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Jeudi 10 décembre 2020 à 14h00
Superconductivity in elemental yttrium and yttrium superhydride at megabars pressures
The quest for room temperature superconductivity has always been one of the most intense topics in condensed matter physics. It has reached its peak with the recent discovery of several superhydride compounds exhibiting superconductivity at vicinity of room temperature [1-6] and at room temperature [7] under megabars pressures. While theoretical works are paving the way to realize new hydrides superconductors, their synthesis within the laboratory remains very challenging. Here we demonstrate a new approach to synthesize YHx from an elemental yttrium film directly evaporated on the diamond anvil [8]. This method allows a more accurate control of the sample size and helps to reach an ideal stoichiometry in the synthesis. Our measurements show that electronic properties of elemental yttrium bulk and film are similar. Superconducting temperatures we measure in elemental yttrium under megabar pressures together with a re-analyse of previous x-ray data provide evidence of the predicted Fddd phase above 100 GPa. Furthermore, I will show that it is possible to synthetize an yttrium superhydride superconductor film.
[1] A. P Drozdov et al., Nature 525, 73 (2015) [2] Z. M. Geballe et al., Angew. Chem. Int. 57, 688 (2018) [3] A. P Drozdov et al., Nature 569, 531 (2019) [4] P.P. Kong et al., arXiv:1909.10482 (2019) [5] I. A. Trojan et al., arXiv:1908.01534 (2019) [6] Dmitry V. Semenok et al., Materials Today 33, 36 (2020) [7] E. Snider et al., Nature 586, 373 (2020) [8] J. Buhot et al., Phys. Rev. B 102, 104508 (2020)
