Almeida Trevor P, Temple Rowan, Massey Jamie, Fallon Kayla, McGrouther Damien, Moore Thomas, Marrows Christopher H, McVitie Stephen
SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK.
School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.
Sci Rep. 2017 Dec 19;7(1):17835. doi: 10.1038/s41598-017-18194-0.
Equi-atomic FeRh is a very interesting material as it undergoes a magnetostructural transition from an antiferromagnetic (AF) to a ferromagnetic (FM) phase between 75-105 °C. Its ability to present phase co-existence separated by domain walls (DWs) above room temperature provides immense potential for exploitation of their DW motion in spintronic devices. To be able to effectively control the DWs associated with AF/FM coexistence in FeRh thin films we must fully understand the magnetostructural transition and thermomagnetic behaviour of DWs at a localised scale. Here we present a transmission electron microscopy investigation of the transition in planar FeRh thin-film samples by combining differential phase contrast (DPC) magnetic imaging with in situ heating. We perform quantitative measurements from individual DWs as a function of temperature, showing that FeRh on NiAl exhibits thermomagnetic behaviour consistent with the transition from AF to FM. DPC imaging of an FeRh sample with HF-etched substrate reveals a state of AF/FM co-existence and shows the transition from AF to FM regions proceeds via nucleation of small vortex structures, which then grow by combining with newly nucleated vortex states into larger complex magnetic domains, until it is in a fully-FM state.
等原子比的FeRh是一种非常有趣的材料，因为它在75 - 105°C之间会经历从反铁磁（AF）到铁磁（FM）相的磁结构转变。它在室温以上呈现由畴壁（DWs）分隔的相共存的能力，为在自旋电子器件中利用其DW运动提供了巨大潜力。为了能够有效控制FeRh薄膜中与AF/FM共存相关的DWs，我们必须在局部尺度上充分理解DWs的磁结构转变和热磁行为。在此，我们通过将差分相衬（DPC）磁成像与原位加热相结合，对平面FeRh薄膜样品中的转变进行了透射电子显微镜研究。我们对单个DWs进行了作为温度函数的定量测量，结果表明NiAl上的FeRh表现出与从AF到FM转变一致的热磁行为。对具有HF蚀刻衬底的FeRh样品进行DPC成像，揭示了AF/FM共存状态，并表明从AF区域到FM区域的转变是通过小涡旋结构的成核进行的，这些小涡旋结构随后通过与新成核的涡旋状态合并形成更大的复杂磁畴而生长，直到处于完全FM状态。
