Fundamental Limits on the Electron-Phonon Coupling and Superconducting T<sub>c</sub>.

Semenok, Dmitrii V; Altshuler, Boris L; Yuzbashyan, Emil A · Adv Mater · 2025

basic_science · Level V

Where this comes from

Abstract

Fundamental upper bounds on the electron-phonon interaction strength and superconducting transition temperature T<sub>c</sub> in metals are established based on the intrinsic instability of the equilibrium between electrons and the crystal lattice under strong interaction. This instability explains why observed electron-phonon coupling constants are limited to λ ≲ 4. The theory also accounts for the mechanism of metastable superconductivity with enhanced T<sub>c</sub>, which emerges near the instability threshold. Based on theoretical analysis and comparison with experimental data, room-temperature phonon-mediated superconductivity is found to be feasible exclusively in hydrogen compounds.