PARAMAGNETIC MEISSNER EFFECT FROM THE SELF-CONSISTENT SOLUTION OF THEGINZBURG-LANDAU EQUATIONS

The paramagnetic Meissner effect (PME), recently observed in high-T-c materials and also in Nb, can be successfully explained by the persist ence of a giant vortex state with a fixed orbital quantum number L. Th is state is formed in superconductors in the field-cooled regime at th e third critical field. The self-consistent numerical solution of the Ginzburg-Landau equations clearly shows that the compression of the fl ux trapped inside the giant vortex state can result in the PME. The PM E is suppressed, and the normal diamagnetic response is recovered, by increasing the applied field. A possible definition of the irreversibi lity line, as a crossover between the giant vortex state and the Abrik osov flux line lattice, is discussed. The transition between the two q uantum states (L = 0 and L = 1) has been used to calculate the field H 0-->1(T), corresponding to the penetration of the first flux line into a cylindrical sample.