Glassy dynamics in the exchange bias properties of the iron/iron oxide nanogranular system
Glassy dynamics in the exchange bias properties of the iron/iron oxide nanogranular system
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DOI：
10.1103/physrevb.73.092403
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发表时间：
2006-03
影响因子：
3.7
通讯作者：
D. Fiorani;L. Bianco;A. Testa;K. Trohidou
中科院分区：
文献类型：
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作者：
D. Fiorani;L. Bianco;A. Testa;K. Trohidou
我们观察到了由分散在结构和磁性无序的团簇玻璃状氧化铁基质中的铁纳米颗粒组成的颗粒系统中交换偏置性质的玻璃化动力学。在施加冷却场后，在T=5K下测量的交换场随着在T=50K处花费的时间tw的增加而增加。在TW过程中，氧化物相向较低的能量组态演化，导致界面交换与Fe粒子的磁矩耦合更强。在假设壳层为随机各向异性的情况下，对核壳纳米粒子的蒙特卡罗模拟再现了这种老化效应。
We have observed a glassy dynamics of the exchange bias properties in a granular system composed of Fe nanoparticles dispersed in a structurally and magnetically disordered cluster glasslike Fe oxide matrix. The exchange field, measured at T=5 K, increases with increasing the time tw spent at T=50 K, after applying the cooling field. During tw, the oxide phase evolves towards a lower energy configuration, resulting in a stronger interface exchange coupling with the Fe particle moments. Monte Carlo simulations on core/shell nanoparticles reproduce such aging effect, provided that a shell random anisotropy is assumed.