A compact ultrahigh vacuum scanning tunneling microscope with dilution refrigeration

Area of Science:

• Experimental Physics
• Low-Temperature Physics
• Surface Science

Background:

• Scanning tunneling microscopy (STM) requires precise control of temperature and environmental conditions.
• Achieving millikelvin temperatures and high magnetic fields simultaneously presents significant engineering challenges.

Purpose of the Study:

• To design and construct a novel STM setup capable of operation at millikelvin temperatures within an ultrahigh vacuum environment.
• To enable high-resolution surface studies under extreme conditions, including high magnetic fields.

Main Methods:

• A compact cryostat with an integrated dilution refrigerator was developed, achieving a base temperature of 25 mK.
• Mechanical decoupling and low-pass filtering were employed to minimize vibrations and electronic noise.
• The STM is designed for easy sample/tip exchange and precise positioning within a superconducting magnetic coil.

Main Results:

• The setup operates at a base temperature of 25 mK and magnetic fields up to 7.5 T.
• Mechanical vibrations were reduced to below 1 pm/math.
• Electronic temperature was lowered to below 100 mK, confirmed by superconducting aluminum quasiparticle peaks.

Conclusions:

• A versatile and compact STM system for millikelvin operation in ultrahigh vacuum and high magnetic fields has been successfully realized.
• The design minimizes noise and facilitates user-friendly operation, making it suitable for advanced materials characterization.