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arXiv · 2204.01195

Development of a near-5-Kelvin, cryogen-free, pulse-tube refrigerator-based scanning probe microscope

Jun Kasai·Tomoki Koyama·Munenori Yokota·Katsuya Iwaya
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Abstract

We report the design and performance of a cryogen-free, pulse-tube refrigerator (PTR)-based scanning probe microscopy (SPM) system capable of operating at the base temperature of near 5K. We achieve this by combining a home-made interface design between the PTR cold head and the SPM head, with an automatic gas-handling system. The interface design isolates the PTR vibrations by a combination of polytetrafluoroethylene and stainless-steel bellows, and by placing the SPM head on a passive vibration isolation table via two cold stages that are connected to thermal radiation shields using copper heat links. The gas-handling system regulates the helium heat-exchange gas pressures, facilitating both the cool down to and the maintenance of the base temperature. We discuss the effects of each component using measured vibration, current-noise, temperature, and pressure data. We demonstrate that our SPM system performance is comparable to known liquid-helium-based systems with the measurements of the superconducting gap spectrum of Pb, atomic-resolution scanning tunneling microscopy image and quasiparticle interference pattern of Au(111) surface, and non-contact atomic force microscopy image of NaCl(100) surface. Without the need for cryogen refills, the current SPM system enables uninterrupted low-temperature measurements.

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Jun Kasai, Tomoki Koyama, Munenori Yokota, Katsuya Iwaya. 2022-04-04. Development of a near-5-Kelvin, cryogen-free, pulse-tube refrigerator-based scanning probe microscope. https://doi.org/10.1063/5.0084888

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