纳米多晶La_(0.7)Sr_(0.3)MnO_3磁性相变临界行为研究  

Critical Behavior Near Ferromagnetic-paramagnetic Phase Transition in Nano-polycrystalline La_(0.7)Sr_(0.3)MnO_3

作　　者：席力[1] 乔文[1] 李明杰[1] 葛世慧[1] 

机构地区：[1]兰州大学磁学与磁性材料教育部重点实验室,兰州730000

出　　处：《材料工程》2008年第10期72-75,共4页Journal of Materials Engineering

基　　金：加拿大国际开发暑资助(CIDA);国家自然科学基金资助项目(NSFC50701021)

摘　　要：用溶胶-凝胶方法制备了纳米多晶La0.7Sr0.3MnO3样品。测量了不同温度下烧结的样品的零场冷却交流磁化率与温度和直流磁场的依赖关系。通过对铁磁-顺磁转变点附近临界峰的分析,得到973K烧结的多晶样品居里温度为312.1K±0.2K,临界指数为:δ=3.040,γ=1.007,β=0.493;1173K烧结的多晶样品居里温度为331.7K±0.1K,临界指数分别为:δ=2.950,γ=0.993,β=0.508。两组数据均与平均场理论预言结果一致,表明纳米多晶La0.7Sr0.3MnO3样品在磁性相变点附近存在长程相互作用。Nano-polycrystalline La0. 7Sr0.3MnO3 samples were fabricated by Sol-Gel method at different sintered temperatures. Field and temperature-dependent AC susceptibility has been measured in these samples. The critical peak values near their ferromagnetic-paramagnetic phase transition temperatures reveal that the curie temperature Tc = 312.1K!-0.2K and the critical exponents δ=3.040,γ=1.007,β=0.493 for the 973K sintered sample; Tc=331.7K±0.1K, δ=2.950,γ=0.993 and β=0.508 for the 1173K sintered sample, respectively. These results consist with the mean-field theory, indicating that a long-range interaction in these materials.

关 键 词：纳米多晶La0. 7Sr0.3MnO3 交流磁化率 临界指数 

分 类 号：O482.5[理学—固体物理]