Investigation of magnetization dynamics of vortices probed by high frequency scanning tunneling microscopy

在这个项目中，我们将研究纳米结构的磁化动力学，特别是磁涡流。这些测量是基于最近开发的高频扫描隧道显微镜，它的时间分辨率可达120ps。到目前为止，这种方法是唯一一种结合了空间分辨率到原子尺度、高时间分辨率和自旋极化尖端对磁系统进行局部激发的可能性的方法。这将使我们能够研究原子尺度下的磁化动力学。我们将探索这一新的可能性来研究涡旋结构对离涡核或缺陷一定距离的局部激发的响应。通过带状线的全局激发，我们的目标是以原子分辨率对涡旋动力学进行时间成像，以精确地定位缺陷和外场对涡旋动力学的影响。我们将使用在W(110)上制备的Fe纳米岛，其涡旋高度约为7 nm，横向长度尺度为100 nm。制备过程采用分子束外延(MBE)原位进行。磁性缺陷是由于在低温下沉积的外来原子的原子操纵造成的。对于自旋动力学的时间分辨成像，我们将直接在W(110)带线上制备磁性纳米结构。

Within this project, we will investigate the magnetization dynamics of nanostructures, in particular, magnetic vortices. The measurements are based on a recently developed high-frequency scanning tunneling microscope, which exhibits time resolution down to 120 ps. This method is, so far, the only one which combines spatial resolution down to the atomic scale, high time resolution and the possibility of local excitation of the magnetic system by spin-polarized tips. This will allow to study magnetization dynamics down to the atomic scale. We will explore this novel possibility to study the response of the vortex structure to local excitations in defined distance to the vortex core or at defects. Using global excitation via striplines, we aim at a temporal imaging of the vortex dynamics with atomic resolution in order to pinpoint the influence of defects and external fields on the dynamics.We will use Fe nanoislands prepared on W(110), which exhibit a vortex at a height of about 7nm and lateral length scales of 100 nm. The preparation is performed in-situ using molecular beam epitaxy (MBE). Magnetic defects are created by atomic manipulation of foreign atoms deposited at low temperature. For the time-resolved imaging of the spin dynamics, we will prepare the magnetic nanostructures directly on a W(110) stripline.