Magnetic stray fields in nanoscale magnetic tunnel junctions
Magnetic stray fields in nanoscale magnetic tunnel junctions
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DOI：
10.1088/1361-6463/ab4fbf
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发表时间：
2020-01-23
影响因子：
3.4
通讯作者：
Evans, Richard F. L.
中科院分区：
文献类型：
--
作者：
Jenkins, Sarah;Meo, Andrea;Evans, Richard F. L.
磁杂散场是铁磁器件和传感器不可避免的结果，导致磁特性的自然不对称性。这种不对称性对于其中自由层（FL）可能呈现偏置的磁性随机存取存储器应用是特别不期望的。使用原子偶极子？偶极子计算我们数值模拟从具有不同几何形状的磁存储器件的磁层发出的杂散磁场。我们发现，边缘效应占主导地位的整体杂散磁场在图案化的设备和传统的合成反铁磁结构只能部分地补偿在FL位置的字段。颗粒参考层被认为提供近场通量闭合，而额外的图案化缺陷增加了纳米级器件中杂散场的显著复杂性。最后，我们发现，从纳米反铁磁体的杂散场是令人惊讶的非零所产生的不完善的抵消磁性亚晶格由于边缘缺陷。我们的研究结果提供了一个轮廓的作用，不同的层结构和缺陷的有效杂散磁场在纳米级磁性随机存取存储器设备，并表明原子计算提供了一个有用的工具来研究杂散场效应所产生的各种缺陷。
The magnetic stray field is an unavoidable consequence of ferromagnetic devices and sensors leading to a natural asymmetry in magnetic properties. Such asymmetry is particularly undesirable for magnetic random access memory applications where the free layer (FL) can exhibit bias. Using atomistic dipole?dipole calculations we numerically simulate the stray magnetic field emanating from the magnetic layers of a magnetic memory device with different geometries. We find that edge effects dominate the overall stray magnetic field in patterned devices and that a conventional synthetic antiferromagnet structure is only partially able to compensate the field at the FL position. A granular reference layer is seen to provide near-field flux closure while additional patterning defects add significant complexity to the stray field in nanoscale devices. Finally we find that the stray field from a nanoscale antiferromagnet is surprisingly non-zero arising from the imperfect cancellation of magnetic sublattices due to edge defects. Our findings provide an outline of the role of different layer structures and defects in the effective stray magnetic field in nanoscale magnetic random access memory devices and demonstrate that atomistic calculations provide a useful tool to study the stray field effects arising from a wide range of defects.