Power-law dependence of the $\mathrm{ab}$-plane penetration depth in ${\mathrm{Nd}}_{1.85}{\mathrm{Ce}}_{0.15}\mathrm{Cu}{\mathrm{O}}_{4-y}$

It is shown that measurements of the low-temperature $\mathrm{ab}$-plane penetration depth, ${\lambda }_{\mathrm{ab}}\mathrm{}\left(T\right)\mathrm{}$, of the electron-doped superconductor ${\mathrm{Nd}}_{1.85}{\mathrm{Ce}}_{0.15}\mathrm{Cu}{\mathrm{O}}_{4-y}$ may be affected by the paramagnetism arising from the ${\mathrm{Nd}}^{3+}$ ions. Making a correction based on the static susceptibility measured for single crystals alters the limiting temperature dependence of ${\lambda }_{\mathrm{ab}}\mathrm{}\left(T\right)-{\lambda }_{\mathrm{ab}}\mathrm{}\left(0\right)\mathrm{}$ from an exponential behavior, typical of $s$-wave pairing, to a $T^1$ or $T^2$ behavior associated with $d$-wave pairing. It is argued that this correction is probably still appropriate at microwave frequencies. Thus the widely held belief that the electron-doped cuprate superconductors are $s$ wave is still not established and further experiments are proposed.