Cluster glass magnetism in the phase-separated Nd_2/3Ca_1/3MnO₃ perovskite

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• 作者：Elena Fertman ; Sergiy Dolya ; Vladimir Desnenko ; Anatoly Beznosov ; Marcela Kaj¨¾akov¨¢ ; Alex ; er Feher
• 关键词：Cluster glass ; Phase separation ; Static magnetization ; Dynamic magnetization ; Relaxation
• 刊名：Journal of Magnetism and Magnetic Materials
• 出版年：2012
• 出版时间：September, 2012
• 年：2012
• 卷：324
• 期：19
• 页码：3213-3217
• 全文大小：537 K

文摘

A detailed study of the low-temperature magnetic state and the relaxation in the phase-separated colossal magnetoresistance Nd_2/3Ca_1/3MnO₃ perovskite has been carried out. Clear experimental evidence of the cluster-glass magnetic behavior of this compound has been revealed. Well defined maxima in the in-phase linear ac susceptibility ¦Ö¡ä(T) were observed, indicative of the magnetic glass transition at T_g¡«60 K. Strongly divergent zero-field-cooled and field-cooled static magnetizations and frequency dependent ac susceptibility are evident of the glassy-like magnetic state of the compound at low temperatures. The frequency dependence of the cusp temperature T_max of the ¦Ö¡ä(T) susceptibility was found to follow the critical slowing down mechanism. The Cole-Cole analysis of the dynamic susceptibility at low temperature has shown extremely broad distribution of relaxation times, indicating that spins are frozen at ¡°macroscopic¡± time scale. Slow relaxation in the zero-field-cooled magnetization has been experimentally revealed. The obtained results do not agree with a canonical spin-glass state and indicate a cluster glass magnetic state of the compound below T_g, associated with its antiferromagnetic-ferromagnetic nano-phase segregated state. It was found that the relaxation mechanisms below the cluster glass freezing temperature T_g and above it are strongly different. Magnetic field up to about ¦Ì₀H¡«0.4 T suppresses the glassy magnetic state of the compound.