A Joule-Thomson low-temperature scanning tunneling microscope with vector magnet and rotatable scanning head

Area of Science:

• Condensed Matter Physics
• Low-Dimensional Materials
• Surface Science

Background:

• Scanning tunneling microscopy (STM) is crucial for atomic-level surface analysis.
• Precise control over magnetic fields is essential for studying quantum phenomena in materials.
• Existing STM systems often have limitations in magnetic field manipulation and temperature control.

Purpose of the Study:

• To develop an advanced STM system for frontier investigations in low-dimensional condensed matter physics.
• To enable three-dimensional (3D) magnetic field manipulation at cryogenic temperatures.
• To achieve ultra-low temperatures with efficient cryogen consumption.

Main Methods:

• Integration of a Joule-Thomson (JT) cooled STM with a two-axis vector magnet.
• Utilizing a piezoelectrically rotatable STM head and a commercial superconducting magnet (8 T out-of-plane, 2 T in-plane).
• Employing a dual-dewar architecture for efficient cooling to 1.2 K and ultrahigh vacuum (UHV) conditions with molecular beam epitaxy (MBE).

Main Results:

• Demonstrated atomic-resolution imaging stability and high-resolution tunneling spectroscopy.
• Achieved a base temperature of 1.2 K with minimal cryogen usage.
• Successfully integrated 3D magnetic field control with a bottom-loading, optically accessible STM design.

Conclusions:

• The developed JT-cooled STM system provides unprecedented capabilities for exploring low-dimensional materials.
• The system's design facilitates in-situ sample manipulation and characterization under combined magnetic fields and UHV/MBE conditions.
• Future upgrades, including dilution refrigeration, are compatible, extending the system's research potential.