Current-induced motion of antiskyrmions in Heusler thin films

磁天子和反天子是受拓扑保护的手性磁性纳米物体，是未来高密度、高能效的跑道存储器件的潜在信息载体。在第一轮SPP中，我们利用Lorentz电子显微镜和磁力显微镜，展示了反天子的厚度无关的内在稳定性，反天子大小的稳健可调性，以及由于长距离双极-偶极相互作用而使椭圆布洛赫天子稳定的现象。到目前为止，我们还没有发现利用大块晶体形成的片层中的体积自旋转移力矩来证明反天子运动的证据。我们目前的计划集中在生长超薄的外延Heusler薄膜，这种薄膜可以支撑天子，我们可以用它来制备磁道，主要目的是展示利用邻近金属层的自旋轨道扭矩来实现电流诱导的反天子操纵。为了实现这一目标，我们将探索使用新型化学模板层(CTL)生长超薄Heusler薄膜。后者已被用来形成二元四方化合物，即使在室温下沉积，这些化合物也是化学有序的。CTL方法使用具有CsCL结构的化合物，如煤、乙醛和该家族的其他成员(作为底层)，这些化合物是原子有序的。我们最初的重点将是在更厚的D2D Heusler薄膜中稳定单个反天子。我们的下一个重点将是演示只有一两个单位电池厚的超薄膜中反天子的形成，并探索反天子在自旋轨道扭矩下的运动。一个重要的目标将是生长基于Heusler的合成反铁磁(SAF)结构，其中两个垂直磁化的铁磁Heusler子层通过超薄金属鲁尔间隔层介导的反铁磁层间交换作用耦合。与铁磁材料中的反天子一样，SAF中的耦合反天子完全不受Kyrmion Hall效应的影响。为了生长这些薄膜，磁控共溅射以及低气压，将使用最近在MPI-Halle设计和建造的具有三个源和多个靶的离子束溅射能力。变温LTEM、MFM、STXM和克尔显微镜等多种磁成像技术将被用来研究电流诱导的运动。

Magnetic skyrmions and antiskyrmions are topologically protectedchiral magnetic nano-objects, which are potential information carriersfor future dense and energy-efficient racetrack memory devices. Inthe first round of this SPP, by employing Lorentz transmission electronmicroscopy (LTEM) and magnetic force microscopy (MFM), weshowed the thickness-independent intrinsic stability of antiskyrmions,robust tunability of the size of antiskyrmions and stabilization ofelliptical Bloch skyrmions in the antiskyrmions system due to longrangedipole-dipole interactions. To date, we have found no evidencefor the motion of antiskyrmions using volume spin transfer torques inlamellae formed from bulk crystals. Our current proposal focuses onthe growth of ultra-thin epitaxial Heusler films that could hostantiskyrmions and from which we can prepare magnetic racetrackswith the principle objective of demonstrating the current-inducedmanipulation of antiskyrmions using spin-orbit torques from adjacentheavy metal layers. To achieve this objective we will explore thegrowth of ultra-thin Heusler films using novel chemical templatinglayers (CTL). The latter have been used to form binary tetragonalcompounds, which are chemically ordered even for room temperaturedeposition. The CTL method uses compounds such as CoAl, IrAl andother members of this family (as an underlayer) with the CsClstructure that are atomically ordered. Our initial focus will be tostabilize individual antiskyrmions in thicker D2d Heusler films. Ournext focus will be to demonstrate the formation of antiskyrmions inultra-thin films, just one or two unit cells thick and exploring the motionof antiskyrmions under spin orbit torques. An important objective willbe to grow Heusler-based synthetic antiferromagnetic (SAF)structures, where two perpendicularly magnetized ferromagneticHeusler sub-layers are coupled via antiferromagnetic interlayerexchange interaction mediated by ultrathin metallic RuAl spacer layer.Unlike antiskyrmions in ferromagnetic materials, coupledantiskyrmions in SAFs are completely free from the influence of theskyrmion Hall effect. To grow these films magnetron co-sputtering, aswell as a low pressure, ion beam sputtering capability with threesources and multiple targets will be employed that has recently beendesigned and built at the MPI-Halle. A combination of variousmagnetic imaging techniques including variable temperatures LTEM,MFM, STXM and Kerr microscopy will be used to study the currentinducedmotion.