Topological Nernst effect of individual skyrmions

Skyrmions是磁性材料中由于对称和反对称交换相互作用的竞争而产生的纳米级涡旋拓扑自旋结构。虽然电检测和skyrmions的操作已经在过去的几年里进行了大量的研究，但skyrmions系统的热电特性仍然处于起步阶段。最近，在自己的前期工作中，首次测量了单个天空的热电信号。然而，尽管skyrmions具有拓扑性质，但在实验数据中没有令人信服的证据表明拓扑能斯特效应的存在。因此，该项目的目标是首次通过实验测量和表征各种材料系统中单个skyrmions的拓扑能量贡献。为了实现这一目标，skyrmionic薄膜将被制成微型和纳米器件，并进行热电表征。磁力显微镜和其他成像技术将被用于确定和控制设备中skyrmions的数量。在此基础上，将得出正在研究的天幕的确切数量、大小和磁性结构的细节，并确定与预期的异常能斯特效应的偏差。此外，成像将允许寻找由热梯度引起的skyrmion运动的证据，从而为热诱导扭矩提供证据。这种对skyrmiion系统和器件的热电特性以及它们对热梯度响应的研究不仅可以深入了解拓扑保护自旋系统中耦合热、电荷和自旋电流的基本物理，而且还可能为单个skyrmions的检测和热诱导操作提供新的工具。

Skyrmions are nano scale vortex like topological spin structures which can appear in magnetic materials due to competition of symmetric and antisymmetric exchange interaction. While electrical detection and manipulation of skyrmions has been heavily investigated over the last years the thermoelectrical characterization of skyrmion systems is still in its infancy. Recently, in own previous work the thermoelectrical signal of single skyrmions has been measured for the first time. However, despite the topological nature of the skyrmions no convincing evidence for the presence of a topological Nernst effect was present in the experimental data. Therefore, the goal of this project is to experimentally measure and characterize for the first time the topological Nernst contributions of individual skyrmions in a variety of material systems. To achieve this, skyrmionic thin films will be patterned into micro and nano devices and thermoelectrically characterized. Magnetic force microscopy and other imaging techniques will be used to determine and manipulate the number of skyrmions in the devices in-situ. Based on that the exact number, sizes, and details of the magnetic structure of the skyrmions under investigation will be derived and deviations from the expected anomalous Nernst effect will be pinpointed. Additionally, the imaging will allow to seek evidence for skyrmion motion induced by thermal gradients and hence for thermally induced torques. Such thermoelectrical characterization of skyrmion systems and devices and the study of their response to thermal gradients could not only enable a deep insight into the fundamental physics of coupled heat-, charge-, and spin-currents in topologically protected spin systems but might also provide new tools for the detection and thermally induced manipulation of individual skyrmions.