Power-law dependence of the ab-plane penetration depth in Nd1.85Ce0.15CuO4-y

It is shown that measurements of the low-temperature nb-plane penetration depth, lambda(ab)(T), of the electron-doped superconductor Nd1.85Ce0.15CuO4-y may be affected by the paramagnetism arising from the Nd3+ ions. Making a correction based on the static susceptibility measured for single crystals alters the limiting temperature dependence of lambda(ab)(T)-lambda(ab)(0) 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.