Novel types of magnetic order generated across epitaxial interfaces of 4d and 5d transition metal perovskite oxides

该研究为在导电性差或绝缘性差的材料中制备手性磁畴提供了一个新的材料平台。例如，目前所有已知的薄膜样品中的skyrmion相都是在高导电材料中产生的。我们希望实现这样的结构，其中手性磁序稳定在氧化物之间的界面处，所述氧化物是坏金属或在以薄膜形式生长时经历金属-绝缘体转变。绝缘材料中的Skyrmion允许与金属系统中的Skyrmion不同的应用，例如绝缘手性磁体中的磁振子而不是自旋极化电流驱动的Skyrmion运动。磁数据技术领域当前的主要挑战是提高处理磁编码信息的速度和稳定性，以及开发更密集包装的数据存储概念，其优选地也是非耗散的。现今大多数磁性数据存储设备使用铁磁材料，其中磁序可以根据海森堡交换相互作用的强度来描述。在普通磁性材料中，交换相互作用导致晶格自旋的共线排列。然而，在具有破缺的反转对称性和强自旋轨道耦合的材料中，Dzyaloshinskiii-Moriya相互作用可以稳定螺旋磁序。最近发现的磁skyrmions有可能开辟一个全新的前景，以达到更高的速度和稳定性的数据记录/处理设备。Albert Fert和Peter Grünberg在磁性数据记录技术方面的革命 金属多层膜中巨磁阻效应的发现强调了异质结构对于技术进步的重要性。在过去的二十年中，具有各种物理特性的钙钛矿氧化物的外延生长已经证明自己是一种非常通用的方法，可以创造具有新物理特性的人工材料。 特别是，我们计划研究的外延界面的影响和耦合机制的异质结构相结合的4D和5D过渡金属氧化物层，如SrRuO 3和SrIrO 3。这种异质结构预计将产生非共面自旋安排在铁磁SrRuO 3薄膜和推测螺旋秩序，甚至skyrmions。目标是通过洛伦兹显微镜、电子全息术和磁输运测量来观察和研究全氧化物异质结构中的新型磁畴结构。

This research proposal provides the set-up of a new materials platform for generating chiral magnetic domains in poorly conducting or insulating materials. For example all so far known skyrmion phases in thin film samples are currently generated in highly conducting materials. We would like to realize structures in which chiral magnetic order is stabilized at interfaces between oxides that are bad metals or undergo metal-insulator transitions when grown in thin film form. Skyrmions in insulating materials allow different applications than skyrmions in metallic systems, such as skyrmion movement driven by magnon in insulating chiral magnets instead of spin-polarized currents.Major current challenges in the field of magnetic data technology are the improvement of the speed and stability of processing magnetically encoded information, and the development of even more densely-packed data storage concepts, which preferably are also non-dissipative. The majority of nowadays magnetic data storage devices uses ferromagnetic materials where the magnetic order can be described in terms of the strength of the Heisenberg exchange interaction. The exchange interaction in common magnetic materials leads to collinear alignment of lattice spins. However, in materials with broken inversion symmetry and strong spin-orbit coupling, the Dzyaloshinskii-Moriya interaction can stabilize helical magnetic order. The recent discovery of magnetic skyrmions has the potential to open up a completely new vista to reach the higher speed and stability in data recording/processing devices. The revolution made in magnetic data recording technology by Albert Fert and Peter Grünberg discovery of the giant magnetoresistance effect in metallic multilayers stresses out the importance of heterostructures for advances in technology. During the last two decades, epitaxial growth of perovskite oxides with various physical properties has proved itself as a very versatile means to create artificial materials with novel physical properties. In particular we plan to study the effects of epitaxial interfacing and the coupling mechanisms in heterostructures combining 4d and 5d transition-metal oxide layers, such as SrRuO3 and SrIrO3. This heterostructuring is expected to yield non-coplanar spin arrangements in ultrathin ferromagnetic SrRuO3 films and presumably helical order or even skyrmions. The goals are the observation and the study of novel magnetic domain structures in all-oxide heterostructures by Lorentz microscopy and electron holography and magneto-transport measurements.