Collective vibrations of phase boundaries in high-temperature superconductors

The conditions of emergence of surface waves with the dispersion relation ω ∝ k1/2 typical of two-dimensional plasmons and the region of existence of these waves are analyzed for a triple solid-state system A–B–A. Excitation of this kind were used by Horovitz et al. /Phys. Rev. B36, 8895 (1987)/ to explain anomalies in low-temperature thermodynamic and kinetic characteristics of HTS. It is shown that the region of existence of such oscillations noticeably expands in the vicinity of a structural phase transition enhancing the elastic anisotropy of the system. The conditions of “optimal” geometry of phase conjugation, in which collective excitations of the type under consideration emerge are formulated. In the general case, the close densities of contacting phases and delay effects of acoustic waves in a crystal impose strict limitations on the region of existence of such excitations, which makes their noticeable contribution to thermodynamics and kinetics of HTS improbable.

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