Mapping spin accumulation in lateral spin momentum transfer devices using Brillouin light scattering microscopy

自旋动量转移效应是当代磁学研究的热点问题。它们利用了这样一个事实，即除了电荷外，电子还带有一个磁矩。因此，自旋极化电子的电流可以传递角动量，例如在分层结构中的两个磁层之间或在横向设备中的两个物体之间。可以预见许多新的应用，从具有超小特征尺寸的新的磁随机存取存储器到新的微波发生器[参见例如Der07，Wat06，Zut07]。到目前为止使用的大多数研究的几何形状都是垂直的器件几何形状，即，使用具有自旋电流垂直方向的图案化技术从多层制造而成。最近的发展包括横向自旋转移装置，在这种装置中，自旋极化的电子在位于衬底上横向相邻的纳米制造的磁性物体之间转移角动量。日本合作伙伴大谷洋一教授是这一领域的世界领先科学家之一[Kim07a-b，Kim06a-b，Kim05a-b，Ham05a-c]。

Spin momentum transfer effects are a hot topic in contemporary magnetism. They take advantage from the fact, that the electron carries a magnetic moment in addition to the charge. Thus, a current of spin polarized electrons can transfer angular momentum, for instance between two magnetic layers in a layered structure or between two objects in a lateral device. Many new applications can be envisioned, ranging from new magnetic random access memory with ultra-small feature sizes to new microwave generators [see e.g. Der07, Wat06, Zut07]. Most investigated geometries used so far have been vertical device geometries, i.e. fabricated from a multilayer using patterning techniques with vertical direction of the spin current flow. The very recent developments encompass lateral spin transfer devices, where spin polarized electrons transfer angular momentum between nano-fabricated magnetic objects positioned laterally next to each other on a substrate. The Japanese partner, Prof. Yoshichika Otani, is one of the world-leading scientists in this field [Kim07a-b,Kim06a-b,Kim05a-b,Ham05a-c].