A modular ultra-high vacuum millikelvin scanning tunneling microscope

Area of Science:

• Materials Science
• Condensed Matter Physics
• Cryogenics

Background:

• Scanning tunneling microscopy (STM) requires ultra-high vacuum (UHV) conditions.
• Dilution refrigerators operate at extremely low temperatures but are not typically UHV compatible.
• Integrating UHV STM with dilution refrigerators presents engineering challenges.

Purpose of the Study:

• To design and construct a modular UHV-STM for operation at dilution refrigerator temperatures.
• To enable high-resolution imaging and measurements at millikelvin temperatures.
• To facilitate easy maintenance and upgrades of the STM system.

Main Methods:

• A modular design partitioning the UHV STM from the dilution refrigerator.
• Utilizing separable and interchangeable components for the STM system.
• Implementing a fully bakeable UHV chamber for the STM head.

Main Results:

• Successful integration of UHV-STM with a dilution refrigerator.
• Demonstrated high level of modularity allowing for swift microscope head removal.
• Achieved an electron temperature of 184 mK on a superconducting Al(100) crystal without cryogenic filters.

Conclusions:

• The modular design effectively separates UHV and cryogenic systems, simplifying construction and maintenance.
• The system enables advanced low-temperature STM experiments.
• The achieved low electron temperature highlights the system's performance capabilities.