Scanning SQUID-on-tip microscope in a top-loading cryogen-free dilution refrigerator

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Scanning superconducting quantum interference device (SQUID) on tip technology offers nanoscale imaging capabilities for quantum materials.
• Existing setups may face limitations in vibration control and thermal imaging integration.

Purpose of the Study:

• To design and demonstrate a cryogen-free scanning SQUID-on-tip microscope for advanced nanoscale characterization.
• To enable simultaneous magnetic, thermal, and transport property measurements of quantum materials.

Main Methods:

• Integration of a SQUID-on-tip within a top-loading probe of a cryogen-free dilution refrigerator.
• Implementation of a custom vacuum-tight cell with vibration isolation and in situ helium exchange gas control.
• Utilizing a nanoscale heater for thermal gradient generation and vibration characterization.

Main Results:

• Successful magnetic imaging of MnBi2Te4 (magnetic topological insulator).
• Demonstrated magnetization and current distribution imaging in SrRuO3 (ferromagnetic oxide).
• Achieved thermal imaging of dissipation in graphene, with characterized tip-sample vibrations up to 27 nm/Hz1/2.

Conclusions:

• The developed scanning SQUID-on-tip microscope is a versatile platform for nanoscale property mapping of quantum materials.
• The system effectively suppresses vibrations and allows for precise thermal and magnetic imaging.
• This technology advances the study of complex quantum phenomena at the nanoscale.