Çelik Ümit, Karcı Özgür, Uysallı Yiğit, Özer H Özgür, Oral Ahmet
NanoMagnetics Instruments Ltd., METU Technopolis, 06800 Ankara, Turkey.
Department of Physics, Middle East Technical University, 06800 Ankara, Turkey.
Rev Sci Instrum. 2017 Jan;88(1):013705. doi: 10.1063/1.4973819.
We describe a novel radiation pressure based cantilever excitation method for imaging in dynamic mode atomic force microscopy (AFM) for the first time. Piezo-excitation is the most common method for cantilever excitation, however it may cause spurious resonance peaks. Therefore, the direct excitation of the cantilever plays a crucial role in AFM imaging. A fiber optic interferometer with a 1310 nm laser was used both for the excitation of the cantilever at the resonance and the deflection measurement of the cantilever in a commercial low temperature atomic force microscope/magnetic force microscope (AFM/MFM) from NanoMagnetics Instruments. The laser power was modulated at the cantilever's resonance frequency by a digital Phase Locked Loop (PLL). The laser beam is typically modulated by ∼500 μW, and ∼141.8 nm oscillation amplitude is obtained in moderate vacuum levels between 4 and 300 K. We have demonstrated the performance of the radiation pressure excitation in AFM/MFM by imaging atomic steps in graphite, magnetic domains in CoPt multilayers between 4 and 300 K and Abrikosov vortex lattice in BSCCO(2212) single crystal at 4 K for the first time.
我们首次描述了一种基于辐射压力的新型悬臂梁激发方法，用于动态模式原子力显微镜（AFM）成像。压电激发是悬臂梁激发最常用的方法，然而它可能会导致虚假共振峰。因此，悬臂梁的直接激发在AFM成像中起着至关重要的作用。在NanoMagnetics Instruments公司的商用低温原子力显微镜/磁力显微镜（AFM/MFM）中，使用了一台波长为1310 nm的光纤干涉仪，既用于在共振时激发悬臂梁，也用于测量悬臂梁的偏转。通过数字锁相环（PLL）在悬臂梁的共振频率上调制激光功率。激光束通常被调制约500 μW，在4至300 K的中等真空水平下获得约141.8 nm的振荡幅度。我们首次通过对石墨中的原子台阶、4至300 K之间的CoPt多层膜中的磁畴以及4 K时BSCCO(2212)单晶中的阿布里科索夫涡旋晶格进行成像，展示了AFM/MFM中辐射压力激发的性能。
