Defecton Contribution to the High-Temperature Superconductivity of Hydrides

Abstract

Formation of high-temperature superconducting phases of some hydrides requires high pressure (several hundred gigapascals), which causes lattice compression and, correspondingly, exponential increase in the probability of hydrogen-atom tunneling between equivalent interstitial sites. At low temperatures, vacancies in the hydrogen sublattice (occupied under stoichiometric conditions) and hydrogen atoms in the interstitial sublattice (absolutely vacant under stoichiometric conditions) are quantum defects (defectons). The defecton contribution to the superconductivity of hydrides has been estimated. It is shown that this contribution can be large both for free defectons and defectons clusterized with formation of two-level systems.