A Milli-Kelvin Atomic Force Microscope Made of Glass

TL;DR

This paper introduces a low-cost, large-range atomic force microscope operating below 100 mK, made entirely of fused silica glass to minimize vibrations and heat dissipation in cryogen-free dilution refrigerators.

Contribution

It presents a novel design of a milli-Kelvin AFM with custom-made fused silica components, achieving high stiffness, thermal insulation, and large scan range at ultra-low temperatures.

Findings

Operates below 100 mK with a 25 μm × 25 μm scan range

Uses fused silica for all critical parts to enhance rigidity and thermal insulation

Balances heat dissipation and stiffness for optimal performance at mK temperatures

Abstract

Milli-Kelvin atomic force microscopy (mK-AFM) presents an ongoing experimental challenge due to the intense vibrations in a cryogen-free dilution refrigerator and the low cooling power available at mK temperatures. A viable approach is to make the system exceptionally rigid and thermally insulating to decouple external vibrations and isolate heat dissipation from the piezo elements. Here, we present a low-cost and large scan-range mK-AFM that operates below 100 mK. All the essential parts of our mK-AFM, including the scanners, tip assembly, and microscope body, are custom-made of fused silica glass by taking advantage of its high specific modulus, extremely low thermal expansion coefficient, and excellent thermal insulation properties. We carefully balance the scan range (25 ${\mu}$m $\times$ 25 ${\mu}$m), heat dissipation, and stiffness of the system to reach optimal performance at mK temperatures.