锰氧化物La0.7Ca0.225 Sr0.075MnO3的临界平均场临界行为

Tricritical Mean-field Critical Behavior of La0.7 Ca0.225 Sr0.075MnO3

研究了La0.7 Ca0.225 Sr0.075 MnO3在磁相变温度附近的临界行为,阿罗特图表明该样品为二级磁相变材料.利用修正的阿罗特图、Kouvel-Fisher和临界等温曲线方法确定了临界指数的值,三者结果基本一致,通过3种不同方法拟合获得的临界指数是准确且自洽的.研究结果表明:La0.7 Ca0.225 Sr0.075 MnO3的磁相互作用符合临界平均场模型所描绘的耦合方式,即一级和二级磁相变临界点磁相互作用.

The critical behavior of La0.7 Ca0.225 Sr0.075 MnO3 near the magnetic phase transition temperature was studied.Arrott diagram indicated that the sample was a secondary magnetic phase change material.The values of the critical exponent were determined by the modified Arrott plot,the Kouvel-Fisher and the critical isotherm curve method,which were basically the same.Therefore,the critical exponent obtained by three different methods of fitting was accurate and self-consistent.The results showed that the magnetic interaction of La0.7 Ca0.225 Sr0.075 MnO3 conformed to the coupling mode described by the critical average field model,the magnetic phase transition of the first-order and second-order was the critical point magnetic interaction.