Fluctuations above Tc and the kinetic energy of Cooper pairs in La1.9Sr0.1CuO4 and Pb0.55In0.45

The kinetic energy of the superconducting state of Pb-In and La-SrCuO is shown to be quite distinct although both compounds are known to present magnetic fluctuations in a wide temperature range above T-c. While Pb-In isofield kinetic-energy curves cross each other, and show a predominant mean-field behavior, as observed in the magnetization, similar curves for La-SrCuO do not cross each other, just being continuously dislocated to the high-temperature direction, smoothly extending above T-c. We show that the La-SrCuO isofield kinetic curves obey scaling near the transition and this can be viewed either as the existence of thermal fluctuations or as a sign of a new temperature scale T-e.