Nonmonotonic magnetic-field dependence and scaling of the thermal conductivity for superconductors with nodes of the order parameter

We show that there is a mechanism for the nonmonotonic behavior of the magnetic-field dependence of the electronic thermal conductivity kappa of clean superconductors with nodes of the order parameter on the Fermi surface. In particular, for unitary scatterers the nonmonotony of the relaxation time takes place. A contribution from the intervortex space turns out to be essential for this effect even at low temperatures. Our results are in a qualitative agreement with recent experimental data for superconducting UPt3. For E-2u-type pairing we find approximately the scaling of the thermal conductivity in the clean limit with a single parameter x =(T/T-c)root B-c2/B at low fields and low temperatures, as well as a weak low-temperature dependence of the anisotropy ratio kappa(zz)/kappa(yy) in zero field. For E-1g-type pairing deviations from the scaling are more noticeable and the anisotropy ratio is essentially temperature dependent.