SPECIFIC-HEAT OF YBA2CU3O7 - ORIGIN OF THE LINEAR TERM AND VOLUME FRACTION OF SUPERCONDUCTIVITY

Correlations of the coefficient of the "linear" term in the specific heat, (0), and the discontinuity at Tc, "C(Tc), with a measured concentration of Cu2+ magnetic moments suggest the operation of a pairbreaking mechanism that limits the transition to the superconducting state and produces a contribution to (0). There is no evidence for the existence of an intrinsic contribution to (0). The value of "C(Tc) for a sample provides a measure of the volume fraction of superconductivity and a basis for correcting measured values of parameters to those characteristic of the fully superconducting state. Estimates of several quantities relevant to the strength of coupling are given. © 1990 The American Physical Society.