Magnetoresistance of UPt3

We have performed measurements of the temperature dependence of the magnetoresistance up to 9 T in bulk single crystals of UPt3 with the magnetic field along the b axis, the easy magnetization axis. We have confirmed previous results for transverse magnetoresistance with the current along the c axis, and report measurements of the longitudinal magnetoresistance with the current along the b axis. The presence of a linear term in both cases indicates broken orientational symmetry associated with magnetic order. With the current along the c axis the linear term appears near 5 K, increasing rapidly with decreasing temperature. For current along the b axis the linear contribution is negative.Comment: 6 pages, 3 figures, submitted to Quantum Fluids and Solids Conference (QFS 2006

Inductive measurements of UPt3 in the superconducting state

The inductive response of several UPt3 samples obtained from four different materials-fabrication groups has been measured from 50 to 700 mK at frequencies varying between 32 Hz and 33 MHz. The temperature dependence of the penetration depth, (T), is presented for each sample. The low-frequency (4.7 kHz) data suggest a linear temperature dependence of (T/Tc 0.5) for the samples possessing a double feature near the superconducting transition temperature Tc. We have verified that this double feature present in (T) for some of the samples corresponds to the double jump observed in the specific heat. On the other hand, (T/Tc 0.5) is found to have a quadratic temperature dependence for unannealed specimens which exhibit only a single transition at Tc. The linear temperature dependence of (T) is consistent with the presence of line nodes in the basal plane, while the quadratic dependence found for other samples suggests that impurity scattering dominates in these specimens. The double transition in (T) has been studied in magnetic fields up to 1.6 T, and the resulting phase diagram is consistent with the one constructed from thermodynamical measurements. The high-frequency (3 MHz) data suggest (T/Tc 0.5) T, where 2 4. The possible origins of the frequency dependence of (T) are discussed, as well as the effect of the surface quality on. © 1995 The American Physical Society