Magnetic phase diagram of Nd_(0.5)Ca_(0.5-y)Sr_yMnO_3

摘要

The phase diagram obtained for Nd_(0.5)Ca_(0.5-y)Sr_yMnO_3 from the temperature dependent magnetization and electron spin resonance measurements are presented in this paper. It is found from magnetization measurements that y=0.25 is a critical point where a magnetic transformation occurs, accompanied by a nonmonotonic variation in the c lattice parameter. Below a certain transition temperature, compounds with y< 0.25 exhibit charge ordering and those with y ≥0.25 show ferromagnetic ordering. An antiferromagnetic transition occurs for y=0 at still lower temperatures whereas a phase separation into antiferromagnetically and ferromagnetically ordered states occurs for 0 < y ≤ 0.5. Electron spin resonance analysis shows that the phase separation occurs at temperatures above the ferromagnetic transition temperature in all the compounds with y >0.