Wu Dan, Wang Jihao, Dong Shuai, Li Zihao, Liang Rong, Wang Aile, Zhang Min, Zhang Jing, Feng Qiyuan, Meng Wenjie, Hou Yubin, Lu Qingyou
Anhui Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui 230031, China.
University of Science and Technology of China, Hefei, Anhui 230026, China.
Rev Sci Instrum. 2025 Aug 1;96(8). doi: 10.1063/5.0266265.
Manipulating the direction of the magnetic field can induce various intriguing physical phenomena, such as the regulation of nematic phase and disappearance of the charge density wave. Conventional superconducting magnet-based scanning tunneling microscopes (STMs) operate with a perpendicular magnetic field direction to the sample surface, limiting their ability to investigate anisotropy of materials. Some STMs are integrated into vector magnets to achieve in-plane magnetic field conditions; however, these setups typically offer a maximum lateral magnetic field strength of less than 5 T, which is far below the critical magnetic field required for many materials. To explore the anisotropy of materials under in-plane magnetic fields exceeding 20 T, a new STM with small lateral tip-sample junction, which is capable of working in huge vibrational water-cooled magnets, is required. This paper presents an innovative design of such a small lateral size featured STM that is capable of operating under 35 T in-plane magnetic field conditions. The proposed STM utilizes an improved spider drive to drive the tip move in oblique upward direction, with the component of tip motion on the lateral direction being one-fifth of the vertical direction. With the novel design, the lateral size of the STM head is minimized to as small as 15 mm. The high rigidity of an independent scanner is proved by the high eigenfrequencies obtained through finite element analysis. The excellent imaging ability of our new STM are demonstrated by the high-quality atomic images of graphite and NbSe2 acquired under in-plane magnetic fields ranging from 0 to 35 T, illustrating the new STM's high immunity to the magnetic field conditions. As far as known, this is the first STM capable of atomic imaging at magnetic field up to 35 T and capable of working at both 300 and 1.7 K low temperature; this is also the first water-cooled magnet STM capable of atomic imaging under 35 T magnetic field and huge vibrational conditions. Using this STM, we expect to investigate novel physical phenomena occurring under high in-plane magnetic fields.
操纵磁场方向可以引发各种有趣的物理现象，例如向列相的调控以及电荷密度波的消失。传统的基于超导磁体的扫描隧道显微镜（STM）在与样品表面垂直的磁场方向下工作，这限制了它们研究材料各向异性的能力。一些STM被集成到矢量磁体中以实现面内磁场条件；然而，这些装置通常提供的最大横向磁场强度小于5 T，这远低于许多材料所需的临界磁场。为了探索在超过20 T的面内磁场下材料的各向异性，需要一种具有小横向针尖 - 样品结、能够在巨大振动的水冷磁体中工作的新型STM。本文提出了一种这种具有小横向尺寸特点的STM的创新设计，它能够在35 T面内磁场条件下运行。所提出的STM利用改进的蜘蛛驱动来驱动针尖沿斜向上方向移动，针尖在横向方向上的运动分量是垂直方向的五分之一。通过这种新颖的设计，STM头部的横向尺寸最小化至仅15 mm。通过有限元分析获得的高本征频率证明了独立扫描器的高刚性。我们新型STM的出色成像能力通过在0至35 T面内磁场下获取的高质量石墨和NbSe2原子图像得到了证明，这说明了新型STM对磁场条件具有高抗性。据我们所知，这是第一台能够在高达35 T的磁场下进行原子成像并且能够在300 K和1.7 K低温下工作的STM；这也是第一台能够在35 T磁场和巨大振动条件下进行原子成像的水冷磁体STM。使用这台STM，我们期望研究在高面内磁场下发生的新型物理现象。
