Gap symmetry of superconducting borocarbide YNi2B2C and skutterudite PrOs4Sb12

Abstract

Within the quasiclassical approximation we have studied the thermodynamics and the thermal conductivity in the vortex state in nodal superconductors (sc). Recent angle dependent magnetothermal conductivity results indicate a gap function ∆(k) corresponding to f-wave sc in Sr 2 RuO 4 and d-wave sc in CeCoIn 5 and κ-(ET)2Cu(NCS)2 respectively. More recently it is shown that ∆(k) in both YNi2B2C and PrOs4Sb12 have point nodes described by hybrid s+g wave gap function.

Quasiparticle transport in vortex state of borocarbides YNi2B2C

“…Then the quasiparticle density of states and k zz of A phase is practically the same as in YNi 2 B 2 C: For B phase, on the other hand both of them are proportional to ð1 À sin 2 y sin 2 fÞ 1=2 : These angular dependencies are consistent with data from PrOs 4 Sb 12 [7]. Also as in YN π /4 π /2 3 π /4 π ϕ θ = π /4 θ = π /3 θ = π /2 I(θ,ϕ) …”

Evolution of nodal superconductivity in borocarbides YNi2B2C with impurity scattering

“…Also solving Eq. (4) for G=D > 1; we can show DðT; GÞ obeys the same gap equation as the one for s-wave superconductor with the transition temperature T c : More details have been reported elsewhere [10][11][12]. …”

Quasiparticle spectrum of the hybrids+g-wave superconductorsYNi2B

“…12 Theoretical studies of nonmagnetic impurity scattering in anisotropic superconductors indicate that this type of disorder has much more profound effects on the hybrid sϩg-wave superconductors with point nodes than on other unconventional superconductors with line nodes. 13,14 In particular, it was observed that the unitary limit and the weakscattering Born limit give practically the same results over a wide range of parameters. Also, contrary to superconductors with line nodes, no low-frequency resonance is found for the strong-scattering case.…”

“…This dependence is well approximated by g ϭ⌫/(1ϩ2⌫/⌬). 13,14 Typical quasiparticle densities of states for the pure sϩg-wave system and in the presence of impurity scattering are shown in Fig. 1͑b͒.…”