Cryogenic atomic force microscopy system integrated in cryogen-free dilution refrigerator for single-electron sensitive electric force microscopy/spectroscopy*

 We present a cryogenic atomic force microscopy (AFM) system which is integrated in a cryogen-free dilution refrigerator with magnetic field up to 9 T. A large internal volume of the cryostat allows the AFM unit to be installed on an efficient internal vibration isolation system, enabling good mechanical stability. Combined with the rigid design of coarse positioners, the influence from the pulse tube cooler is minimized. The AFM is equipped with a fiber-optic interferometer which is used for both detecting the cantilever deflection and exciting the cantilever oscillation [1]. The capability of optically exciting cantilever oscillation enables tunable cantilever quality factor and the clean cantilever resonance, which is crucial for single-electron sensitive electric force microscopy/spectroscopy [2,3]. We will present the details of the system and its performance.  

[1] Y. Miyahara et al., “Optical excitation of atomic force microscopy cantilever for accurate spectroscopic measurements”, EPJ tech. Instrum. 7:2 (2020). 

[2] Y. Miyahara, A. Roy-Gobeil, and P. Grutter, "Quantum state readout of individual quantum dots by electrostatic force detection", Nanotechnology 28, 1 (2017).

[3] A. Labuda et al., "Decoupling conservative and dissipative forces in frequency modulation atomic force microscopy", Phys. Rev. B84, 125433 (2011).