Thermal Conductivity Anisotropy in Superconducting UPt3UPt_3

Recent thermal conductivity measurements on $UPt_3$ single crystals by Lussier et al. indicate the existence of a strong b--c anisotropy in the superconducting state. We calculate the thermal conductivity in various unconventional candidate states appropriate for the $UPt_3$ ``B phase" and compare with experiment, specifically the $E_{2u}$ and $E_{1g}$ $(1,i)$ states predicted in some Ginzburg-Landau analyses of the phase diagram. For the simplest realizations of these states over spherical or ellipsoidal Fermi surfaces, the normalized $E_{2u}$ conductivity is found, surprisingly, to be completely isotropic. We discuss the effects of inelastic scattering and realistic Fermi surface anisotropy, and deduce constraints on the symmetry class of the $UPt_3$ ground state.Comment: 4 postscript pages, UFL102

Theory of "ferrisuperconductivity" in U1−xThxBe13U_{1-x}Th_xBe_{13}

We construct a two component Ginzburg-Landau theory with coherent pair motion and incoherent quasiparticles for the phase diagram of $U_{1-x}Th_xBe_{13}$. The two staggered superconducting states live at the Brillouin zone center and the zone boundary, and coexist for temperatures $T\le T_{c2}$ at concentrations $x_{c1}\approx 0.02\le x \le x_{c2}\approx 0.04$. We predict below $T_{c2}$ appearance of a charge density wave (CDW) and Be-sublattice distortion. The distortion explains the $\mu$SR relaxation anomaly, and Th-impurity mediated scattering of ultrasound to CDW fluctuations explains the attenuation peak.Comment: 4 pages, 4 eps figures, REVTe

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