Phase-Sensitive Order Parameter Symmetry Test Experiments Utilizing Nd2-xCexCuO4-y/Nb Zigzag Junctions

Phase-sensitive order parameter symmetry test experiments are presented on the electron-doped high-T_c cuprate Nd_2-xCe_xCuO_4-y. These experiments have been conducted using zigzag-shaped thin film Josephson structures, in which the Nd_2-xCe_xCuO_4-y is connected to the low-T_c superconductor Nb via an Au barrier layer. For the optimally doped as well as for the overdoped Nd_2-xCe_xCuO_4-y, a clear predominant dx²_-y²-wave behavior is observed at T=4.2 K. Both compounds were also investigated at T=1.6 K, presenting no indications for a change to a predominant s-wave symmetry with decreasing temperature.