Glassy dynamics in the exchange bias properties of the iron/iron oxide nanogranular system

被引：32
作者：
Fiorani, D [1 ]
Del Bianco, L
Testa, AM
Trohidou, KN
机构：
[1] CNR, Ist Struttura Mat, I-00016 Rome, Italy
[2] Univ Bologna, Dipartimento Fis, I-40127 Bologna, Italy
[3] CNR, INFM, I-40127 Bologna, Italy
[4] NCSR Demokritos, Inst Sci Mat, Athens 15310, Greece
来源：
PHYSICAL REVIEW B | 2006年 / 73卷 / 09期
关键词：
D O I：
10.1103/PhysRevB.73.092403
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
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 t(w) spent at T=50 K, after applying the cooling field. During t(w), 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.
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