Domain state model for exchange bias.: II.: Experiments -: art. no. 014431
Domain state model for exchange bias.: II.: Experiments -: art. no. 014431
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DOI：
10.1103/physrevb.66.014431
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发表时间：
2002-07-01
影响因子：
3.7
通讯作者：
Usadel, KD
中科院分区：
文献类型：
--
作者：
Keller, J;Miltényi, P;Usadel, KD
外延生长的Co/CoO双层的铁磁/反铁磁界面处的交换偏置耦合可以通过稀释反铁磁CoO层来有意地增强和控制，即，通过引入（i）Co取代（Co 1-xMgxO）或（ii）Co缺陷（Co 1-yO）。所有有意的缺陷或缺陷都被放置在远离界面的反铁磁层的整个体积部分。这样，Co/CoO界面处的粗糙度实际上保持相同。对于这两种类型的缺陷，交换偏置场可以增加3至4倍。因此，交换偏置主要不是由于界面处的粗糙度，而是可以由反铁磁层的体积部分中的缺陷来控制。我们系统地研究了交换偏置的各种现象的稀释依赖性，例如磁滞回线的垂直磁化位移，温度依赖性，训练效应，冷却场依赖性，和反铁磁层厚度依赖性。所有这些现象直接比较Monte Carlo模拟的结果，并显示出一致的交换偏置的域状态模型描述。结合实验和理论研究结果表明，在Co/CoO的交换偏置的起源结果从域状态的反铁磁体的体积部分的缺陷稳定。
The exchange bias coupling at ferro-/antiferromagnetic interfaces of epitaxially grown Co/CoO bilayers can be intentionally enhanced and controlled by diluting the antiferromagnetic CoO layer, i.e., by introducing (i) nonmagnetic substitutions (Co1-xMgxO) or (ii) Co deficiencies (Co1-yO). All intentional nonmagnetic cations or defects were placed away from the interface throughout the whole volume part of the antiferromagnetic layer. This way the roughness at the Co/CoO interface was kept practically the same. For both types of defects, the exchange bias field can be increased by a factor of 3 to 4. Hence, exchange bias is primarily not due to roughness at the interface but rather can be controlled by the defects in the volume part of the antiferromagnetic layer. We systematically investigate the dilution dependence of various phenomena of exchange bias, such as the vertical magnetization shift of the hysteresis loop, temperature dependence, training effect, cooling field dependence, and antiferromagnetic layer thickness dependence. All these phenomena are directly compared to results from Monte Carlo simulations and are shown to be consistently described by the domain state model for exchange bias. The combined experimental and theoretical findings suggest that the origin of exchange bias in Co/CoO results from a domain state in the volume part of the antiferromagnet stabilized by the defects.