Abstract
Superconducting transition onset around 30-31 K was reported for the repeated-vacuum/Ar-annealed and liquid-nitrogen-quenched sample of the high T <sub>c</sub> electron superconductor Nd <sub>1.85</sub> Ce <sub>0.15</sub> CuO <sub>4-δ</sub> (δ = 0.07(2)). Vortex lattice melting near T <sub>c</sub> was observed for this oxygen-reduced superconductor. Low field (< 5 kG) magnetic phase diagram showed an irreversibility line (de-Almeida-Thouless line) H*(T) which was found to vary as (1-T/T <sub>c</sub> ) <sup>5/3</sup> .