The Dominance of Non-electron-phonon Charge Carrier Interaction in Highly-compressed Superhydrides

Open Access

Abstract

The primary mechanism governing the emergence of near-room-temperature superconductivity (NRTS) in superhydrides is widely accepted to be the electron-phonon interaction. If so, the temperature-dependent resistance, R(T), in these materials should obey the Bloch-Grüneisen (BG) equation, where the power-law exponent, p, should be equal to the exact integer value of p= 5. However, there is a well-established theoretical result showing that the pure electron-magnon interaction should be manifested by p= 3, and p= 2 is the value for pure electron-electron interaction. Here we aimed to reveal the type of charge carrier interaction in the layered transition metal dichalcogenides PdTe2, high-entropy alloy (ScZrNb)0.65[RhPd]0.35 and highly-compressed elemental boron and superhydrides H3S, LaH x, PrH9 and BaH12 by fitting the temperature-dependent resistance of these materials to the BG equation, where the power-law exponent, p, is a free-fitting parameter. The results showed that the high-entropy alloy (ScZrNb)0.65[RhPd]0.35 exhibited pure electron-phonon mediated superconductivity with p = 4.9 0.4. Unexpectedly, we revealed that all studied superhydrides exhibit 1.8 < p < 3.2. This implies that it is unlikely that the electron-phonon interaction is the primary mechanism for the Cooper pairs formation in highly-compressed superhydrides, and alternative pairing mechanisms, for instance, the electron-magnon, the electron-polaron, the electron-electron and other pairing mechanisms should be considered as the origin for the emergence of NRTS in these compounds. © 2021 IOP Publishing Ltd. ; The author is grateful for financial support provided by the Ministry of Science and Higher Education of Russia (theme 'Pressure' No. AAAA-A18-118020190104-3) and by Act 211 Government of the Russian Federation, Contract No. 02.A03.21.0006.