Namkyung Lee

Seoul National University

Department of Physics and Astronomy

We report the development of a variable-temperature Kelvin probe force microscopy(KPFM)

system capable of stable and highly sensitive operation over a wide temperature range based on a

GM-cooler-based cryogen-free cryostat. The system incorporates a custom-designed phase-locked

loop and automatic gain control, along with passive vibration isolation, enabling precise

measurements of local chemical potential even under cryogenic conditions. We demonstrate the

performance of this setup by measuring hBN encapsulated monolayer graphene (MLG), revealing

spatially resolved electronic inhomogeneities and charge puddles. Our measurements clearly

capture temperature-dependent variations in the chemical potential near the charge neutrality point

(CNP), consistent with the linear band dispersion of MLG and interaction-driven renormalization of

Fermi velocity. This work highlights the robust sensitivity and stability of our system, making it a
versatile local probe of quantum phases in van der Waals heterostructures.