Unusual low-frequency electromagnetic response in anisotropic superconductors: Application toUPt3

Electromagnetic skin depth of unconventional superconductors

“…32 to deduce a relatively weak influence of pairbreaking on the resonant Bogoliubov quasiparticle-quasihole response described in the clean limit by (14). The microscopic calculation described here does not confirm this result.…”

“…32. We therefore concentrate on the cases of highest symmetry, lllq and I_L~, where both the coupling of the transverse wave to the density and the gauge mode contribution vanish.…”

“…As we pointed out in Ref. 32, however, in anisotropic superconductors with gap nodes the presence of a substantial population of quasiparticles at any nonzero temperature leads to the possibility of a qualitatively new dynamics through the appearance of a new low energy scale f~p.h = v~" q, the energy of Bogoliubov quasiparticle-quasihole excitations in the thermally excited quasiparticle gas near the nodes. Here fi~= (~k/Ek)Ok is the Bogoliubov quasiparticle velocity.…”

“…This effect in the clean system was referred to in Ref. 32 as "resonant Bogoliubov quasiparticle-quasihole scattering," because of the similarity of the form of the response (10c) to particle-hole scattering in a clean normal metal. The skin depth &(T) of an E~g superconductor was explicitly calculated for various frequencies in the simplest case ~ll2, A II basal plane.…”

Inductive response of polished, single crystal of UPt3

“…AC measurements, with frequencies lower than Tc (10GHz for UPt3) should give results similar to DC measurements. One expects this to hold true even for superconductors with gap nodes for temperatures such that .f,~ T,~ T~, where f is the measurement frequency (in our case f,-, 10 MHz ,-, 0.5 mK) [9]. In this context, Putikka et al [9] proposed a new energy scale :esponsible for a frequency dependence in our temperature regime.…”