2022年第83回応用物理学会秋季学術講演会

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一般セッション(口頭講演)

11 超伝導 » 11.1 基礎物性

[22a-A302-1~8] 11.1 基礎物性

2022年9月22日(木) 09:15 〜 11:30 A302 (A302)

加藤 雅恒(東北大)、石田 茂之(産総研)

10:00 〜 10:15

[22a-A302-4] Potential high-Tc superconductivity in YCeH20 and LaCeH20 under pressure

HOU SOU1、Kousuke Nakano1、Kenta Hongo2、Ryo Maezono1 (1.Inf. Sci. JAIST、2.RCACI. JAIST)

キーワード:superconductor, electron-phonon coupling, superconducting hydride

Lanthanum, yttrium, and cerium hydrides are the three most well-known superconducting binary hydrides, which have gained great attention in both theoretical and experimental studies. Recent studies have shown that ternary hydrides composed of lanthanum and yttrium can achieve high superconductivity around 253 K. In this study, we employ the evolutionary-algorithm-based crystal structure prediction (CSP) method and first-principles calculations to investigate the stability and superconductivity of ternary hydrides composed of (Y, Ce) and (La, Ce) under high pressure. Our calculations show that there are multiple stable phases in Y-Ce-H and La-Ce-H hydrides, among which P4/mmm-YCeH8, P4/mmm- LaCeH8, R-3m-YCeH20, and R-3m-LaCeH20 possessing H18 or H32 clathrate structures can maintain both of the thermodynamic and dynamic stabilities. In addition, we also find that these phases also maintain a strong resistance to decomposition at high temperatures. Electron-phonon coupling calculations show that all of these four phases can exhibit high-temperature superconductivity. R-3m-YCeH20 is predicted to have a superconducting transition temperature (Tc) as high as 246 K at 350 GPa. The Tc value of R-3m-LaCeH20 at 250 GPa is about 233 K, which is slightly smaller than that of R-3m- YCeH20. However, it is found that R-3m-LaCeH20 can be stabilized at 200 GPa, making the high-pressure synthesis of LaCeH20 easier.