Reentrant spin glass behavior in polycrystalline La0.7Sr0.3Mn1-XFeXO 3
Reentrant spin glass behavior in polycrystalline La0.7Sr0.3Mn1-XFeXO 3
复制标题
多晶 La0.7Sr0.3Mn1-XFeXO 3 中的重入自旋玻璃行为
DOI：
10.1590/s1516-14392004000200023
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发表时间：
2004
影响因子：
1.7
通讯作者：
A. A. Coelho
中科院分区：
文献类型：
--
作者：
M. Xavier;F. Cabral;J. H. Araújo;T. Dumelow;A. A. Coelho
用电阻率、交流磁化率和直流磁化强度等方法研究了化合物La0.7Sr0.3Mn1-xFexO3(0.1<；x<；0.4)的磁性和输运性质。在低浓度下(x<；0.1)，随着温度的降低，体系基本上表现出类铁磁转变，尽管在先前的研究中观察到在略低于TC的温度下磁矩下降。用双交换理论解释了这种铁磁性，即在体系中形成了Mn+3/Mn+4离子对。当浓度在0.1<；x<；0.4时，体系更为复杂。Fe掺杂的增加不仅削弱了样品的铁磁有序，提高了样品的电阻率，而且在低温(T<；60K)下诱导了重入自旋玻璃相的出现。用零场冷却和场冷却测量的磁化强度是不可逆的。此外，交流敏感峰的位置随频率而变化。所有这些效应都是自旋玻璃行为的特征。这一结果的解释是由于Fe团簇边界上的Fm-Mn+3/Mn+4相互作用和离子间的反铁磁相互作用之间的竞争加剧而导致的受挫程度增加。
The magnetic and transport properties of the compound La0.7Sr0.3Mn1-xFexO 3 (0.1 < x <0.4) have been studied by means of electrical resistivity, AC magnetic susceptibility, and DC magnetization. At low concentrations (x <0.1), the system displays essentially para-to-ferromagnetic transitions as the temperature is decreased, although a decrease in the magnetic moment has been observed in previous studies at temperatures a little below TC. This ferromagnetism is explained by double exchange theory in terms of the formation of Mn+3/Mn+4 ions pairs in the system. At concentrations in the range 0.1 < x <0.4 the system is more complex. Increased Fe doping not only weakens the ferromagnetic (FM) order and augments the resistivity of the samples, but also induces the appearance of a reentrant spin glass phase at low temperatures (T < 60 K). Irreversibility of the magnetization measured with zero field cooling and with field cooling has been observed. In addition, the AC susceptibility peak position varies with frequency. All these effects are characteristic of spin glass behavior. The results have been interpreted based in an increase of frustration due to increasing competition between FM Mn+3/Mn+4 interactions and antiferromagnetic interactions between ions at the boundaries of Fe clusters.