Temperature Dependence of Penetration Depth and Surface Resistance of ${\mathrm{Nd}}_{1.85}$${\mathrm{Ce}}_{0.15}$${\mathrm{CuO}}_4$

The temperature dependence of the in-plane penetration depth ${\lambda }_{\mathrm{\parallel }}$ and surface resistance ${\mathrm{R}}_{\mathrm{s}}$ at 9.6 GHz were measured for high-quality ${\mathrm{Nd}}_{1.85}$${\mathrm{Ce}}_{0.15}$${\mathrm{CuO}}_4$ thin films and single crystals. Both${\lambda }_{\mathrm{\parallel }}$(T) and ${\mathrm{R}}_{\mathrm{s}}$(T) are well described within the BCS framework over the entire temperature range ${\mathrm{belowT}}_{\mathrm{c}}$, yielding an energy gap ratio 2Δ/${\mathrm{k}}_{\mathrm{B}}$${\mathrm{T}}_{\mathrm{c}}$=4.1±0.2 and the London penetration depth${\lambda }_{\mathrm{L}\mathrm{\parallel }}$(0)∼1000 Å. These results indicate that the electrodynamics of this n-type cuprate superconductor are consistent with a single-gaps-wave BCS behavior. © 1993 The American Physical Society