Pendulum mode atomic force microscope in cryogen-free dilution refrigerator for single-electron sensitive electric force microscopy/spectroscopy

We present a pendulum-mode atomic force microscopy (AFM) system integrated into a cryogen-free dilution refrigerator. In pendulum-mode operation, the AFM employs a cantilever with a very low spring constant, making it well suited for detecting weak electric forces arising from single-electron tunneling. The AFM incorporates a fiber-optic interferometer used for both measuring the cantilever deflection and optically exciting its oscillation. Optical excitation of the cantilever enables tuning of its quality factor [1] and yields a clean resonance response [2,3], both of which are crucial for single-electron-sensitive electric force microscopy and spectroscopy [4] . The design and performance of the system will be presented.

[1] N. Austin-Bingamon et al., "Control of quality factor of atomic force microscopy cantilever by cavity optomechanical effect", Jpn. J. Appl. Phys. 63, 04SP84 (2024).

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

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

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