MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China.
Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore.
ACS Appl Mater Interfaces. 2019 Feb 27;11(8):8258-8265. doi: 10.1021/acsami.8b21421. Epub 2019 Feb 12.
As a key effect in spintronic devices, exchange bias has attracted tremendous attention. Various approaches have been attempted for optimizing this effect, among which the application of strain in flexible exchange-biased systems is promising, but little significant improvement has been reported. Here, we demonstrate encouraging progress in this field. With a pure mechanical compressive strain of -6.26‰ applied to the flexible polyimide (PI) substrate, distinct enhancement of ∼900% in the bias field (from 20 to 200 Oe) is achieved for the exchange-biased (FeCo/IrMn)/Ta multilayers grown on top of a flexible PI substrate, accompanied by a notable decrease in the Gilbert damping parameter from 0.02 to 0.008, signifying an improved exchange bias effect as well as a potentially reduced switching current density. The underlying mechanism is investigated by a systematic ferromagnetic resonance study, suggesting that the angle between the unidirectional and uniaxial magnetic easy axes plays an important role, which may be controlled by adjusting the layer number. This work offers an efficient strategy for tuning the exchange bias effect via applying appropriate mechanical strain on a multiperiodic exchange bias multilayered system, opening up an avenue for tailoring the magnetic properties of flexible spintronic devices.
作为自旋电子器件中的一个关键效应，交换偏置吸引了人们极大的关注。人们尝试了各种方法来优化这种效应，其中在柔性交换偏置系统中应用应变是很有前景的，但据报道，几乎没有显著的改进。在这里，我们展示了在这一领域的令人鼓舞的进展。通过在柔性聚酰亚胺（PI）基底上施加纯机械压缩应变-6.26‰，在顶部生长的柔性 PI 基底上的（FeCo/IrMn）/Ta 多层膜的偏置场（从 20 到 200 奥斯特）得到了显著提高约 900%，同时 Gilbert 阻尼参数从 0.02 显著降低到 0.008，这表明交换偏置效应得到了改善，同时可能降低了开关电流密度。通过系统的铁磁共振研究，研究了其潜在机制，表明各向异性和单轴磁易轴之间的夹角起着重要作用，这可以通过调整层的数量来控制。这项工作通过在多层交换偏置系统上施加适当的机械应变来调整交换偏置效应提供了一种有效的策略，为灵活的自旋电子器件的磁性能的调整开辟了道路。
