Effect of Ga substitution on the superconducting properties of the electron-doped system: Nd-Ce-Cu-O

We are reporting on results of dc magnetization measurements of the new electron-doped Nd2-xCexCu1-yGayO4 superconductors. The effect of Ga3+ on Tc is similar to that of Ce4+, although the extra electron of the former comes from the Cu-O planes. For example, for x=0.12 the undoped compound (y=0) is not superconducting; but by the addition of Ga (y=0.03), the material becomes superconducting at Tc=20 K, and the Meissner fraction and the critical current density are improved compared to Nd1.85Ce0.15CuO4. The irreversibility line Tirr(H) for doped and undoped samples scales with the applied field as Hp, with p≅0.6, but for the Ga-doped sample it is pushed to higher temperatures