Magnetic-exciton-mediated superconductivity in UPd2Al3

There is compelling evidence from inelastic neutron scattering and tunnelling experiments that the heavy fermion superconductor UPd2Al3 can be understood as a dual system consisting of magnetic excitons, arising from crystal-field-split U4+ levels, coupled to delocalised f electrons [N. Sato, et al., Nature 410 (2001) 340 [1]]. We have computed the superconducting transition temperature and the mass renormalisation arising from a dual model with maximal spin anisotropy using a strong-coupling approach [P. McHale, et al., Phys. Rev. B 70 (2004) 014513 [2]]. We find that superconducting states with a line node in the ab-plane are favoured in agreement with NMR relaxation-rate, specific-heat and thermal-conductivity measurements. The signature of line nodes on the low temperature field-angle resolved magnetothermal conductivity in the vortex phase of UPd2Al3, as investigated in T. Watanabe, et al., cond-mat/0405211 [3], is studied within the Doppler shift approximation for the quasiparticle energies.