QUANTUM TUNNELING OF VORTICES IN CUPRATE AND HEAVY-FERMION SUPERCONDUCTORS

In high-T(c) and in heavy fermion superconductors at low enough temper atures, pinned vortices move from one potential well to another mainly by quantum tunneling. In the superconducting cuprates, the measured c reep rates at low magnetic induction and in the T --> 0 limit are in e xcellent agreement with the values calculated within the framework of the Quantum Collective Creep theory. In the heavy fermion superconduct or UPt3, the measured rates at T --> 0 are much higher than the theore tical values, giving evidence that the low temperature motion of vorti ces in this material is possibly related to its unconventional charact er.