SUPERCONDUCTING UPT3 UNDER PRESSURE

Recent measurements show that the two low-temperature superconducting phases Of UPt3 have very different responses to applied pressure, and suggest that there are three distinct superconducting phases when pressure and temperature are varied. It is shown that these features follow from the two-component theory of unconventional superconductivity, in which the superconducting order parameter couples to the antiferromagnetic order parameter. Within this picture a full theory for the phase diagram of UPt3 in three-dimensional magnetic-field-pressure-temperature space is obtained that agrees quantitatively with measurements. Predictions for future experiments are presented.