MAGNETOSTRICTION OF SUPERCONDUCTORS

摘要

There are two known origins of magnetostriction phenomena in superconductors. The first is thermodynamic, associated with the variat on of the condensation energy with magnetic field. The effect caused by this mechanism is reversible with relative length changes ΔL/L of the order of 10~(-7). The second mechanism relates to a non-uniform distribution of magnetic flux in realistic type-II superconductors due to pinning of vortices by defects of the lattice. Magnetostriction in this case is hysteretic and ΔL/L, can be as large as 10~(-4). Study of pinning and corresponding density of the superconducting current is among the hottest subjects in the ongoing worldwide research of modern superconductivity. Experimen al studies are in many cases limited to magnetization measurements only, which do not allow an unambiguous selection among numerous models and fitting parameters, The lecture will, therefore, be mainly devoted to what can be and should be done to promote the study of superconductivity using the magnetostriction technique. Relatively scarce existing data will be overviewed. Examples of unusual behavior both in low and high temperature superconductors will be discussed.