UHの水素化物研究が実用的で身近な超伝導のフロンティアを押し広げる(University of Houston Hydride Research Pushes Frontiers of Practical, Accessible Superconductivity)

2024-04-29 ヒューストン大学(UH)

＜関連情報＞

• https://uh.edu/news-events/stories/2024/april/04292024-superconductivity-hydrides.php
• https://www.nature.com/articles/s41467-024-46133-x
• https://iopscience.iop.org/article/10.1088/1361-648X/ad0915

イットリウム-セリウム水素化物の高圧合成と超伝導 Synthesis and superconductivity in yttrium-cerium hydrides at high pressures

Liu-Cheng Chen,Tao Luo,Zi-Yu Cao,Philip Dalladay-Simpson,Ge Huang,Di Peng,Li-Li Zhang,Federico Aiace Gorelli,Guo-Hua Zhong,Hai-Qing Lin & Xiao-Jia Chen
Nature Communications  Published:28 February 2024
DOI:https://doi.org/10.1038/s41467-024-46133-x

Abstract

Further increasing the critical temperature and/or decreasing the stabilized pressure are the general hopes for the hydride superconductors. Inspired by the low stabilized pressure associated with Ce 4f electrons in superconducting cerium superhydride and the high critical temperature in yttrium superhydride, we carry out seven independent runs to synthesize yttrium-cerium alloy hydrides. The synthetic process is examined by the Raman scattering and X-ray diffraction measurements. The superconductivity is obtained from the observed zero-resistance state with the detected onset critical temperatures in the range of 97-141 K. The upper critical field towards 0 K at pressure of 124 GPa is determined to be between 56 and 78 T by extrapolation of the results of the electrical transport measurements at applied magnetic fields. The analysis of the structural data and theoretical calculations suggest that the phase of Y_0.5Ce_0.5H₉ in hexagonal structure with the space group of P6₃/mmc is stable in the studied pressure range. These results indicate that alloying superhydrides indeed can maintain relatively high critical temperature at relatively modest pressures accessible by laboratory conditions.

高圧下でのLa0.5Ce0.5H10の超伝導相の合成 Synthesis of superconducting phase of La0.5Ce0.5H10 at high pressures

Ge Huang, Di Peng, Tao Luo, Liu-Cheng Chen, Philip Dalladay-Simpson, Zi-Yu Cao, Federico A Gorelli, Guo-Hua Zhong, Hai-Qing Lin and Xiao-Jia Chen
Journal of Physics: Condensed Matter  Published 10 November 2023
DOI:10.1088/1361-648X/ad0915

Abstract

Clathrate hydride 3¯-LaH₁₀ has been proven as the most extraordinary superconductor with the critical temperature T_c above 250 K upon compression of hundreds of GPa in recent years. A general hope is to reduce the stabilization pressure and maintain the high T_c value of the specific phase in LaH₁₀. However, strong structural instability distorts 3¯ structure and leads to a rapid decrease of T_c at low pressures. Here, we investigate the phase stability and superconducting behaviors of 3¯-LaH₁₀ with enhanced chemical pre-compression through partly replacing La by Ce atoms from both experiments and calculations. For explicitly characterizing the synthesized hydride, we choose lanthanum-cerium alloy with stoichiometry composition of 1:1. X-ray diffraction and Raman scattering measurements reveal the stabilization of 3¯-La_0.5Ce_0.5H₁₀ in the pressure range of 140–160 GPa. Superconductivity with T_c of 175 ± 2 K at 155 GPa is confirmed with the observation of the zero-resistivity state and supported by the theoretical calculations. These findings provide applicability in the future explorations for a large variety of hydrogen-rich hydrides.