All-oxide epitaxial heterostructures for the generation and electric field control of topological spin textures

拓扑自旋结构的电场操纵是本研究的主要推动力。为了实现这一点，拓扑磁性结构必须稳定在绝缘或坏金属的材料中，例如一些钙钛矿金属氧化物。然而，定制物质物理性质的一种独特而有力的方法是设计人工结构，如外延异质结构，其中发生结构调整和界面耦合，它们与反转对称性的破坏一起强烈影响异质结构的性质，通常会产生新的性质。在我们探索的外延异质结构的特定类型中，我们的目标是利用：由于界面而产生的固有反转对称破缺，铁磁氧化层中的磁各向异性（作为磁晶各向异性和薄膜生长相关各向异性的组合），以及与具有大自旋轨道耦合的氧化物界面上的Dzyaloshinskii-Moriya相互作用（DMI）。界面DMI的大小和磁各向异性都是可调的，因此我们必须探索氧化钙钛矿层的哪些组合容易形成拓扑自旋结构。在高分辨率透射电子显微镜的原位偏置实验中，研究电场对拓扑自旋织构的控制。

Electric field-manipulation of topological spin structures is the main driving force for this proposal. In order to achieve this, topological magnetic textures have to be stabilized in materials that are insulating or bad metals, such as some perovskite metal oxides.A uniquely powerful means to tailor physical properties of matter, however, is to design artificial structures such as epitaxial heterostructures, in which structural accommodations and interfacial coupling occur, which, together with the broken inversion symmetry, strongly influence the properties of the heterostructures, often resulting in novel properties. In the particular types of epitaxial heterostructures that we explore here, we aim to make use of: inherent inversion symmetry breaking due to interfacing, magnetic anisotropy (as a combination of magneto-crystalline anisotropy and thin film growth related anisotropy) in a ferromagnetic oxide layer, and the Dzyaloshinskii-Moriya interaction (DMI) at the interface with an oxide with large spin-orbit coupling. Both the magnitude of the interfacial DMI and the magnetic anisotropy are tunable and thus we have to explore which combinations of oxide perovskite layers would be susceptible to form topological spin structures.The control of topological spin textures by electric fields will be studied in backgate electric field effects on Hall resistivity of the heterostructures and in situ biasing experiments in the high resolution transmission electron microscope.