超导电性
亚稳态
凝聚态物理
软化
配对
声子
格子(音乐)
材料科学
高压
从头算
联轴节(管道)
从头算量子化学方法
热力学
物理
量子力学
声学
冶金
复合材料
分子
作者
Antonio Sanna,Camilla Pellegrini,Simone Di Cataldo,G. Profeta,Lilia Boeri
出处
期刊:Cornell University - arXiv
日期:2023-01-01
标识
DOI:10.48550/arxiv.2308.14672
摘要
Motivated by unexpected reports of a 26 K superconducting transition in elemental titanium at high pressure, we carry out an accurate ab-initio study of its properties to understand the rationale for this observation. The critical superconducting temperatures (Tc's) predicted under the assumption of a phononic pairing mechanism are found to be significantly lower than those experimentally observed. We argue that this disagreement cannot be explained by an unconventional coupling, as previously suggested, or by the existence of competing metastable structural phases. As a physically meaningful hypothesis to reconcile experimental and theoretical results, we assume the presence of Ti vacancies in the lattice. Our first-principles calculations indeed show that lattice vacancies can cause pressure dependent phonon softening and substantially increase the electron-phonon coupling at high pressure, yielding computed Tc's in agreement with the experimental measurements over the full pressure range from 150 to 300 GPa. We expect the proposed Tc enhancement mechanism to occur on a general basis in simple high-symmetry metals for various types of defects.
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