Antiferromagnetic Skyrmions in ultra-thin oxide films

反铁磁skyrmions是未来自旋电子应用的有希望的候选者，因为它们结合了反铁磁体的优点，如消失的磁失散场和快速动力学，以及粒子状skyrmions的独特性质。许多不同的材料表现出反铁磁相互作用，因此可能潜在地承载反铁磁天子。一些理论研究强调，与普通的（铁磁的）天幕子偏转相反，这种反铁磁的天幕子预计会完全沿着横向电流的方向运动。虽然最近已经报道了合成反铁磁体中的skyrmions，即反平行耦合铁磁层，以及铁磁体中的skyrmions，但尚未提出反铁磁材料中单个skyrmions的实验证明。孤立的反铁磁天子总是亚稳的物体。为了在反铁磁体中稳定这种局域扭曲自旋织构，相关磁相互作用之间需要有利的相互作用。与铁磁斯基米子相反，它们的反铁磁对应物不能被外磁场诱导，因此必须实现反铁磁态和亚稳态反铁磁斯基米子之间的局部操纵。我们已经确定了超薄磁性氧化膜的材料类别，在稳定和操纵反铁磁粒子方面都有前景。根据制备条件的不同，可以将不同数量的氧掺入磁性薄膜的表层，从而实现磁性的调整，从而实现反铁磁粒子稳定的有利相互作用。许多超薄磁性氧化膜是极性的，因此它们本质上放大了局部电场对自旋织构的影响，从而促进了磁态的局部操纵。我们将在低温下使用自旋极化扫描隧道显微镜来表征模型型超薄氧化膜的磁序。这种实验方法特别适合于研究原子尺度的磁态，因为它结合了自旋灵敏度和原子分辨率。此外，探针尖端将用于局部产生和湮灭具有垂直电流或电场的粒子状反铁磁天空子。

Antiferromagnetic skyrmions are promising candidates for future spintronic applications because they combine advantages of antiferromagnets, such as a vanishing magnetic strayfield and fast dynamics, with the unique properties of particle-like skyrmions. Many different materials exhibit antiferromagnetic interactions and thus may potentially host antiferromagnetic skyrmions. Several theoretical studies have highlighted that such antiferromagnetic skyrmions are expected to exhibit a motion exactly along the direction of lateral currents, in contrast to ordinary (ferromagnetic) skyrmions which are deflected. Whereas recently skyrmions in synthetic antiferromagnets, i.e. antiparallelly coupled ferromagnetic layers, and skyrmions within ferrimagnets have been reported, no experimental demonstration of an individual skyrmion in an antiferromagnetic material has yet been presented. Isolated antiferromagnetic skyrmions are always metastable objects. To stabilize such localized twisted spin textures in antiferromagnets, a favorable interplay between the relevant magnetic interactions is necessary. In contrast to ferromagnetic skyrmions their antiferromagnetic counterparts cannot be induced by external magnetic fields, thus a local manipulation between an antiferromagnetic state and the metastable antiferromagnetic skyrmion must be achieved.We have identified the material class of ultra-thin magnetic oxide films as promising for both the stabilization and the manipulation of antiferromagnetic skyrmions. Depending on the preparation conditions variable amounts of oxygen can be incorporated into the surface layers of a magnetic film, enabling a tuning of the magnetic properties in order to achieve a favorable interplay for the stabilization of antiferromagnetic skyrmions. Many ultra-thin magnetic oxide films are polar, and thus they intrinsically amplify the effect of local electric fields on the spin texture, facilitating the local manipulation of the magnetic state. We will use spin-polarized scanning tunneling microscopy at low temperatures to characterize the magnetic order of model-type ultra-thin oxide films. This experimental method is particularly suited to study atomic-scale magnetic states because it combines spin sensitivity with atomic resolution. Moreover, the probe tip will be used to locally create and annihilate particle-like antiferromagnetic skyrmions with vertical currents or electric fields.