UC Irvine

Ultrasound experiments were performed on single crystals of the heavy Fermion superconductor UPt3. From the ultrasound attenuation below Tc, a quasiparticle density of states linear in energy is deduced, which we interpret as due to an anisotropic polar-like (triplet) superconducting state. This is further supported by the agreement of the only fitting parameter Δ0/kTc with the theoretical value for polar p-wave pairing. The attenuation in the normal state gives the electron-phonon interaction strength and the product of the deformation potential times the effective mass is found to be the same as for ordinary ''light'' Fermion systems. The observed variations of the sound velocity are discussed.