USM1800 Cryogen-Free Low Temperature UHV Scanning Probe Microscope

Realization of STM & AFM with atomic resolution below 6 K by mechanical refrigeration
Continuous cooling for long periods of time without the use of scarce liquid helium
STM-TERS is now available【New】

The closed-cycle USM1800 LT UHV SPM is now part of the UNISOKU SPM product family! The USM1800 provides sample temperatures below 6 K, and the cryogen-free cooling system achieves ultimate SPM performance at low temperature while allowing interruption-free measurement conditions.

Features

• Sample temperature below 6 K (when optical window shielding is closed)
• State-of-the-art SPM platform with atomic resolution imaging (qPlus® AFM is available as an option)
• Optical access and in-situ deposition capabilities (inertial-driven lens stages on the SPM platform are available as an option)
• The sample holder is available in either the conventional bayonet type or the flag type.

Applications

• Replacement of a liquid-helium-based low-temperature SPM system
• Observation of quasi-particle interference patterns by tunneling spectral mapping
• Observation of surface adsorption structure using in-situ deposition capabilities
• Studies of photo-induced phenomenon in combination with simultaneous SPM measurements



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Schematic view of the USM1800 system



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Cooling performance

Cooling time: <6 K in 24 hours




Temperature stability @ 5.2 K




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Long-term stability of STM

Long-term STM images of Si(111) surface @T = 4.8 K




 

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Tunneling current noise spectrum




Superconducting gap of Pb




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Nc-AFM NaCl atomic image at 6 K




Sample: NaCl (100)
AFM sensor: qPlus®
Amplitude: 200 pm
Frequency shift: -13 Hz


STM Au(111) atomic image at 5.6 K




Sample: Au(111)
Scan size: 7 nm x 7 nm
Bias voltage: +5 mV
Tunnel current: 1 nA


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TERS at 8 K【New】





 
 

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Specifications

SPM structure	Tip scanning type Coarse positioning for X,Y (ø 1 mm) and Z (5 mm)
Scan range	1 um × 1 um at 6 K
Sample holder	Bayonet style holder, Flag style holder (DC heating, EB heating, cleaving)
Temperature	<6 K 1.5 year in each for Maintenance (Pulse tube refrigerator)
Options	Internal optical lens stages with 3D coarse positioning (NA ～ 0.25) Tuning Fork NC-AFM
Chamber structure	Includes SPM observation chamber, preparation chamber, and loadlock chamber. In-situ UHV sample/probe holder transfers

Laboratory Requirements

Recommended laboratory area	Floor space: 4 m × 4 m, Ceiling height: > 2.8 m
Floor vibration level	< 1 μm/s (rms) below 5 Hz < 3 μm/s between 5-10 Hz < 5 μm/s above 10 Hz
Preparation of equipment	•Cooling water •Three-phase electric power

Publications

"Development of a near-5-Kelvin, cryogen-free, pulse-tube refrigerator-based scanning probe microscope"
   J. Kasai et al., Rev. Sci. Instrum. 93, 043711 (2022).

"Layer thickness and substrate effects on superconductivity in epitaxial FeSe films on BLG/SiC(0001)"
   Y. Wang et al., Phys. Rev. Research 7, 023288 (2025).

"Direct experimental evidence of transient Au^δ+ oxide in Au electrooxidation"
   J. Redondo et al., J. Am. Chem. Soc. 148, 12587 (2026).

"Moiré-induced symmetry breaking of charge order in van der Waals heterostructures"
   S. Sajan et al., arXiv:2603.05759

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PDF SPM System Specs.