Zhang Min, Wang Jihao, Meng Wenjie, Zhang Jing, Feng Qiyuan, Wang Ze, Lu Yalin, Hou Yubin, Lu Qingyou
University of Science and Technology of China, Hefei, Anhui 230026, China.
Anhui Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China.
Rev Sci Instrum. 2024 Mar 1;95(3). doi: 10.1063/5.0191662.
Low-temperature scanning tunneling microscopy and spectroscopy (STM/S) help to better understand the fundamental physics of condensed matter. We present an ultracompact STM within a Φ 10 piezo tube in a 20 T superconducting magnet. The carefully cut piezo tube contains the STM's coarse-positioning assembly. Loading an STM tip-sample mechanical loop into the piezo tube with special cut openings enables an ultracompact pencil-size dimension down to Φ 10 mm, in which fine-machined nonmagnetic parts are assembled to enable slide-stick motion and xyz-scanning procedures. The small size leads to a higher resonant frequency, a typical feature of a rigid STM instrument, increasing its vibration immunity. Scanning by moving the sample while keeping the tip stationary improves the stability of the tip-sample junction compared to moving the tip. Taking advantage of its high-field compatibility and rigid design, our STM captures the atomically resolved topography of highly oriented pyrolytic graphite (HOPG) at 1.5 K and in magnetic fields up to 17 T. The topography of graphene lattice and graphite is simultaneously recorded on an atomic terrace of HOPG, unveiling a modified local charge density at a surface defect. The superconducting energy gaps of layered type-II superconductors NbSe2 and PdBi2 are well resolved through dI/dV tunneling spectra at sub-2 K. Our unique STM is highly suitable for potential STM/S applications in world-class high-field facilities where the strong magnetic field can exceed 30 T.
低温扫描隧道显微镜和光谱学（STM/S）有助于更好地理解凝聚态物质的基础物理学。我们展示了一种在20 T超导磁体中置于直径10毫米压电管内的超紧凑型STM。精心切割的压电管包含STM的粗定位组件。通过特殊切割开口将STM针尖 - 样品机械回路装入压电管，可实现低至直径10毫米的超紧凑型铅笔尺寸，其中组装了精细加工的非磁性部件以实现滑动 - 粘贴运动和xyz扫描程序。小尺寸导致更高的共振频率，这是刚性STM仪器的典型特征，增强了其抗振性。与移动针尖相比，通过在保持针尖固定的同时移动样品进行扫描可提高针尖 - 样品结的稳定性。利用其高场兼容性和刚性设计，我们的STM在1.5 K和高达17 T的磁场中捕获了高度取向热解石墨（HOPG）的原子分辨形貌。在HOPG的原子平台上同时记录了石墨烯晶格和石墨的形貌，揭示了表面缺陷处的局部电荷密度变化。通过在低于2 K的温度下的dI/dV隧道谱很好地分辨了层状II型超导体NbSe2和PdBi2的超导能隙。我们独特的STM非常适合在世界级高场设施中潜在的STM/S应用，在这些设施中强磁场可超过30 T。
