Ultrasonic Attenuation in Superconducting Aluminum Containing Dislocations

Abstract

Superconductivity is one of the most important consequences of the electron-phonon interaction. It has generally been believed that the superconductivity was rather a structure-insensitive property, because it was an ordered state of free electrons in k-space. But the circumstance seems to be somewhat altering. Recent studies on a variety of superconducting materials, for example those with the A15 structure and with the disordered state, have suggested the importance of the effect of atomic configuration on the superconductivity. The present study is intended to investigate the effect of crystal dislocations on the superconductivity of very pure aluminum crystals. An ultrasonic method can conveniently be used for the purpose. We have successfully determined the anisotropy of superconducting energy gap in aluminum [1], and the subsequent studies on the dislocated state of the material are described in this paper.