Spin current transport experiments on 3-dimensional Y3Fe5O12 surfaces utilizing atomic layer deposition

钇铁石榴石（Y3 Fe 5 O 12，YIG）是一种电绝缘的亚铁磁体，有序化温度为560 K。由于极低的磁阻尼（吉尔伯特阻尼参数低至几个10 ppm）和小的矫顽场，YIG和相关的磁性石榴石现在用于各种高频应用。此外，这些材料是非常有趣的，因为它们在磁振子和自旋电子学领域的基础研究的杰出性能。然而，目前主要使用YIG单晶和平面薄膜。YIG或基于YIG的异质结构的更复杂的三维（例如弯曲或管状）薄膜结构的制造和性质尚未进行实验研究，尽管已经预测了非常有趣的性质。在本项目的框架内，我们通过建立通过原子层沉积（ALD）合成YIG层来探索这个有趣的领域。ALD基于连续的自限表面反应，因此允许任意形状表面的保形涂层。虽然（二元）氧化物薄膜的ALD已经常规地用于半导体工业中，但是必须组合两个ALD循环以产生三元化合物，例如Y3 Fe 5 O 12。因此，钇铁石榴石薄膜的成功原子层沉积也是一个有趣的技术挑战。通过结合已建立的ALD工艺，我们希望生产纳米层压材料，其中化学稳定的二元组分（Y2 O3和Fe 2 O3用于YIG）堆叠在薄膜异质结构中。在热处理之后，纳米层压材料被转化成所需的材料。首先，我们将建立Y3 Al 5 O 12（YAG）的纳米层压工艺，因为Al 2 O3 ALD特别稳健;它被认为是ALD参考工艺。之后，我们将从YAG过渡到YIG。的层的磁性能进行量化的磁力和磁共振调查。结合金属Pt的ALD工艺，YIG/Pt多层膜可以沉积在任意形状的表面上。这种异质结构对于纯自旋电流的实验是非常有趣的。在这里，我们要调查的影响，当地的曲率或拓扑结构上的自旋输运的自旋霍尔magnetoresistance experiments.In总结，所提出的原子层沉积钇铁石榴石提供了现代的基础，三维纳米结构的生产，从这种特殊的材料，因此，使大量的未来（自旋输运）的实验。

Yttrium iron garnet (Y3Fe5O12, YIG) is an electrically insulating ferrimagnet with an ordering temperature of 560 K. Due to the extremely low magnetic damping (Gilbert damping parameters down to a few 10 ppm) and the small coercive fields, YIG and related magnetic garnets are now used in various high-frequency applications. In addition, these materials are very interesting because of their outstanding properties for basic research in the field of magnonics and spin electronics. However, mostly YIG single crystals and planar thin films are currently used. The fabrication and properties of more complex, 3-dimensional (e.g. curved or tube-like) thin-film structures of YIG or YIG-based heterostructures have not been studied experimentally, although very interesting properties have been predicted.In the framework of this project, we explore this interesting field by establishing the synthesis of YIG layers by means of atomic layer deposition (ALD). ALD is based on successive, self-limited surface reactions and, thus, allows the conformal coating of arbitrarily shaped surfaces. While the ALD of (binary) oxide thin films is already routinely used in the semiconductor industry, two ALD cycles must be combined to produce ternary compounds such as Y3Fe5O12. Therefore, the successful atomic layer deposition of YIG–or more generally of garnet thin films–is also an interesting technological challenge. By combining established ALD processes, we want to produce nano-laminates in which chemically stable binary constituents (Y2O3 and Fe2O3 for YIG) are stacked in a thin-film heterostructure. After a heat treatment, the nano-laminates are converted into the desired material. First, we will establish the nano-laminate process for Y3Al5O12 (YAG), since Al2O3 ALD is particularly robust; it is considered the ALD reference process. Afterwards, we will transition from YAG to YIG. The magnetic properties of the layers are quantified by magnetometry and magnetic resonance investigations. In combination with the ALD process for metallic Pt, YIG/Pt multilayers can be deposited on arbitrarily shaped surfaces. Such heterostructures are very interesting for experiments with pure spin currents. Here, we want to investigate the influence of local curvature or topology on spin transport by means of spin-Hall magnetoresistance experiments.In summary, the proposed atomic layer deposition of yttrium iron garnet provides the base for the production of modern, three-dimensional nanostructures from this special material and, thus, enables a large number of future (spin transport) experiments.