Pajić Damir, Zadro Krešo, Ristić Ramir, Zivković Ivica, Skoko Zeljko, Babić Emil
Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, HR-10000 Zagreb, Croatia.
J Phys Condens Matter. 2007 Jul 25;19(29):296207. doi: 10.1088/0953-8984/19/29/296207. Epub 2007 Jul 5.
The magnetization processes in binary magnetic/non-magnetic amorphous alloy Hf(57)Fe(43) are investigated by the detailed measurement of magnetic hysteresis loops, temperature dependence of magnetization, relaxation of magnetization and magnetic ac susceptibility, including a nonlinear term. Blocking of magnetic moments at lower temperatures is accompanied by the slow relaxation of magnetization and magnetic hysteresis loops. All of the observed properties are explained by the superparamagnetic behaviour of the single domain magnetic clusters inside the non-magnetic host, their blocking by the anisotropy barriers and thermal fluctuation over the barriers accompanied by relaxation of magnetization. From magnetic viscosity analysis based on thermal relaxation over the anisotropy barriers it is found that magnetic clusters occupy the characteristic volume from 25 up to 200 nm(3). The validity of the superparamagnetic model of Hf(57)Fe(43) is based on the concentration of iron in the Hf(100-x)Fe(x) system that is just below the threshold for long range magnetic ordering. This work also throws more light on the magnetic behaviour of other amorphous alloys.
通过对磁滞回线、磁化强度的温度依赖性、磁化强度弛豫和包括非线性项的磁交流磁化率进行详细测量，研究了二元磁性/非磁性非晶合金Hf(57)Fe(43)中的磁化过程。较低温度下磁矩的阻塞伴随着磁化强度和磁滞回线的缓慢弛豫。所有观察到的特性都可以用非磁性基体内部单畴磁簇的超顺磁行为、它们被各向异性势垒阻塞以及势垒上的热涨落伴随着磁化强度弛豫来解释。基于各向异性势垒上的热弛豫进行磁粘滞性分析发现，磁簇占据的特征体积从25到200纳米³。Hf(57)Fe(43)超顺磁模型的有效性基于Hf(100 - x)Fe(x)体系中铁的浓度刚好低于长程磁有序的阈值。这项工作也为其他非晶合金的磁行为提供了更多的线索。
