Optimal alloying in hydrides: Reaching room-temperature superconductivity in LaH10

Nov. 29 17:15-17:30

*Tianchun Wang1, José A. Flores-Livas2,3, Takuya Nomoto4, Yanming Ma5,6, Takashi Koretsune7, Ryotaro Arita3,4
Department of Applied Physics, The University of Tokyo1
Dipartimento di Fisica, Università di Roma La Sapienza2
RIKEN Center for Emergent Matter Science3
Research Center for Advanced Science and Technology, The University of Tokyo4
State Key Laboratory of Superhard Materials, College of Physics, Jilin University5
International Center of Future Science, Jilin University6
Department of Physics, Tohoku University7

Doping represents one of the most promising avenues for optimizing superconductors, such as reaching record-breaking critical temperatures of hydride superconductors. In this work, we perform an thorough and extensive search for substitutional dopants in LaH10, looking for elements that enhance its electronic structure (especially the density of states at the Fermi level). In total, 70 elements were investigated as possible substitutions of La-sites at the doping ratio of 12.5% under high pressure. By using our systemetical and efficient screening protocal, we found Ca as the best candidate dopants, which shift the van Hove singularity and increase the electronic DOS at the Fermi level. With harmonic-level phonon calculations and performin first-principles calculation of Tc, Ca-doped LaH10 shows Tc which is 15% higher than the one of LaH10. It provides a promising route to reach the room-temperature superconductivity in pressurized hydrides by doping.

Fig. 1: Geometry relaxation results of LaH10 doped by different elements with doping ratio of 12.5% at 150 GPa pressure, and different color code gives the behavor for different elements. (a) The periodic table with elements classified to four types of relaxation results. (b) Typical elements with corresponding structural patterns after relaxations for four cases. At the doping ratio of 12.5%, most of the elements destabilized the symmetric pattern, and only 3 elements preserve the high symmetry.

Keywords: Hydride superconductors, Impurities in superconductors, First-principles calculation, van Hove singularity