The effect of Gd-doping on the charge ordering state of Bi0.3−xGdxCa0.7MnO3 (0≤x≤0.30)

The effect of Gd-doping on the charge ordering (CO) state in perovskite-type manganates Bi0.3−xGdxCa0.7MnO3 with x=0, 0.02, 0.05, 0.1, 0.3 has been investigated by transport and magnetic property measurements. It is found that CO temperature (TCO) and antiferromagnetic (AFM) ordering temperature TN occurring below TCO decrease obviously with increasing Gd-doping level. Accompanying the variation of TCO, the increased magnetization and the decreased resistivity are observed. In addition, the increased magnetic inhomogeneity has been also observed in the samples based on the difference between the zero-field-cooling (ZFC) magnetization MZFC and field-cooling (FC) magnetization MFC, which is ascribed to the competition between ferromagnetic (FM) phase induced by Gd-doping and CO AFM phase. The experimental results indicate that the Bi3+ lone pair electron with 6s2 character plays a dominating role on the CO state of Bi0.3Ca0.7MnO3.