeSe compounds, and the eff ect on their superconductivity was studied. The FeSe precursor was intercalated with potassium by solid-state reaction, and then the potassium was selectively etched by topochemical reaction with polar chemical solvents. The K-intercalated FeSe showed phase separation, into a major insulating phase with Fe vacancy and a minor superconducting phase without vacancy. After the topotactic deintercalation reaction, the deintercalated FeSe exhibited increased lattice parameters compared to the pristine FeSe compound, and antiferromagnetic behavior instead of superconductivity. The magnetic property can be attributed to the phase separation of the K-intercalated phases. The deintercalated phase retained the β-FeSe structure with Fe vacancies, which changed the superconductor to an antiferromagnetic metal. |
| Key words:
Superconductivity · Superconductor · Intercalation · Deintercalation |
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