Controlled Symmetry Breaking in SuperconductingUPt3

Abstract

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 ${\mathrm{UPt}}_{3}$. We suppress the basal-plane antiferromagnetism and merge the two transitions through $\mathbf{c}$-axis stress, and then break the hexagonal symmetry of the basal plane in a regulated manner through stress along $\stackrel{^}{\mathbf{a}}$. 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.