Direct visualization of the magnetostructural phase transition in nanoscale FeRh thin films using differential phase contrast imaging
Direct visualization of the magnetostructural phase transition in nanoscale FeRh thin films using differential phase contrast imaging
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利用差相对比成像技术直接可视化纳米级铁氢薄膜的磁结构相变
DOI：
10.1103/physrevmaterials.4.034410
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发表时间：
2020-03-24
影响因子：
3.4
通讯作者：
McVitie, Stephen
中科院分区：
文献类型：
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作者：
Almeida, Trevor P.;McGrouther, Damien;McVitie, Stephen
为了推进热激活磁性材料在器件应用中的使用，有必要研究它们在局部尺度操作条件下的行为。等原子的FeRh在室温（类似于350 - 380 K）以上经历从反铁磁（AF）到铁磁（FM）相的磁结构转变，因此被认为是下一代纳米磁性或自旋电子器件的非常理想的材料。为了实现这一点，我们必须充分了解AF到FM过渡的复杂细节以及相关的FM畴在其操作规模上的生长。在这里，我们结合联合收割机原位加热与一套全面的先进的透射电子显微镜技术，直接调查纳米FeRh薄膜的磁结构转变。微分相衬成像可视化的FM域生长在横截面和平面FeRh薄膜作为温度的函数的阶段。小的表面FM信号也被检测到，由于界面应变与MgO基板和Fe不足HF蚀刻后的基板，提供了FM域生长的方向性偏置。我们的工作在整个过渡过程中提供了高分辨率成像和定量测量，这在以前是无法实现的，并为它们在磁性设备中的潜在用途提供了基本的见解。
To advance the use of thermally activated magnetic materials in device applications it is necessary to examine their behavior on the localized scale operando conditions. Equiatomic FeRh undergoes a magnetostructural transition from an antiferromagnetic (AF) to a ferromagnetic (FM) phase above room temperature (similar to 350-380 K), and hence is considered a very desirable material for the next generation of nanomagnetic or spintronic devices. For this to be realized, we must fully understand the intricate details of the AF to FM transition and associated FM domain growth on the scale of their operation. Here we combine in situ heating with a comprehensive suite of advanced transmission electron microscopy techniques to investigate directly the magnetostructural transition in nanoscale FeRh thin films. Differential phase contrast imaging visualizes the stages of FM domain growth in both cross-sectional and planar FeRh thin films as a function of temperature. Small surface FM signals are also detected due to interfacial strain with the MgO substrate and Fe deficiency after HF etching of the substrate, providing a directional bias for FM domain growth. Our work provides high resolution imaging and quantitative measurements throughout the transition, which were previously inaccessible, and offers fundamental insight into their potential use in magnetic devices.