UPT3 - SPECIFIC-HEAT, CRITICAL FIELDS, AND THE GINZBURG-LANDAU MODELSFOR THE SUPERCONDUCTING PHASE-DIAGRAM

The superconducting phase diagram Of UPt3 has three important features that can be described by a Ginzburg-Landau model. These features are (i) the double transition in zero field, observable as two peaks in th e specific heat; (ii) the kink in the lower-critical-field curve H(c1) (T); (iii) the kink in the upper-critical-field curve H(c2)(T). We pre sent the observation of all three features for one and the same high-q uality sample. The resultant data are used to test the internal consis tency of two recently published models for the superconducting phase d iagram.