Critical size for exchange bias in ferromagnetic-antiferromagnetic particles
Critical size for exchange bias in ferromagnetic-antiferromagnetic particles
复制标题
DOI：
10.1063/1.1978977
复制
发表时间：
2005-07-04
影响因子：
4
通讯作者：
Van Tendeloo, G
中科院分区：
文献类型：
--
作者：
Dobrynin, AN;Ievlev, DN;Van Tendeloo, G
我们研究了平均晶粒尺寸为3nm的氧化Co纳米颗粒嵌入无定形Al2O3基体中的磁性能。这些纳米颗粒可以被认为是不完美的Co-core co -shell体系。磁场冷却后的磁化测量显示磁滞回线有垂直位移，而没有观察到交换偏置。通过一个简单的模型，我们证明了铁磁-反铁磁混合粒子存在一个临界晶粒尺寸，低于此尺寸，铁磁和反铁磁成分的任何比例都不存在交换偏置。其原因是由于纳米颗粒具有较大的表面体积比，界面交换能在体系中占主导地位。(c) 2005年美国物理研究所。
We present a study of the magnetic properties of oxidized Co nanoparticles with an average grain size of 3 nm, embedded in an amorphous Al2O3 matrix. These nanoparticles can be considered as imperfect Co-core CoO-shell systems. Magnetization measurements after magnetic field cooling show a vertical shift of the hysteresis loop, while no exchange bias is observed. With a simple model, we show that there is a critical grain size for hybrid ferromagnetic-antiferromagnetic particles, below which exchange bias is absent for any ratio of ferromagnetic and antiferromagnetic constituents. The reason is that the interfacial exchange energy dominates over other energies in the system due to a large surface-to-volume ratio in the nanoparticles. (c) 2005 American Institute of Physics.