Spontaneous exchange bias formation driven by a structural phase transition in the antiferromagnetic material
Spontaneous exchange bias formation driven by a structural phase transition in the antiferromagnetic material
复制标题
DOI：
10.1038/nmat5030
复制
发表时间：
2018-01-01
期刊：
影响因子：
41.2
通讯作者：
Prieto, J. L.
中科院分区：
文献类型：
--
作者：
Migliorini, A.;Kuerbanjiang, B.;Prieto, J. L.
先进电子器件中的大多数磁性器件依赖于交换偏置效应，这是一种将铁磁材料和反铁磁材料耦合在一起的磁相互作用，导致铁磁磁滞回线单向位移，其量称为“交换偏置场”。设置和优化交换偏置涉及在磁场存在下通过反铁磁材料的尼尔温度冷却。在这里，我们展示了交换偏差产生的另一种过程。在IrMn/FeCo双层材料中，IrMn层在室温下发生结构相变，在传播过程中使FeCo层发生交换偏置。一旦工艺完成，IrMn层包含非常大的单晶晶粒，每个晶粒内都有很大密度的结构缺陷，这些缺陷由FeCo层促进。磁性表征表明，这些反铁磁层的结构缺陷是导致大的交换偏置场和良好的热稳定性的原因。在这种系统中建立交换偏差的机制有助于澄清这种交换相互作用的基本方面。
Most of the magnetic devices in advanced electronics rely on the exchange bias effect, a magnetic interaction that couples a ferromagnetic and an antiferromagnetic material, resulting in a unidirectional displacement of the ferromagnetic hysteresis loop by an amount called the 'exchange bias field'. Setting and optimizing exchange bias involves cooling through the Neel temperature of the antiferromagnetic material in the presence of a magnetic field. Here we demonstrate an alternative process for the generation of exchange bias. In IrMn/FeCo bilayers, a structural phase transition in the IrMn layer develops at room temperature, exchange biasing the FeCo layer as it propagates. Once the process is completed, the IrMn layer contains very large single-crystal grains, with a large density of structural defects within each grain, which are promoted by the FeCo layer. The magnetic characterization indicates that these structural defects in the antiferromagnetic layer are behind the resulting large value of the exchange bias field and its good thermal stability. This mechanism for establishing the exchange bias in such a system can contribute towards the clarification of fundamental aspects of this exchange interaction.