Kim Geunyong, Yun Jinyoung, Lee Yeonkyu, Kim Jeehoon
Department of Physics, Pohang University of Science and Technology, Pohang 37673, South Korea.
Rev Sci Instrum. 2022 Jun 1;93(6):063701. doi: 10.1063/5.0092264.
Owing to the high resolution of magnetic force microscopes (MFMs) operating at low temperatures and high-applied magnetic fields, they can be employed to study various phenomena observed in topological magnetic materials and superconductors. In this study, we constructed a low-temperature MFM equipped with a 2-2-9-T vector magnet and a three-axis fiber-optic alignment system. The three-axis alignment device enables in situ calibration of the scanner at low temperatures as well as optimizes the intensity and sensitivity of the interferometer signal. A massive homebuilt vibration isolation table lowers the resonance frequency of the system and minimizes mechanical noise. Consequently, the minimum detectable force gradient of our proposed model is close to the thermodynamic limit of the cantilever. To demonstrate the low-temperature capability of the MFM, we obtained magnetic domain images of the van der Waals ferromagnet FeGeTe and the Abrikosov superconducting vortices of an Nb film. Furthermore, we performed field angle-dependent MFM experiments in a van der Waals magnetic insulator CrGeTe to verify its vector-field functionality and observed a transition in the domains from the stripe to the bubble phase with respect to the magnetic field angle. The vector-field capability of our MFM can be useful for investigating various anisotropic magnetic phenomena in topological magnetic and superconducting materials.
由于磁力显微镜（MFM）在低温和高外加磁场下具有高分辨率，因此可用于研究拓扑磁性材料和超导体中观察到的各种现象。在本研究中，我们构建了一台配备2 - 2 - 9 T矢量磁体和三轴光纤对准系统的低温MFM。该三轴对准装置能够在低温下对扫描器进行原位校准，并优化干涉仪信号的强度和灵敏度。一个大型自制隔振台降低了系统的共振频率，并将机械噪声降至最低。因此，我们所提出模型的最小可检测力梯度接近悬臂梁的热力学极限。为了展示MFM的低温性能，我们获得了范德华铁磁体FeGeTe的磁畴图像和Nb薄膜的阿布里科索夫超导涡旋图像。此外，我们在范德华磁绝缘体CrGeTe中进行了与场角相关的MFM实验，以验证其矢量场功能，并观察到磁畴相对于磁场角从条纹相到泡状相的转变。我们的MFM的矢量场能力可用于研究拓扑磁性和超导材料中的各种各向异性磁现象。
