A DYNAMIC STUDY OF SMALL INTERACTING PARTICLES - SUPERPARAMAGNETIC MODEL AND SPIN-GLASS LAWS
A DYNAMIC STUDY OF SMALL INTERACTING PARTICLES - SUPERPARAMAGNETIC MODEL AND SPIN-GLASS LAWS
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DOI：
10.1088/0022-3719/21/10/019
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发表时间：
1988-04-10
期刊：
影响因子：
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通讯作者：
FIORANI, D
中科院分区：
文献类型：
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作者：
DORMANN, JL;BESSAIS, L;FIORANI, D
用低频交流磁化率测量方法研究了由相互作用的小颗粒（分散在无定形氧化铝基体中的铁颗粒）组成的系统的动力学性质。已发现同相磁化率chi '（在T B）和异相磁化率chi”的最大值。在大的频率范围内分析了T B的频率依赖性，包括以前的交流磁化率测量结果（17< or= nu< or= 10 4 Hz）和穆斯堡尔谱。结果进行了比较：（一）从超顺磁模型的预测，它考虑到磁相互作用的弛豫时间的影响，和（ii）提出的动态标度律自旋玻璃（富尔彻定律，广义阿罗修斯定律（在Tc = 0过渡）和幂律（在Tc不= 0过渡））。这些结果与有限温度下的相变是不相容的。作者提出的超顺磁模型，包括粒子间的相互作用，这意味着在0 K的温度下的转变是令人满意的解释。
The dynamic properties of a system constituted by small interacting particles (iron grains dispersed in an amorphous alumina matrix) have been studied by AC susceptibility measurements at low frequency (nu= 2* 10-2 and 2* 10-3 Hz). Maxima have been found for the in-phase susceptibility chi'(at T B) and for the out-of-phase susceptibility chi". The frequency dependence of T B is analysed over a large frequency range, including previous results from AC susceptibility measurements (17< or= nu< or= 10 4 Hz) and Mossbauer spectroscopy. The results are compared with (i) the predictions from a superparamagnetic model, which takes into account the effect of magnetic interactions on the relaxation time, and (ii) the dynamic scaling laws proposed for spin glasses (the Fulcher law, the generalised Arrhenius law (transition at T c= 0) and the power law (transition at T c not= 0)). The results are not compatible with a transition at a finite temperature. They are satisfactorily explained by the authors superparamagnetic model, including inter-particle interactions, which implies a transition at a temperature of 0 K.