Effect of Bivalent Cation Ca-Doping on Magnetic Properties in?Multiferroic YMnO₃ Manganites

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• 作者：Yuling Su ; Zhenping Chen ; Yuefeng Li ; Dongmei Deng ; Shixun Cao and Jincang Zhang
• 关键词：Multiferroic ; YMnO3 ; Magnetic properties ; Charge ordering ; Spin ; glass
• 刊名：Journal of Superconductivity Incorporating Novel Magnetism
• 出版年：2010
• 出版时间：May, 2010
• 年：2010
• 卷：23
• 期：4
• 页码：501-506
• 全文大小：690.3 KB

文摘

Effect of bivalent cation Ca-doping on magnetic properties in multiferroic YMnO₃ manganites was systemically studied by DC and AC magnetic measurements. Series of samples were prepared by solid-state reaction method with composition Y_1−x Ca _x MnO₃ (x=i/8,i=2,3,…,7). The results show that each of the zero-field-cooling (ZFC) curves has a clear cusp and it shifts to higher temperature with increasing Ca-doping x. From the χ −1–T curve, the temperature of charge-ordering (CO) state T _CO is given at about 244.0 K and this indicates that the CO state is dominated by the cooperative Jahn–Teller effect in Y_1/2Ca_1/2MnO₃ with small A-site cation, for which there is a different behavior compared to the other manganites of larger 〈r _A 〉. When x=2/8 and 7/8 for Y_1−x Ca _x MnO₃, the magnetization curve shows strong irreversibility between ZFC and FC data. The variation of AC susceptibility presents a maximum cusp at the beginning temperature of the bifurcation between ZFC and ZF curve and shifts to higher temperature with increasing measurement frequency for AC susceptibility. These results can be characterized by spin-glass, indicating that much more itinerant e_g electrons are promoting the magnetic transition.