Quantum-Dimensional Effects In The Positron Annihilation Spectra Of La–Ba–Cu–O Superconductors
This paper is devoted to explain the anisotropy phenomena of angular distribution annihilation photons (ADAP) in mono-crystalline La—Ba—Cu—O high temperature superconductors (HTSC) with alternating conductive (Cu—O(1)) and nonconductive (La—O(2)) layers. It is shown that the basic contribution to the anisotropy of ADAP spectra is connected with positron annihilation in the conductive Cu—O(1) layers. To describe the behavior of conduction electrons in the Cu—O(1) layer, the 2D model of a free Fermi gas was used. In the transverse direction, electron states are described in model one-dimensional potential well. It is shown that in the transverse direction the ADAP spectra possess several “plateaus” corresponding to positions of allowed electron states, while in longitudinal direction the ADAP spectra posses a parabolic form.
Keywordselectron—positron annihilation anisotropy high-temperature superconductors quantum dimensional effects
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