High-Current Superconductivity

The Bardeen, Cooper, and Schrieffer theory of superconductivity is extended to the case of high current densities by explicity including in the phonon-induced electron-electron attraction the modification of the phonon spectrum in a moving coordinate system. This modification results from the Doppler effect. In materials having cross-sectional dimensions of the order of the penetration depth, it is shown that at current densities of the order of ${10}^{9}$ amp/${\mathrm{cm}}^{2}$ the superconducting state is stable relative to the normal state, this holding both in superconducting metals and in metals ordinarily not considered superconducting at all. For this high-current state, it appears possible to obtain superconducting transition temperatures as high as room temperature. Means for achieving such an effect experimentally are discussed.