Record high T<sub>c</sub> element superconductivity achieved in titanium.

Zhang, Changling; He, Xin; Liu, Chang; Li, Zhiwen; Lu, Ke; Zhang, Sijia; Feng, Shaomin; Wang, Xiancheng et al. · Nat Commun · 2022

basic_science · Level V

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Abstract

It is challenging to search for high T<sub>c</sub> superconductivity (SC) in transition metal elements wherein d electrons are usually not favored by conventional BCS theory. Here we report experimental discovery of surprising SC up to 310 GPa with T<sub>c</sub> above 20 K in wide pressure range from 108 GPa to 240 GPa in titanium. The maximum T<sub>c</sub><sup>onset</sup> above 26.2 K and zero resistance T<sub>c</sub><sup>zero</sup> of 21 K are record high values hitherto achieved among element superconductors. The H<sub>c2</sub>(0) is estimated to be ∼32 Tesla with coherence length 32 Å. The results show strong s-d transfer and d band dominance, indicating correlation driven contributions to high T<sub>c</sub> SC in dense titanium. This finding is in sharp contrast to the theoretical predications based on pristine electron-phonon coupling scenario. The study opens a fresh promising avenue for rational design and discovery of high T<sub>c</sub> superconductors among simple materials via pressure tuned unconventional mechanism.