Coexistence of ferromagnetic and spin-glass phenomena in La1-xCaxMnO3 (0⩽x⩽0.4)
Coexistence of ferromagnetic and spin-glass phenomena in La1-xCaxMnO3 (0⩽x⩽0.4)
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DOI：
10.1088/0953-8984/12/26/321
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发表时间：
2000-07
期刊：
影响因子：
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通讯作者：
R. Laiho;K. Lisunov;E. Lähderanta;P. Petrenko;J. Salminen;V. N. Stamov;V. Zakhvalinskii
中科院分区：
文献类型：
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作者：
R. Laiho;K. Lisunov;E. Lähderanta;P. Petrenko;J. Salminen;V. N. Stamov;V. Zakhvalinskii
研究了陶瓷 La1-xCaxMnO3 (0≤x≤0.4) 在 T = 5 和 310 K 之间的低场磁性能。在所有样品中都观察到顺磁-铁磁转变。居里温度 TC 对 x 的依赖性在与电子局域化相关的自旋极化子模型中进行了描述。当 T>TC 时，观察到磁化率 χ-1(T ) ~ (T-TC)γ 的临界行为，临界指数 γ = 1.20±0.05 和 γ* = 1.64±0.06 分别低于和高于成分 x≈0.18，对应于 Mn4+ 离子浓度 c ≈ 0.23。对于 x = 0.3 的化合物，在 0 到 8 T 之间的磁场中没有观察到电阻率的温度磁滞。在所有样品中，场冷却和零场冷却磁化强度偏离 TC，其差值大约等于热剩磁化强度 (TRM)。在 LCMO 中观察到 TRM 的长时间弛豫，时间尺度高达 104 s。弛豫率在等待时间 tW ~ 103 s 附近达到最大值。 TRM 的时间依赖性可以用拉伸指数定律来描述，就像在观察时间与 tW 相当的条件下的自旋或簇玻璃中一样。
Low-field magnetic properties of ceramic La1-xCaxMnO3 (0≤x≤0.4) are investigated between T = 5 and 310 K. The paramagnetic-ferromagnetic transition is observed in all the samples. The dependence of the Curie temperature, TC, on x is described within a model of spin polarons associated with electronic localization. Critical behaviour of the susceptibility χ-1(T ) ~ (T-TC)γ is observed for T>TC, with the critical exponents γ = 1.20±0.05 and γ* = 1.64±0.06 below and above the composition x≈0.18 corresponding to the Mn4+ ion concentration c ≈ 0.23, respectively. For the compound with x = 0.3 no temperature hysteresis of the resistivity is observed in magnetic fields between 0 and 8 T. In all the samples the field-cooled and zero-field-cooled magnetizations deviate below TC, the difference being approximately equal to the thermoremanent magnetization (TRM). Long-time relaxation of TRM in LCMO is observed for time scales up to 104 s. The relaxation rate reaches a maximum near a wait time tW ~ 103 s. The time dependence of TRM can be described with a stretched exponential law, as in spin or cluster glasses in conditions where the observation time is comparable with tW .