Metal-Insulator Transition and Low Temperature Phase Diagram for the (Nd1-xGdx)1.85Ce0.15CuO4-δ System

H. C. Ku；J. H. Shieh；G. H. Hwang

Chinese Journal of Physics

30卷2期（1992 / 04 / 01）

197 - 205

英文

A metal-insulator transition and a low temperature phase diagram for the (Nd1-xGdx)1.85Ce0.15CuO4-δ system are reported. Superconductivity appears only in the metallic region, while a metal-insulator transition for x ＞ 0.65 occurs in this oxygen-reduced system. The superconducting transition temperature Tc decreases from 24-31 K for x = 0.0 to 15 K for x = 0.5, and no transition is observed above 2 K for x = 0.65. In the insulator region (x ＞ 0.65), complex magnetic structures with weak ferromagnetic (canted antiferromagnetic) Curie temperature Tc of the Cu spins prevail at around 130-162 K. Cu-spin reorientation and rare earth (Gd/Nd) antiferromagnetic ordering were observed at lower temperatures (＜ 15 K).