Synthetic Antiferromagnetic Skyrmions

在这个项目中，我们将稳定在手性合成反铁磁多层膜中称为skyrmions的小圆形磁畴，并研究它们的电流驱动动力学。该项目基于我们团队最近的两项突破：我们能够稳定Skyrmions作为一个拓扑保护结构（使它们抗湮灭）在适当设计的单个手性垂直磁化层中，并且能够移动耦合的拓扑缺陷（畴壁）在低电流密度下，在一个简单的，虽然常规Skyrmions是提供非常低功率操作的前景的各种新颖信息存储和处理装置的令人感兴趣的候选者，由于拓扑阻尼，它们预期在小尺寸下缓慢移动，并且通过导致Skyrmion霍尔效应的马格努斯力以与它们的当前驱动方向成一角度转向。为了实现它们的潜力，我们需要建立最佳的多层结构，以支持合成的反铁磁skyrmions，这些skyrmions体积小，移动的，并且沿着电流驱动的方向移动。我们需要找到一种可靠的成核方法，以控制的方式合成反铁磁skyrmions为进一步的研究。我们需要知道如何通过平衡两个分量skyrmion上的马格努斯力来使合成反铁磁skyrmion直接响应于自旋电流驱动，以将skyrmion霍尔角减小到零。最后，我们需要学习如何利用拓扑阻尼的预期抑制，以使合成的反铁磁skyrmions以比传统skyrmions更高的速度和更小的尺寸移动。在这个项目中，我们将准备支持合成反铁磁skyrmion的手性磁性多层膜，图像的skyrmion结构，并制造纳米器件，我们可以测量电流驱动的skyrmion动力学。我们将联合收割机结合我们的专业知识与合成反铁磁多层膜与我们证明的能力，诱导强Dzyaloshinskiiii-Moriya相互作用的接口，联合收割机两个耦合的skyrmion与相反的极性和手性成一个合成的反铁磁skyrmion，可以在室温下稳定，与他们的结构和运动场成像使用国家的最先进的显微镜技术。接下来，我们将研究合成反铁磁skyrmions在随机发生的和故意引入的缺陷，由于应用的刺激，包括脉冲磁场或电流的成核。然后，我们将准备skyrmion赛道沿着合成反铁磁skyrmion可以使用电流驱动的扭矩从这个优化的多层堆栈和图像的skyrmion运动在中等电流密度，以测量skyrmion霍尔角，并找到当它是零的条件。我们将继续增加电流密度，以寻求高速skyrmion运动利用抑制拓扑阻尼之间产生的耦合拓扑缺陷在合成反铁磁体。我们将获得的结果不仅会导致高影响力的出版物和会议演示，通过阐明这种新的材料组合提供的可能性，而且还开发了基于合成反铁磁skyrmions的自旋电子学领域的潜在有价值的专有技术用于技术应用。

In this project we will stabilise small circular magnetic domains called skyrmions in chiral synthetic antiferromagnetic multilayers and study their current-driven dynamics. The project is based on two recent breakthroughs by our groups: our being able to stabilise skyrmions as a topologically protected structure (making them resistant to annihilation) in a suitably designed single chiral perpendicularly magnetised layer, and being able to move coupled topological defects (domain walls) at low current density in a simple in-plane magnetised synthetic antiferromagnet.Whilst conventional skyrmions are interesting candidates for a variety of novel information storage and processing devices that offer the prospect of very low power operation, they are expected to move slowly at small sizes due to topological damping and are diverted at an angle to their current drive direction by the Magnus forces that lead to a skyrmion Hall effect. To realise their potential, we need to establish the optimal multilayer structure to support synthetic antiferromagnetic skyrmions that are small, highly mobile, and move in the direction of an electrical current drive. We need to find a reliable nucleation method to that can create synthetic antiferromagnetic skyrmions in a controlled manner for further study. We need to know how make synthetic antiferromagnetic skyrmions respond directly to spin current drives by balancing the Magnus forces on the two component skyrmions to reduce the skyrmion Hall angle to zero. Finally, we need to learn how to exploit the expected suppression of topological damping in order to move the synthetic antiferromagnetic skyrmions move at velocities far higher, and at smaller sizes, than for conventional skyrmions. In this project we will prepare chiral magnetic multilayers that support synthetic antiferromagnetic skyrmions, image the skyrmion structures, and fabricate nanoscale devices in which we can measure current-driven skyrmion dynamics. We will combine our expertise with synthetic antiferromagnet multilayers with our proven ability to induce strong Dzyaloshinskii-Moriya interactions at interfaces to combine two coupled skyrmions with opposite polarity and chirality into a synthetic antiferromagnetic skyrmion that can be stabilised at room temperature, with their structure and motion under field imaged using state-of-the-art microscopy techniques. Next, we will study the nucleation of synthetic antiferromagnetic skyrmions at randomly occurring and deliberately introduced defects due to the application of stimuli including pulses of magnetic field or electrical current. We will then prepare skyrmion racetracks along which synthetic antiferromagnetic skyrmions can be propelled using current-driven torques from this optimised multilayer stack and image the skyrmion motion at moderate current densities in order to measure the skyrmion Hall angle and find the conditions when it is zero. We will go on to increase the current densities to seek high velocity skyrmion motion exploiting the suppression of topological damping that arises between coupled topological defects in synthetic antiferromagnets.The results we shall obtain will not only lead to high impact publications and conference presentations by shedding light on the possibilities offered by this novel combination of materials, but also develop potentially valuable knowhow in the field of spintronics based on synthetic antiferromagnetic skyrmions for technological applications.