UNIVERSAL TREND IN THE HEAT-CAPACITY OF YBA2CU3O7-X NEAR T(C)(X)

The reduction in transition temperature that occurs as oxygen is remov ed from YBa2CU307-x is accompanied by a rapid decrease in the size of the heat-capacity anomaly at T(c). We treat the fluctuation effects in the context of XY-like behavior and demonstrate that their dependence on the transition temperature agrees in detail with a relationship be tween T(c) and the hole concentration proposed by Schneider and Keller . Further, we show that this empirical relationship can be understood by combining scaling arguments with the nearly antiferromagnetic Fermi -liquid model of Monthoux and Pines.