Zigzag filamentary theory of longitudinal optical phonons in high-temperature superconductors

Abstract

Anomalous features (dispersive gaps and pseudogaps) have been observed by inelastic neutron scattering in the longitudinal optical bond-stretching vibrational spectra of superconductive (Ba_0.6K_0.4BiO₃) and ferromagnetic (La_1−xSr_xMnO₃) doped perovskites, as well as in layered superconductive pseudoperovskite cuprates La_2−xSr_xCuO₄ (x = 0.15) and YBa₂Cu₃O_6−x (x = 0.20, 0.35, 0.60 and 0.93). These anomalies are explained by a microscopic theoretical model which is compatible with the only known satisfactory fundamental model of superconductivity, namely the Bardeen–Cooper–Schrieffer theory. The model assumes that the dopants are self-organized into chains and planes with short-range orders of special symmetries.