Controlled symmetry breaking in superconducting UPt_3

We have developed a biaxial-stress calorimeter for use at milli-Kelvin temperatures to study the nature of the double superconducting transition in single crystal UPt_3. We suppress the basal-plane antiferromagnetism and merge the two transitions through c-axis stress, and then break the hexagonal symmetry of the basal plane in a regulated manner through stress along â. We recover a double superconducting transition, but with a shift in the relative sizes of the specific heat jumps for the upper and lower transitions, as well as a different measure of the strength of the symmetry-breaking field.