Battisti Irene, Verdoes Gijsbert, van Oosten Kees, Bastiaans Koen M, Allan Milan P
Leiden Institute of Physics, Leiden University, 2333 CA Leiden, The Netherlands.
Rev Sci Instrum. 2018 Dec;89(12):123705. doi: 10.1063/1.5064442.
Spectroscopic-imaging scanning tunneling microscopy is a powerful technique to study quantum materials, with the ability to provide information about the local electronic structure with subatomic resolution. However, as most spectroscopic measurements are conducted without feedback to the tip, it is extremely sensitive to vibrations coming from the environment. This requires the use of laboratories with low-vibration facilities combined with a very rigid microscope construction. In this article, we report on the design and fabrication of an ultra-stable scanning tunneling microscope (STM) for spectroscopic-imaging measurements that operates in ultra-high vacuum and at low temperatures (4 K). We start from existing designs with sapphire as the main material and improve the stiffness further by performing finite element analysis calculations for the main components of the microscope to guide design choices on the geometry of the parts. With this strategy, we construct a STM head with measured lowest resonant frequencies above = 13 kHz for the coarse approach mechanism, a value three times higher than what has been previously reported and in good agreement with the calculations. This allows us to achieve an average vibration level of ∼6 fm , without a dedicated low-vibration lab. We demonstrate the microscope's performance with topographic and spectroscopic measurements on the correlated metal SrRhO, showing the quasiparticle interference pattern in real and reciprocal space with high signal-to-noise ratio.
光谱成像扫描隧道显微镜是研究量子材料的一种强大技术，能够以亚原子分辨率提供有关局部电子结构的信息。然而，由于大多数光谱测量是在没有反馈到探针的情况下进行的，因此它对来自环境的振动极其敏感。这就需要使用配备低振动设施的实验室，并结合非常坚固的显微镜结构。在本文中，我们报告了一种用于光谱成像测量的超稳定扫描隧道显微镜（STM）的设计与制造，该显微镜在超高真空和低温（4K）下运行。我们从以蓝宝石为主要材料的现有设计入手，通过对显微镜的主要部件进行有限元分析计算来进一步提高其刚度，以指导部件几何形状的设计选择。采用这种策略，我们构建了一个STM探头，其粗进机制的测量最低共振频率高于13kHz，该值比之前报道的高出三倍，且与计算结果吻合良好。这使我们能够在没有专用低振动实验室的情况下，实现约6fm的平均振动水平。我们通过对关联金属SrRhO进行形貌和光谱测量来展示该显微镜的性能，在实空间和倒易空间中以高信噪比显示了准粒子干涉图案。
