A new kind of electron-lattice interaction and the kinetics of breaking high-T c and low-T c superconductivity via large thermal energy fluctuations of lattice particles

Abstract

A novel kind of a strong electron-lattice interaction in high-T c (HTSC's) and conventional low-T c (LTSC's)superconductors mediated by short-lived large energy fluctuations (SLEF's) of lattice atoms (ions) of lifetime Δτ≈10−13−10−12s, is considered and applied to the kinetics of thermal pair-breaking in the HTSC's and LTSC's. The transition from the superconducting (SC) state into a non-SC state at temperaturesT c in HTSC's or LTSC's is caused by a great number of SC pair-SLEF collisions each of which breaks the local quantum coherence and creates a local instability of the SC state. Quantum macroscopic percolation-like phenomena appear in HTSC's or LTSC's and destroy the SC state atT→T c when the mean distance between the simultaneously existing SLEF-induced local instabilities becomes of the order of the SC coherence length ζ. The transition temperaturesT c and pairing energies 2 Δ as well as coupling constants in HTSC's and LTSC's are calculated and linked with some material parameters (the elasticity modulus, Debye temperature, SC pair density, etc.) through a modification of our earlier proposed theory of SLEF's and electron-SLEF interactions (Phys. Rep.99, 237 (1983) and Phys. Rev. B33, 2983 (1986)). Quasi-2-dimensional properties of carriers in HTSC's and the 3-dimensional nature of SC electrons in LTSC's are taken into account. The obtained new exponential equations for 2 Δ have pre-exponential factor ℏωF≈ℏv F/d determined by the Fermi velocityv F and the interatomic distanced. The transition temperature shows only a weak, if at all, isotope in HTSC's and the conventional isotope effect in LTSC's, in agreement with observations. Numerical estimates ofT c and 2 Δ are in agreement with experimental data for both HTSC's and LTSC's. The comparison of HTSC and LTSC properties is discussed.