Probing the order parameter of magnetically grain-aligned NCCO electron-doped cuprate

The c-axis alignment of Nd1.85Ce0.15CuO4.105 superconducting powder was achieved by applying an external magnetic field of 1 T perpendicular to the axis of rotation of powder/epoxy tetragonal holder. The temperature dependencies of the in-plane penetration depth λab and out-of-plane penetration depth λc were obtained by measuring the zero-filed-cooled ac diamagnetic susceptibility χd(T) in a low applied field (Ba = 10 Oe). An observed Nd paramagnetic background was subtracted. The relative change temperature dependence penetration depth Δλ(T) = λ(T) − λ(0) for both c-axis parallel and perpendicular to the applied field can be fitted to a quadratic d-wave rather than an exponential s-wave like function up to 0.5Tc. This result is in agreement with recent experiments suggest the unconventional nature for electron-doped RCCO (R = Pr, Nd, La, Eu, Sm) cuprates.