Applied Physics Department, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel.
Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel.
Adv Mater. 2019 Oct;31(40):e1904206. doi: 10.1002/adma.201904206. Epub 2019 Aug 18.
Local magnetic imaging at nanoscale resolution is desirable for basic studies of magnetic materials and for magnetic logic and memories. However, such local imaging is hard to achieve by means of standard magnetic force microscopy. Other techniques require low temperatures, high vacuum, or strict limitations on the sample conditions. A simple and robust method is presented for locally resolved magnetic imaging based on short-range spin-exchange interactions that can be scaled down to atomic resolution. The presented method requires a conventional AFM tip functionalized with a chiral molecule. In proximity to the measured magnetic sample, charge redistribution in the chiral molecule leads to a transient spin state, caused by the chiral-induced spin-selectivity effect, followed by the exchange interaction with the imaged sample. While magnetic force microscopy imaging strongly depends on a large working distance, an accurate image is achieved using the molecular tip in proximity to the sample. The chiral molecules' spin-exchange interaction is found to be 150 meV. Using the tip with the adsorbed chiral molecules, two oppositely magnetized samples are characterized, and a magnetic imaging is performed. This method is simple to perform at room temperature and does not require high-vacuum conditions.
在纳米尺度分辨率下进行局部磁成像对于磁性材料的基础研究以及磁性逻辑和存储器非常重要。然而，通过标准的磁力显微镜很难实现这种局部成像。其他技术需要低温、高真空或对样品条件的严格限制。本文提出了一种基于短程自旋交换相互作用的简单而稳健的局部磁成像方法，该方法可以扩展到原子分辨率。所提出的方法需要一个功能化有手性分子的常规原子力显微镜探针。在手性分子接近被测磁性样品时，手性分子中的电荷重新分布会导致瞬态自旋状态，这是由手性诱导的自旋选择性效应引起的，随后与被测样品发生交换相互作用。虽然磁力显微镜成像强烈依赖于大的工作距离，但通过分子探针在接近样品的位置可以获得准确的图像。研究发现，手性分子的自旋交换相互作用为 150 毫电子伏特。使用吸附在手性分子上的探针对两个具有相反磁化的样品进行了表征，并进行了磁成像。该方法在室温下操作简单，不需要高真空条件。
